Scholars@Duke
Michael Rubinstein

Michael Rubinstein

Aleksandar S. Vesic Distinguished Professor
Thomas Lord Department of Mechanical Engineering and Materials Science
michael.rubinstein@duke.edu
Box 90300, Durham, NC 27708
3377 CIEMAS Building, Box 90300, Durham, NC 27708

Selected Publications

Rapid self-strengthening in double-network hydrogels triggered by bond scission.

Journal Article Nature materials · February 2025 The scission of chemical bonds in materials can lead to catastrophic failure, with weak bonds typically undermining the materials' strength. Here we demonstrate how weak bonds can be leveraged to achieve self-strengthening in polymer network materials. The ... Full text Cite

Physiology and pathophysiology of human airway mucus.

Journal Article Physiological reviews · October 2022 The mucus clearance system is the dominant mechanical host defense system of the human lung. Mucus is cleared from the lung by cilia and airflow, including both two-phase gas-liquid pumping and cough-dependent mechanisms, and mucus transport rates are heav ... Full text Cite

Fibrous hydrogels under biaxial confinement.

Journal Article Nature communications · June 2022 Confinement of fibrous hydrogels in narrow capillaries is of great importance in biological and biomedical systems. Stretching and uniaxial compression of fibrous hydrogels have been extensively studied; however, their response to biaxial confinement in ca ... Full text Cite

Scaling Theory of Swelling and Deswelling of Polymer Networks

Journal Article Macromolecules · May 10, 2022 We have developed a scaling theory of the elasticity of swollen and deswollen polymer networks. The elasticity of unentangled networks is primarily due to cross-links, and the elasticity of entangled networks is due to trapped entanglements. In preparation ... Full text Cite

Mucus concentration-dependent biophysical abnormalities unify submucosal gland and superficial airway dysfunction in cystic fibrosis.

Journal Article Science advances · April 2022 Cystic fibrosis (CF) is characterized by abnormal transepithelial ion transport. However, a description of CF lung disease pathophysiology unifying superficial epithelial and submucosal gland (SMG) dysfunctions has remained elusive. We hypothesized that bi ... Full text Cite

Understanding Gas Transport in Polymer-Grafted Nanoparticle Assemblies.

Journal Article Macromolecules · April 2022 We rationalize the unusual gas transport behavior of polymer-grafted nanoparticle (GNP) membranes. While gas permeabilities depend specifically on the chemistry of the polymers considered, we focus here on permeabilities relative to the corresponding pure ... Full text Cite

Where in the world are condensed counterions?

Journal Article Soft matter · February 2022 A scaling model of the concentration profiles of both condensed and free counterions is presented for solutions of spherical and cylindrical charged nanoparticles of different charge valences, nanoparticle sizes, and salt concentrations. The distribution o ... Full text Cite

Overlap Concentration in Salt-Free Polyelectrolyte Solutions

Journal Article Macromolecules · November 9, 2021 For strongly charged polyelectrolytes in salt-free solutions, we use molecular dynamics simulations of a coarse-grained bead-spring model to calculate overlap concentrations c∗ and chain structure for polymers containing N = 10 to 1600 monomers. Over much ... Full text Cite

Universal Polymeric-to-Colloidal Transition in Melts of Hairy Nanoparticles.

Journal Article ACS nano · October 2021 Two different classes of hairy self-suspended nanoparticles in the melt state, polymer-grafted nanoparticles (GNPs) and star polymers, are shown to display universal dynamic behavior across a broad range of parameter space. Linear viscoelastic measurements ... Full text Cite

Toughening hydrogels through force-triggered chemical reactions that lengthen polymer strands.

Journal Article Science (New York, N.Y.) · October 2021 The utility and lifetime of materials made from polymer networks, including hydrogels, depend on their capacity to stretch and resist tearing. In gels and elastomers, those mechanical properties are often limited by the covalent chemical structure of the p ... Full text Cite

Diffusion of Thin Nanorods in Polymer Melts.

Journal Article Macromolecules · August 2021 The diffusion of monomerically thin nanorods in polymer melts is studied by molecular dynamics simulations. We focus on the systems where chains are long enough to screen the hydrodynamic interactions such that the diffusion coefficient D∥ Full text Cite

Gas Transport in Interacting Planar Brushes.

Journal Article ACS polymers Au · August 2021 Recent experiments on melts of spherical nanoparticles (NPs) densely grafted with polymer chains show enhanced gas transport relative to the neat polymer (without NPs). As a means of understanding this unexpected behavior, we consider here the simpler case ... Full text Cite

Nonlinear rheometry of entangled polymeric rings and ring-linear blends.

Journal Article Journal of rheology · July 2021 We present a comprehensive experimental rheological dataset for purified entangled ring polystyrenes and their blends with linear chains in nonlinear shear and elongation. In particular, data for shear stress growth coefficient, steady-state shear viscosit ... Full text Cite

Single-Event Spectroscopy and Unravelling Kinetics of Covalent Domains Based on Cyclobutane Mechanophores.

Journal Article Journal of the American Chemical Society · April 2021 Mechanochemical reactions that lead to an increase in polymer contour length have the potential to serve as covalent synthetic mimics of the mechanical unfolding of noncovalent "stored length" domains in structural proteins. Here we report the force-depend ... Full text Cite

Molecular Characterization of Polymer Networks.

Journal Article Chemical reviews · April 2021 Polymer networks are complex systems consisting of molecular components. Whereas the properties of the individual components are typically well understood by most chemists, translating that chemical insight into polymer networks themselves is limited by th ... Full text Cite

Nonlinear Shear Rheology of Entangled Polymer Rings

Journal Article Macromolecules · March 23, 2021 Steady-state shear viscosity (γ˙) of unconcatenated ring polymer melts as a function of the shear rate γ˙ is studied by a combination of experiments, simulations, and theory. Experiments using polystyrenes with Z ≈ 5 and Z ≈ 11 entanglements indicate weake ... Full text Cite

Mechanism Dictates Mechanics: A Molecular Substituent Effect in the Macroscopic Fracture of a Covalent Polymer Network.

Journal Article Journal of the American Chemical Society · March 2021 The fracture of rubbery polymer networks involves a series of molecular events, beginning with conformational changes along the polymer backbone and culminating with a chain scission reaction. Here, we report covalent polymer gels in which the macroscopic ... Full text Cite

Dynamic Coupling in Unentangled Liquid Coacervates Formed by Oppositely Charged Polyelectrolytes.

Journal Article Macromolecules · February 2021 We develop a scaling theory that predicts the dynamics of symmetric and asymmetric unentangled liquid coacervates formed by solutions of oppositely-charged polyelectrolytes. Symmetric coacervates made from oppositely-charged polyelectrolytes consist of pol ... Full text Cite

Tuning Selectivities in Gas Separation Membranes Based on Polymer-Grafted Nanoparticles.

Journal Article ACS nano · December 2020 Polymer membranes are critical to many sustainability applications that require the size-based separation of gas mixtures. Despite their ubiquity, there is a continuing need to selectively affect the transport of different mixture components while enhancin ... Full text Cite

Structure of Polymer-Grafted Nanoparticle Melts.

Journal Article ACS nano · November 2020 The structure of neat melts of polymer-grafted nanoparticles (GNPs) is studied via coarse-grained molecular dynamics simulations. We systematically vary the degree of polymerization and grafting density at fixed nanoparticle (NP) radius and study in ... Full text Cite

Ion Pairing and the Structure of Gel Coacervates.

Journal Article Macromolecules · November 2020 A scaling model for the structure of coacervates is presented for mixtures of oppositely-charged polyelectrolytes of both symmetric and asymmetric charge-densities for different degrees of electrostatic strength and levels of added salt. At low electrostat ... Full text Cite

Understanding Factors Governing Distribution Volume of Ethyl Cellulose-Ethanol to Optimize Ablative Therapy in the Liver.

Journal Article IEEE transactions on bio-medical engineering · August 2020 ObjectiveEthanol ablation, the injection of ethanol to induce necrosis, was originally used to treat hepatocellular carcinoma, with survival rates comparable to surgery. However, efficacy is limited due to leakage into surrounding tissue. To reduc ... Full text Cite

Effects of Tethered Polymers on Dynamics of Nanoparticles in Unentangled Polymer Melts.

Journal Article Macromolecules · August 2020 Polymer-tethered nanoparticles (NPs) are commonly added to a polymer matrix to improve material properties. Critical to the fabrication and processing of such composites is the mobility of the tethered NPs. Here we study the motion of tethered-NPs in unent ... Full text Cite

Stress relaxation in symmetric ring-linear polymer blends at low ring fractions.

Journal Article Macromolecules · March 2020 We combine linear viscoelastic measurements and modelling in order to explore the dynamics of blends of the same-molecular-weight ring and linear polymers in the regime of the low volume fraction (0.3 or lower) of the ring component. The stress relaxation ... Full text Cite

Topological Linking Drives Anomalous Thickening of Ring Polymers in Weak Extensional Flows.

Journal Article Physical review letters · January 2020 Molecular dynamics simulations confirm recent extensional flow experiments showing ring polymer melts exhibit strong extension-rate thickening of the viscosity at Weissenberg numbers Wi≪1. Thickening coincides with the extreme elongation of a minority popu ... Full text Cite

Ten puzzles of the airway surface layer

Conference ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY · August 25, 2019 Link to item Cite

Unexpected Stretching of Entangled Ring Macromolecules.

Journal Article Physical review letters · May 2019 Featured Publication In the melt state at equilibrium, entangled nonconcatenated ring macromolecules adapt more compact conformations compared to their linear analogs and do not form an entanglement network. We show here that, when subjected to uniaxial stretching, they exhibi ... Full text Cite

Quantitative Adjustment to the Molecular Energy Parameter in the Lake-Thomas Theory of Polymer Fracture Energy

Journal Article Macromolecules · April 9, 2019 Featured Publication We present a conceptual framework for adding molecular details of chain extension and force-coupled bond dissociation to the Lake-Thomas model of tear energy in rubbery crack propagation. Incorporating data reported from single-molecule force spectroscopy ... Full text Cite

Helicoidal Patterning of Nanorods with Polymer Ligands.

Journal Article Angewandte Chemie (International ed. in English) · March 2019 Featured Publication Chiral packing of ligands on the surface of nanoparticles (NPs) is of fundamental and practical importance, as it determines how NPs interact with each other and with the molecular world. Herein, for gold nanorods (NRs) capped with end-grafted nonchiral po ... Full text Cite

Mobility of Polymer-Tethered Nanoparticles in Unentangled Polymer Melts.

Journal Article Macromolecules · February 2019 A scaling theory is developed for the motion of a polymer-tethered nanoparticle (NP) in an unentangled polymer melt. We identify two types of scaling regimes depending on the NP diameter d and the size of a grafted polymer chain (tail) R Full text Cite

Roles of mucus adhesion and cohesion in cough clearance.

Journal Article Proc Natl Acad Sci U S A · December 4, 2018 Clearance of intrapulmonary mucus by the high-velocity airflow generated by cough is the major rescue clearance mechanism in subjects with mucoobstructive diseases and failed cilial-dependent mucus clearance, e.g., subjects with cystic fibrosis (CF) or chr ... Full text Link to item Cite

Structure of Liquid Coacervates formed by Oppositely Charged Polyelectrolytes.

Journal Article Macromolecules · December 2018 We develop a scaling theory and perform molecular dynamic simulations of weakly interacting coacervates with electrostatic interaction energy per charge less than thermal energy kT. Such liquid coacervates formed by oppositely charged polyelectrolyt ... Full text Cite

Elastic-Plastic Transformation of Polyelectrolyte Complex Hydrogels from Chitosan and Sodium Hyaluronate.

Journal Article Macromolecules · November 2018 Hydrogels formed by polyelectrolyte complexation (PEC) of oppositely charged biopolymers, free of any chemical additives, are promising biomaterials. In this work, the mechanical behavior of hydrogels consisting of positively charged chitosan and negativel ... Full text Cite

Nanorheology of Entangled Polymer Melts

Journal Article Physical Review Letters · 2018 We use molecular simulations to probe the local viscoelasticity of an entangled polymer melt by tracking the motion of embedded nonsticky nanoparticles (NPs). As in conventional microrheology, the generalized Stokes-Einstein relation is employed to extract ... Full text Cite

Strong, Tough, Stretchable, and Self-Adhesive Hydrogels from Intrinsically Unstructured Proteins

Journal Article Advanced Materials · 2017 An experiment has demonstrated that genetically engineered unstructured proteins with covalent and reversible crosslinking (due to metal coordination and hydrophobic interactions) yield hydrogels with extremely high strength, toughness, stretchability, and ... Full text Cite

Programming molecular self-assembly of intrinsically disordered proteins containing sequences of low complexity

Journal Article Nature Chemistry · 2017 A programmable model of membraneless organelles comprised of intrinsically disordered proteins (IDPs) containing sequences of low complexity has now been developed. The rules governing the assembly of archetypal IDPs into biologically inspired mixed, layer ... Full text Cite

Flory theory of randomly branched polymers

Journal Article Soft Matter · 2017 Randomly branched polymer chains (or trees) are a classical subject of polymer physics with connections to the theory of magnetic systems, percolation and critical phenomena. More recently, the model has been reconsidered for RNA, supercoiled DNA and the c ... Full text Cite

Nanoparticle Motion in Entangled Melts of Linear and Nonconcatenated Ring Polymers

Journal Article Macromolecules · 2017 The motion of nanoparticles (NPs) in en-tangled melts of linear polymers and nonconcatenated ring polymers are compared by large-scale molecular dynamics simulations. The comparison provides a paradigm for the effects of polymer architecture on the dynamic ... Full text Cite

Polymers at Liquid/Vapor Interface

Journal Article ACS Macro Letters · 2017 Full text Cite

Enhanced nanochannel translocation and localization of genomic DNA molecules using three-dimensional nanofunnels

Journal Article Nature Communications · 2017 The ability to precisely control the transport of single DNA molecules through a nanoscale channel is critical to DNA sequencing and mapping technologies that are currently under development. Here we show how the electrokinetically driven introduction of D ... Full text Cite

A Rheological Study of the Association and Dynamics of MUC5AC Gels

Journal Article Biomacromolecules · 2017 The details of how the mucus hydrogel forms from its primary structural component, mucin polymers, remain incompletely resolved. To explore this, we use a combination of macrorheology and single particle tracking to investigate the bulk and microscopic mec ... Full text Cite

Single-stranded nucleic acid elasticity arises from internal electrostatic tension

Journal Article Proceedings of the National Academy of Sciences · 2017 Understanding of the conformational ensemble of flexible polyelectrolytes, such as single-stranded nucleic acids (ssNAs), is complicated by the interplay of chain backbone entropy and salt-dependent electrostatic repulsions. Molecular elasticity measuremen ... Full text Cite

Programming molecular self-assembly of intrinsically disordered proteins

Conference ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY · March 13, 2016 Link to item Cite

Solvent-free, supersoft and superelastic bottlebrush melts and networks

Journal Article Nature Materials · 2016 Polymer gels are the only viable class of synthetic materials with a Young’s modulus below 100 kPa conforming to biological applications, yet those gel properties require a solvent fraction. The presence of a solvent can lead to phase separation, evaporati ... Full text Cite

Molecular structure of Bottlebrush polymers in melts

Journal Article Science Advances · 2016 Bottlebrushes are fascinating macromolecules that display an intriguing combination of molecular and partic-ulate features having vital implications in both living and synthetic systems, such as cartilage and ultrasoft elastomers. However, the progress in ... Full text Cite

Tension Amplification in Tethered Layers of Bottle-Brush Polymers

Journal Article Macromolecules · 2016 Molecular dynamics simulations of a coarse-grained bead–spring model have been used to study the effects of molecular crowding on the accumulation of tension in the backbone of bottle-brush polymers tethered to a flat substrate. The number of bottle-brushe ... Full text Cite

Surface-Anchored Poly(N-isopropylacrylamide) Orthogonal Gradient Networks

Journal Article Macromolecules · 2016 We present a versatile synthetic route leading toward generating surface-attached polyacrylamide gels, in which the cross-link density varies continuously and gradually across the substrate in two orthogonal directions. We employ free radical polymerizatio ... Full text Cite

Multicore expandable microbubbles: Controlling density and expansion temperature

Journal Article Polymer (United Kingdom) · 2016 Stable microbubbles can be prepared by evaporation of a liquid core inside an expandable polymeric shell. To control the expansion temperature and the size of resulting microbubbles, we prepared polymeric microcapsules that contain multiple liquids in thei ... Full text Cite

Network dynamics in nanofilled polymers

Journal Article Nature Communications · 2016 It is well accepted that adding nanoparticles (NPs) to polymer melts can result in significant property improvements. Here we focus on the causes of mechanical reinforcement and present rheological measurements on favourably interacting mixtures of spheric ... Full text Cite

Surface patterning of nanoparticles with polymer patches

Journal Article Nature · 2016 Patterning of colloidal particles with chemically or topographically distinct surface domains (patches) has attracted intense research interest1–3. Surface-patterned particles act as colloidal analogues of atoms and molecules4,5 , serve as model systems in ... Full text Cite

Self-Similar Conformations and Dynamics in Entangled Melts and Solutions of Nonconcatenated Ring Polymers

Journal Article Macromolecules · 2016 A scaling model of self-similar conformations and dynamics of nonconcatenated entangled ring polymers is developed. Topological constraints force these ring polymers into compact conformations with fractal dimension df = 3 that we call fractal loopy globul ... Full text Cite

Elastin-like Polypeptide Diblock Copolymers Self-Assemble into Weak Micelles

Journal Article Macromolecules · 2015 The self-assembly of synthetic diblock copolymers has been extensively studied experimentally and theoretically. In contrast, self-assembly of polypeptide diblock copolymers has so far been mostly studied experimentally. We discovered that the theory devel ... Full text Cite

Opportunities in theoretical and computational polymeric materials and soft matter

Journal Article Soft Matter · 2015 Soft materials are abundant in nature and ubiquitous in living systems. Elucidating their multi-faceted properties and underlying mechanisms is not only theoretically challenging and important in its own right, but also serves as the foundation for new mat ... Full text Cite

Strong Selective Adsorption of Polymers

Journal Article Macromolecules · 2015 A scaling theory is developed for selective adsorption of polymers induced by the strong binding between specific monomers and complementary surface adsorption sites. By ?selective? we mean specific attraction between a subset of all monomers, called ?stic ... Full text Cite

Hopping diffusion of nanoparticles in polymer matrices

Journal Article Macromolecules · 2015 We propose a hopping mechanism for diffusion of large nonsticky nanoparticles subjected to topological constraints in both unentangled and entangled polymer solids (networks and gels) and entangled polymer liquids (melts and solutions). Probe particles wit ... Full text Cite

Conformations of a long polymer in a melt of shorter chains: Generalizations of the Flory theorem

Journal Article ACS Macro Letters · 2015 Large-scale simulations of the swelling of a long N-mer in a melt of chemically identical P-mers are used to investigate a discrepancy between theory and experiments. Classical theory predicts an increase of probe chain size R ∼ P-0.18 with decreasing degr ... Full text Cite

The role of crystallinity in SWCNT-polyetherimide nanocomposites

Journal Article Composites Science and Technology · 2015 Two all-aromatic, high-performance poly(etherimide)s ODPA-P3 (I) and BPDA-P3 (II) are studied as a function of SWCNT loading. Polyetherimide I is amorphous but SWCNTs nucleate crystallization during imidization to produce a nanocomposite (nc-I) with SWCNTs ... Full text Cite

Nanocapillarity-mediated magnetic assembly of nanoparticles into ultraflexible filaments and reconfigurable networks

Journal Article Nature Materials · 2015 The fabrication of multifunctional materials with tunable structure and properties requires programmed binding of their building blocks. For example, particles organized in long-ranged structures by external fields can be bound permanently into stiff chain ... Full text Cite

Soft Poly(dimethylsiloxane) Elastomers from Architecture-Driven Entanglement Free Design

Journal Article Advanced Materials · 2015 Soft, solvent-free poly(dimethylsiloxane) elastomers are fabricated by a one-step process via crosslinking bottlebrush polymers. The bottlebrush architecture prevents the formation of entanglements, resulting in elastomers with precisely controllable low m ... Full text Cite

Universal behavior of hydrogels confined to narrow capillaries

Journal Article Scientific Reports · 2015 Flow of soft matter objects through one-dimensional environments is important in industrial, biological and biomedical systems. Establishing the underlying principles of the behavior of soft matter in confinement can shed light on its performance in many m ... Full text Cite

The relationship of mucus concentration (hydration) to mucus osmotic pressure and transport in chronic bronchitis

Journal Article American Journal of Respiratory and Critical Care Medicine · 2015 RATIONALE: Chronic bronchitis (CB) is characterized by persistent cough and sputum production. Studies were performed to test whether mucus hyperconcentration and increased partial osmotic pressure, in part due to abnormal purine nucleotide regulation of i ... Full text Cite

SWCNT induced crystallization in amorphous and semi-crystalline poly(etherimide)s: Morphology and thermo-mechanical properties

Journal Article Polymer (United Kingdom) · 2014 In this study we contrast the behavior of an amorphous polyetherimide (ODPA-P3) with that of a semi-crystalline one (BPDA-P3) on introducing single-wall carbon nanotubes (SWCNTs; 0.1-4.4 vol.%). The SWCNTs act as a nucleating agent and induce crystallinity ... Full text Cite

Rouse mode analysis of chain relaxation in homopolymer melts

Journal Article Macromolecules · 2014 \textlessp\textgreaterLarge-scale molecular dynamics simulations are used to study the internal relaxations of chains in nanoparticle (NP)/polymer composites.\textless/p\textgreater ... Full text Cite

RAFT polymerization of temperature- and salt-responsive block copolymers as reversible hydrogels

Journal Article Polymer (United Kingdom) · 2014 Reversible-addition fragmentation chain transfer (RAFT) polymerization enabled the synthesis of novel, stimuli-responsive, AB and ABA block copolymers. The B block contained oligo(ethylene glycol) methyl ether methacrylate (OEG) and was permanently hydroph ... Full text Cite

Copolymerization of metal nanoparticles: A route to colloidal plasmonic copolymers

Journal Article Angewandte Chemie - International Edition · 2014 The resemblance between colloidal and molecular polymerization reactions is very useful in fundamental studies of polymerization reactions, as well as in the development of new nanoscale systems with desired properties. Future applications of colloidal pol ... Full text Cite

Lubrication by polyelectrolyte brushes

Journal Article Macromolecules · 2014 We develop a scaling model relating the friction forces between two polyelectrolyte brushes sliding over each other to the separation between grafted surfaces, number of monomers and charges per chain, grafting density of chains, and solvent quality. We de ... Full text Cite

Microfluidic fabrication of stable gas-filled microcapsules for acoustic contrast enhancement

Journal Article Langmuir · 2013 We introduce a facile approach for the production of gas-filled microcapsules designed to withstand high pressures. We exploit microfluidics to fabricate water-filled microcapsules that are then externally triggered to become gas-filled, thus making them m ... Full text Cite

SWCNT induced crystallization in an amorphous all-aromatic poly(ether imide)

Journal Article Macromolecules · 2013 We have selected two amorphous all-arom. poly(ether imide)s with similar chem. structures but with different backbone geometries as matrixes for SWCNT-based nanocomposites. Up to 4.4 vol. %, SWCNTs could be incorporated using an in situ polymn. method. N ... Full text Cite

A system for acoustical and optical analysis of encapsulated microbubbles at ultrahigh hydrostatic pressures

Journal Article Citation: Review of Scientific Instruments The Journal of the Acoustical Society of America REVIEW OF SCIENTIFIC INSTRUMENTS · 2013 Acoustics are commonly used for borehole (i.e., oil well) imaging applications, under conditions where temperature and pressure reach extremes beyond that of conventional medical ultrasonics. Re-cently, there has been an interest in the application of enca ... Full text Cite

Self-healing of unentangled polymer networks with reversible bonds

Journal Article Macromolecules · 2013 Self-healing polymeric materials are systems that after damage can revert to their original state with full or partial recovery of mechanical strength. Using scaling theory we study a simple model of autonomic self-healing of unentangled polymer networks. ... Full text Cite

Structural transitions in nanoparticle assemblies governed by competing nanoscale forces

Journal Article Journal of the American Chemical Society · 2013 Assembly of nanoscale materials from nanoparticle (NP) building blocks relies on our understanding of multiple nanoscale forces acting between NPs. These forces may compete with each other and yield distinct stimuli-responsive self-assembled nanostructures ... Full text Cite

Perfect mixing of immiscible macromolecules at fluid interfaces

Journal Article Nature Materials · 2013 The difficulty of mixing chemically incompatible substances–in particular macromolecules and colloidal particles–is a canonical problem limiting advances in fields ranging from health care to materials engineering. Although the self-assembly of chemically ... Full text Cite

Colloidal analogs of molecular chain stoppers

Journal Article Proceedings of the National Academy of Sciences · 2013 A similarity between chemical reactions and self-assembly of nanoparticles offers a strategy that can enrich both the synthetic chemistry and the nanoscience fields. Synthetic methods should enable quantitative control of the structural characteristics of ... Full text Cite

Viscosity of ring polymer melts

Journal Article ACS Macro Letters · 2013 We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts ?0,linear to their ring counterparts ?0,ring at ... Full text Cite

A Periciliary Brush Promotes the Lung Health by Separating the Mucus Layer from Airway Epithelia

Journal Article · August 24, 2012 Mucus clearance is the primary defense mechanism that protects airways from inhaled infectious and toxic agents. In the current gel-on-liquid mucus clearance model, a mucus gel is propelled on top of a " watery " periciliary layer surrounding the cilia. Ho ... Full text Link to item Cite

Polyelectrolytes in biology and soft matter

Journal Article Soft Matter · 2012 Many important biological macromole-cules, such as DNA, RNA, polypeptides, and polysaccharides, as well as large number of artificial macromolecules, such as poly(styrene sulfonate) (PSS) and pol-yacrylic acid (PAA), are highly charged polyelectrolytes. Co ... Full text Cite

Ionic strength dependence of polyelectrolyte brush thickness

Journal Article Soft Matter · 2012 Intramolecular repulsion between charged monomers imposes intrinsic tension in polyion, modifies its elasticity, and changes the dependence of polyelectrolyte brush thickness on salt concentration. We demonstrate that intrinsic polyion tension gives rise t ... Full text Cite

Bond tension in tethered macromolecules

Journal Article Macromolecules · 2011 The paper presents scaling analysis of mechanical tension generated in densely branched macromolecules tethered to a solid substrate with a short linker. Steric repulsion between branches results in z-fold amplification of tension in the linker, where z is ... Full text Cite

Mobility of nonsticky nanoparticles in polymer liquids

Journal Article Macromolecules · 2011 We use scaling theory to derive the time dependence of the mean-square displacement 〈Δr(2)〉 of a spherical probe particle of size d experiencing thermal motion in polymer solutions and melts. Particles with size smaller than solution correlation length ξ u ... Full text Cite

2037-Pos Board B23 Mechanism of Flexibility Control for ATP Access of Hepatitis C Virus NS3 Helicase Computational Investigation of the Effect of Ions on the Secondary Struc- ture of Small Peptides

Journal Article Biophysj · 2011 Hepatitis C virus NS3 helicase couples ATP binding and hydrolysis to polynu-cleotide unwinding. Understanding its regulation mechanism of ATP binding will facilitate targeting of ATP binding site for potential hepatitis C treatment. T324, a residue connect ... Full text Cite

The use of functionalized nanoparticles as non-specific compatibilizers for polymer blends

Journal Article Polymers for Advanced Technologies · 2011 The ability to form blends of polymers offers the opportunity of creating a new class of materials with enhanced properties. In addition to the polymer components, recent advances in nanoengineering have resulted in the development of nanosized inorganic p ... Full text Cite

Step-Growth Polymerization of Inorganic Nanoparticles

Journal Article · July 9, 2010 Self-organization of nanoparticles is an efficient strategy for producing nanostructures with complex, hierarchical architectures. The past decade has witnessed great progress in nanoparticle self-assembly, yet the quantitative prediction of the architectu ... Full text Link to item Cite

Spontaneous and specific activation of chemical bonds in macromolecular fluids

Journal Article Journal of the American Chemical Society · 2010 Mechanical activation of chemical bonds typically involves the application of external forces, which implies a broad distribution of bond tensions. We demonstrate that controlling the flow profile of a macromolecular fluid generates and delineates mechanic ... Full text Cite

Chains Are More Flexible Under Tension

Journal Article Macromolecules · 2010 The mechanical response of networks, gels, and brush layers is a manifestation of the elastic properties of the individual macromolecules. Furthermore, the elastic response of macromolecules to an applied force is the foundation of the single-molecule forc ... Full text Cite

Computing free energies of protein conformations from explicit solvent simulations

Journal Article Methods · 2010 We report a fully general technique addressing a long standing challenge of calculating conformational free energy differences between various states of a polymer chain from simulations using explicit solvent force fields. The main feature of our method is ... Full text Cite

Tension amplification in molecular brushes in solutions and on substrates

Journal Article Journal of Physical Chemistry B · 2009 Molecular bottle-brushes are highly branched macromolecules with side chains densely grafted to a long polymer backbone. The brush-like architecture allows focusing of the side-chain tension to the backbone and its amplification from the pico-Newton to nan ... Full text Cite

End-monomer dynamics in semiflexible polymers

Journal Article Macromolecules · 2009 Spurred by an experimental controversy in the literature, we investigate the end-monomer dynamics of semiflexible polymers through Brownian hydrodynamic simulations and dynamic mean-field theory. Precise experimental observations over the last few years of ... Full text Cite

Amplification of tension in branched macromolecules

Journal Article Physical Review Letters · 2009 We propose a method for the design of branched macromolecules that are capable of building up high tension ( approximately nN) in their covalent bonds without applying an external force. The tension is self-generated due to repulsion between branches and d ... Full text Cite

Concentration regimes in solutions of polyelectrolyte stars

Journal Article Macromolecules · 2008 Abstract: We present a scaling theory for solutions of star-branched polyelectrolytes in different concentration regimes. We distinguish between two cases of counterion distribution around the star arms and describe differences in the structure of stars wi ... Full text Cite

Effect of the soluble block size on spherical diblock copolymer micelles

Journal Article Macromolecules · 2008 While the effect of the insoluble block length on micelle properties is well understood, the effect of the soluble block is still controversial. We, therefore, have investigated the effect of the molecular weight of the soluble block on the critical micell ... Full text Cite

Unexpected power-law stress relaxation of entangled ring polymers

Journal Article Nature Materials · 2008 After many years of intense research, most aspects of the motion of entangled polymers have been understood. Long linear and branched polymers have a characteristic entanglement plateau and their stress relaxes by chain reptation or branch retraction, resp ... Full text Cite

PH-induced release of polyanions from multilayer films

Journal Article Physical Review Letters · 2008 We discovered pH-induced selective desorption and readsorption of weakly acidic polymers from polyacid or polybase layer-by-layer films. In situ attenuated total reflection Fourier transform infrared spectroscopy confirms the selectivity of polyacid releas ... Full text Cite

Long-range correlations in a polymer chain due to its connectivity

Journal Article Macromolecules · 2008 The analysis of intrachain monomeric interactions reveals a new effect in the description of polymer conformations in dilute theta-solutions, semidilute solutions, and melts. The chain connectivity modifies the effective monomeric interaction, which result ... Full text Cite

"Supramolecular" assembly of gold nanorods end-terminated with polymer "pom-poms": Effect of pom-pom structure on the association modes

Journal Article Journal of the American Chemical Society · 2008 We report a predefined self-organization of gold nanorods (NRs) end-terminated with multiple polymer arms ("pom-poms") in higher-order structures. The assembly of polymer-tethered NRs was controlled by changing the structure of the polymer pom-poms. We sho ... Full text Cite

Flory theorem for structurally asymmetric mixtures

Journal Article Physical Review Letters · 2007 The generalization of the Flory theorem for structurally asym. mixts. was derived and tested by direct visualization of conformational transformations of brushlike macromols. embedded in a melt of linear chains. Swelling of a brush mol. was shown to be con ... Full text Cite

Self-assembly of metal-polymer analogues of amphiphilic triblock copolymers

Journal Article Nature Materials · 2007 Organized arrays of anisotropic nanoparticles show electronic and optical properties that originate from the coupling of shape-dependent properties of the individual nanorods. The organization of nanorods in a controllable and predictable way provides a ro ... Full text Cite

Rouse dynamics of polyelectrolyte solutions: Molecular dynamics study

Journal Article Macromolecules · 2007 We performed molecular dynamics simulations of dilute and semidilute polyelectrolyte solutions without hydrodynamic interactions to study Rouse dynamics of polyelectrolytes. Polyelectrolyte solutions are modeled by an ensemble of bead-spring chains of char ... Full text Cite

Molecular pressure sensors

Journal Article Advanced Materials · 2007 Monitoring of brush-like macromolecules as they change their shape in response to variations in the film pressure during flow were reported. After appropriate calibration, these molecular sensors can be used to gauge both the pressure gradient and the fric ... Full text Cite

A physical linkage between cystic fibrosis airway surface dehydration and Pseudomonas aeruginosa biofilms

Journal Article Proceedings of the National Academy of Sciences · November 28, 2006 A vexing problem in cystic fibrosis (CF) pathogenesis has been to explain the high prevalence of Pseudomonas aeruginosa biofilms in CF airways. We speculated that airway surface liquid (ASL) hyperabsorption generates a concentrated airway mucus that intera ... Full text Link to item Cite

Flow-enhanced epitaxial ordering of brush-like macromolecules on graphite

Journal Article Langmuir · 2006 Long-range orientational order in monolayers of brush-like macromolecules was achieved during spreading of a polymer melt on the surface of highly oriented pyrolytic graphite. The combination of wetting-induced flow and epitaxial adsorption of poly(n-butyl ... Full text Cite

Reversible morphological transitions of polystyrene-b-polyisoprene micelles

Journal Article Macromolecules · 2006 Reversible morphological transitions of diblock copolymer micelles in dilute solutions were monitored by light scattering and atomic force microscopy for two different polymer samples near the calculated morphological boundaries. These transitions were ind ... Full text Cite

Counterion-correlation-induced attraction and necklace formation in polyelectrolyte solutions: Theory and simulations

Journal Article Macromolecules · 2006 We have developed a necklace model of hydrophobic polyelectrolytes in which the necklace structure consisting of polymeric globules (beads) connected by extended sections of the chain (strings of monomers) appears as a result of the counterion condensation ... Full text Cite

Regimes of conformational transitions of a diblock polyampholyte

Journal Article Macromolecules · 2006 The conformational properties of symmetric flexible diblock polyampholytes are investigated by scaling theory and molecular dynamics simulations. The electrostatically driven coil-globule transition of a symmetric diblock polyampholyte is found to consist ... Full text Cite

Adsorption-induced scission of carbon-carbon bonds

Journal Article Nature · 2006 Covalent carbon–carbon bonds are hard to break. Their strength is evident in the hardness of diamonds1,2 and tensile strength of polymeric fibres3–6; on the single-molecule level, it manifests itself in the need for forces of several nanonewtons to extend ... Full text Cite

Solution properties of a fluorinated alkyl methacrylate polymer in carbon dioxide

Journal Article Macromolecules · 2006 The solution properties of a fluorinated alkyl methacrylate, poly(1,1,2,2-tetrahydroperfluorooctyl methacrylate) (PFOMA), in liquid and supercritical carbon dioxide (CO2) were studied by static and dynamic light scattering. The solvent quality of CO2 was f ... Full text Cite

Theory of polyelectrolytes in solutions and at surfaces

Journal Article Progress in Polymer Science (Oxford) · 2005 Polyelectrolytes are polymers carrying either positively or negatively charged ionizable groups. The properties of these polymers in solutions and at charged surfaces depend on the fraction of dissociated ionic groups, solvent quality for polymer backbone, ... Full text Cite

Molecular visualization of conformation-triggered flow instability

Journal Article Physical Review Letters · 2005 A new type of flow fingering instability was obsd. in monolayer-thick acrylic graft polymer films as they spread on a solid substrate. Tracing the movement of individual mols. by at. force microscopy enabled us to follow the development of the flow instabi ... Full text Cite

Diblock copolymer micelles in a dilute solution

Journal Article Macromolecules · 2005 We performed theor. and exptl. investigations of dil. solns. of micelles of neutral amorphous diblock copolymers in selective solvents. The ranges of thermodn. stability of spherical, cylindrical, and lamellar morphologies along with the equil. sizes and a ... Full text Cite

Scaling theory of diblock polyampholyte solutions

Journal Article Macromolecules · 2005 We have developed a scaling theory for a salt-free solution of diblock polyampholytes. A charge-symmetric diblock polyampholyte chain with equally charged positive and negative blocks collapses into a globule. This collapse is driven by the electrostatic a ... Full text Cite

Explanation of anomalous scaling of swollen entangled chains

Journal Article Macromolecules · 2005 The unexpected scaling dependence R-n similar to n(0.72) of the size Rn of the chain section with n monomers observed in recent numerical simulations of a swollen network and globule is explained on the basis of the slip-tube model. We demonstrate that the ... Full text Cite

Polymers: A Multitude of Macromolecules”

Journal Article Nature Materials · 2004 Cite

Wormlike micelles of block copolymers: Measuring the linear density by AFM and light scattering

Journal Article Macromolecules · 2004 Wormlike micelles can form from polystyrene-b-polyisoprene copolymers in heptane as selective solvent for polyisoprene. We have measured the aggregation number per unit length of polystyrene-b-polyisoprene wormlike micelles by light scattering and AFM. The ... Full text Cite

Polyampholytes

Journal Article Journal of Polymer Science, Part B: Polymer Physics · 2004 : Polyampholytes are charged polymers with both positively and negatively charged groups. The conformation of these polymers in solutions strongly depends on the distribution of charged monomers along the polymer backbone and their environ- ment. In this r ... Full text Cite

Molecular motion in a spreading precursor film

Journal Article Physical Review Letters · 2004 Spreading of a polymer drop on a solid substrate was monitored with mol. resoln. Three characteristic rates, i.e., the spreading rate of the precursor film Dspread=(3.9±0.2)×103 nm2/s, the flow-induced diffusion rate of mols. within the film Dinduced=1.3±0 ... Full text Cite

Light scattering study of polydimethyl siloxane in liquid and supercritical carbon dioxide

Journal Article Journal of Physical Chemistry A · 2004 In this paper, we report the results of static and dynamic light scattering investigations of polydimethyl siloxane (PDMS) solutions in both liquid and supercritical carbon dioxide (CO2). This study was performed below the theta point and provides quantita ... Full text Cite

Monte Carlo simulation of homopolymer chains. I. Second virial coefficient Microscopic theory of the dynamics of polymeric liquids: General formulation of a mode–mode-coupling approach Polymer reference interaction site model theory: New molecular closures for phase separating fluids and alloys Monte Carlo simulation of homopolymer chains. I. Second virial coefficient

Journal Article The Journal of Chemical Physics Journal of Chemical Physics The Journal of Chemical Physics II The Journal of Chemical Physics The Journal of Chemical Physics The Journal of Chemical Physics Journal of Chemical Physics · 2003 The second virial coefficient, A 2 , is evaluated between pairs of short chain molecules by direct simulations using a parallel tempering Monte Carlo method where the centers of mass of the two molecules are coupled by a harmonic spring. Three off-lattice ... Full text Cite

Molecular dynamics simulations of polyelectrolyte solutions: Osmotic coefficient and counterion condensation

Journal Article Macromolecules · 2003 Osmotic coefficients and counterion distribution functions of rodlike and flexible polyelectrolyte chains have been studied using molecular dynamics simulations of multichain systems with explicit counterions in salt-free solutions. Using the counterion de ... Full text Cite

Molecular dynamics simulations of polyelectrolyte solutions: Nonuniform stretching of chains and scaling behavior

Journal Article Macromolecules · 2003 We present the results of molecular dynamics simulations of polyelectrolyte solutions in near-?-solvent conditions for polymer backbone. Polyelectrolyte solutions are modeled as an ensemble of bead-spring chains of charged Lennard-Jones particles with expl ... Full text Cite

Microscopic theory of linear, entangled polymer chains under rapid deformation including chain stretch and convective constraint release

Journal Article Journal of Rheology · 2003 ... At low shear rates the stress increases linearly with shear rate, at intermediate rates there is a ... This holds until where at these very high rates the assumption that the chains are at ... by linear oscillatory shear measurements or were set to uni ... Full text Cite

Adsorption of hydrophobic polyelectrolytes at oppositely charged surfaces

Journal Article Macromolecules · 2002 We develop a scaling theory of adsorption of necklace-like hydrophobic polyelectrolytes at an oppositely charged hydrophilic and hydrophobic surfaces. At low surface charge densities we predict a two-dimensional adsorbed layer with thickness determined by ... Full text Cite

Dynamics of entangled associating polymers with large aggregates

Journal Article Macromolecules · 2002 We develop a theory for the dynamics in entangled solutions of associating polymers with many stickers per chain. The stickers strongly associate and form large aggregates that control both the equilibrium structure of the system and its dynamics. The asso ... Full text Cite

Elasticity of polymer networks

Journal Article Macromolecules · 2002 We develop and solve a new molecular model for nonlinear elasticity of entangled polymer networks. This model combines and generalizes several succeseful ideas introduced over the years in the field of the rubber elasticity. The topological constraints imp ... Full text Cite

Polymeric nanogels produced via inverse microemulsion polymerization as potential gene and antisense delivery agents

Journal Article Journal of the American Chemical Society · 2002 Polymeric nanogel vectors were developed for cellular gene and antisense delivery. Inverse microemulsion polymerization was utilized to synthesize biocompatible nanogels with controlled size, morphology, and composition. The chemical composition, size, pol ... Full text Cite

Structure of adsorbed polyampholyte layers at charged objects

Journal Article Macromolecules · 2001 We have developed a theory of adsorption of polyampholyte chains at a charged planar surface and a charged spherical particle from dilute low salt solutions. The adsorption is due to the polarization of polyampholyte chains in the external electric field c ... Full text Cite

Dynamics of entangled solutions of associating polymers

Journal Article Macromolecules · 2001 The process of making and breaking reversible bonds between associating groups (stickers) controls the dynamics of associating polymers. We develop a theory of “sticky reptation” to model the dynamics of entangled solutions of associating polymers with man ... Full text Cite

Adsorption isotherms of polyampholytes at charged spherical particles

Journal Article Journal of Physical Chemistry B · 2001 We develop a scaling theory of adsorption of polyampholyte chains at charged spherical particles from dilute low salt solutions. The adsorption is due to the polarization of polyampholyte chains in the electric field created by charged particles. The expre ... Full text Cite

Adsorption of polyelectrolytes at oppositely charged surfaces

Journal Article Macromolecules · 2001 We have developed a scaling theory of polyelectrolyte adsorption at an oppositely charged surface. At low surface charge densities, we predict two-dimensional adsorbed layers with thickness determined by the balance between electrostatic attraction to the ... Full text Cite

Adsorption of a polyampholyte on a charged spherical particle

Journal Article European Physical Journal E · 2001 We develop a scaling theory for a single polyampholyte chain adsorbed$$non a charged spherical particle in a theta-solvent. Adsorption of$$na polyampholyte molecule is doe to its polarization in the electrostatic$$nfield of the particle. For large particle ... Full text Cite

Counterion phase transitions in dilute polyelectrolyte solutions

Journal Article Physical Review Letters · 2001 In dilute solutions of rodlike polyelectrolytes some counterions are distributed far from polyions while others are located in their vicinity in the regions of cylindrical symmetry of the electrostatic potential. For these cylindrical regions around rodlik ... Full text Cite

Counterion condensation and phase separation in solutions of hydrophobic polyelectrolytes

Journal Article Macromolecules · 2001 We have developed a theory of counterion condensation in solutions of hydrophobic polyelectrolytes. In the framework of Oosawa’s two-zone model we demonstrate that solutions of necklaces can be unstable with respect to phase separation. This phase separati ... Full text Cite

Unexpected scenario of glass transition in polymer globules: An exactly enumerable model

Journal Article Physical Review Letters · 2000 We introduce a lattice model of glass transition in polymer globules. This model exhibits ergodicity breaking in which the disjoint regions of phase space do not arise uniformly, but as small chambers whose number increases exponentially with polymer densi ... Full text Cite

Adsorption of Polyelectrolytes at an Oppositely Charged Surface

Journal Article · 2000 We develop a scaling theory of polyelectrolyte adsorption at an oppositely charged surface. At low surface charge densities, the thickness of the adsorbed layer is determined by the balance between electrostatic attraction to the charged surface and chain ... Cite

Hydrophobically modified polyelectrolytes in dilute salt-free solutions

Journal Article Macromolecules · 2000 The universal diagram of states of hydrophobically modified polyelectrolytes in dilute salt-free solutions is calculated in the framework of the scaling approach. The equilibrium conformations of these polymers were classified using two parameters geometri ... Full text Cite

Rheological models based on the double reptation mixing rule: The effects of a polydisperse environment

Journal Article Journal of Rheology · 2000 We present a comparison of various rheological models based on the double reptation concept, which relates linear viscoelastic data to molecular-weight distribution in order to determine the most efficient way to describe polydispersity effects. We have us ... Full text Cite

Associations leading to formation of reversible networks and gels

Other · 1999 One of the most important properties of associative polymers is their ability to form reversible networks and gels. The issue of whether or not the reversible gelation of associative polymers is a thermodynamic transition has not been settled yet. At the s ... Full text Cite

Long-range multichain adsorption of polyampholytes on a charged surface

Journal Article Macromolecules · 1999 We develop a theory of the adsorption of many polyampholyte chains on a charged surface. The adsorption is due to the polarization of polyampholyte chains in the external electric field created by the charged surface. The equilibrium polymer density profil ... Full text Cite

Hydrophobic Polyelectrolytes

Journal Article Macromolecules · 1999 We present a scaling model of hydrophobic polyelectrolytes. In dilute salt-free solutions these polymers have a necklacelike shape with compact beads joined by narrow strings. This necklacelike structure manifests itself in the unique scaling laws in semid ... Full text Cite

Electrophoresis of polyampholytes

Journal Article Journal of Chemical Physics · 1998 We consider the motion and the deformation of Gaussian polyampholytes in free flow electrophoresis, i.e., in an applied external electric field. The electrophoretic mobility and the deformation of the chains are calculated in the linear regime, as function ... Full text Cite

Thermoreversible gelation in solutions of associative polymers. 1. Statics

Journal Article Macromolecules · 1998 An equilibrium mean?field theory for reversible network formation in solutions of associative polymers is presented. We study polymer solutions with many associating groups per chain and consider pairwise association of these groups. A simple analytical ex ... Full text Cite

Thermoreversible gelation in solutions of associating polymers. 2. Linear dynamics

Journal Article Macromolecules · 1998 Viscoelastic properties of reversible networks formed in solutions of associating polymers are considered theoretically in the Rouse?Zimm (unentangled) regime. It is shown that the dynamics is governed primarily by the network strand size and by the effect ... Full text Cite

Dynamics of strongly entangled polymer systems: Activated reptation

Journal Article European Physical Journal B · 1998 The effect of excluded-volume interactions on the reptation dynamics of long polymer chains is considered theoretically. It is shown that interactions give rise to an exponential increase of the reptation time, tau(rep) similar to exp[(n/n*)(2/3)], if poly ... Full text Cite

Polyampholyte solutions between charged surfaces: Debye–Huckel theory Adsorption of a polyelectrolyte chain to a charged surface Polyampholyte solutions between charged surfaces: Debye–Huckel theory

Journal Article The Journal of Chemical Physics The Journal of Chemical Physics The Journal of Chemical Physics The Journal of Chemical Physics Journal of Chemical Physics Colligative Properties The Journal of Chemical Physics The Journal of Chemical Physics · 1998 We calculate the interaction between two identically charged surfaces immersed in a polyampholyte solution in the framework of the linear response approximation. In the case of the randomly charged polyampholyte with equal fractions of positively f ϩ and n ... Full text Cite

Polyelectrolyte-Gelatin Complexation: Light-Scattering Study

Journal Article Macromolecules · June 2, 1997 Complex formation between negatively charged polyelectrolytes and a net negatively charged polyampholyte (gelatin) has been characterized by light scattering. The two polyanions studied are sodium poly(styrenesulfonate) (NaPSS) and sodium poly(2-acrylamido ... Full text Link to item Cite

Topologically Induced Glass Transition in Freely Rotating Rods

Journal Article Journal de Physique I · 1997 We present a simple minimal model which allows numerical and analytical study of a glass transition. This is a model of rigid rods with fixed centers of rotation. The rods can rotate freely but cannot cross each other. The ratio l of the length of the rods ... Full text Cite

Extraction of a hydrophilic compound from water into liquid CO2 using dendritic surfactants

Journal Article Nature · 1997 Dendrimers are well defined, highly branched polymers(1-5) that adopt a roughly spherical, globular shape in solution, Their cores are relatively loosely packed and can trap guest molecules(5-7), and by appropriate functionalization of the branch tips the ... Full text Cite

Long-range effects on polymer diffusion induced by a bounding interface

Journal Article Physical Review Letters · 1997 We have measured the diffusion of deuterated polystyrene of molecular weight 90 x 10(3) in various matrices of hydrogenated polystyrene as a function of distance from an attractive interface, oxide-covered silicon. Surprisingly long-range effects are obser ... Full text Cite

Cascade of Transitions of Polyelectrolytes in Poor Solvents

Journal Article Macromolecules · August 4, 1996 We develop a scaling model for the dilute solution conformation of a uniformly charged polymer in a poor solvent. We find that there is a range of temperatures and charge densities for which the polymer has a necklace-like shape with compact beads joined b ... Full text Link to item Cite

Deterministic model of DNA gel electrophoresis Deterministic model of DNA gel electrophoresis in strong electric fields

Journal Article Electrophoresis · 1996 We present a new model for the motion of a megabase-long DNA molecule undergoing gel electrophoresis. We assume that the dynamics of large seg-ments of DNA is almost deterministic and can be described by a set of simple mechanical equations. This allows th ... Cite

Stress-induced ordering in microphase-separated multicomponent networks

Journal Article Macromolecules · 1996 Polymer blends, mixtures, or block copolymers can be cross-linked in a homogeneous state forming a multicomponent network. Upon cooling such network, the repulsion between different components may lead to a microphase separation into regions rich in each o ... Full text Cite

Elastic modulus and equilibrium swelling of polyelectrolyte gels

Journal Article Macromolecules · 1996 We present a scaling theory for the modulus G of polyelectrolyte gels as a function of strand length between cross-links, monomer concentration c, salt concentration cs, and preparation conditions (monomer concentration c0 and salt concentration cs°). The ... Full text Cite

A self-consistent mean field model of a starburst dendrimer: Dense core vs dense shell

Journal Article Macromolecules · 1996 We examine the equilibrium properties of a starburst dendrimer. A simple Flory theory is developed for the dependence of the radius of gyration of the starburst on its generation. A self-consistent mean field model is solved numerically to verify the Flory ... Full text Cite

Flory Theory of a Polyampholyte Chain

Journal Article Phys. II (France) · 1995 Cite

Scaling Theory of Polyelectrolyte Solutions

Journal Article Macromolecules · 1995 We extend and generalize the scaling picture of de Gennes et al. and Pfeuty to both unentangled and entangled regimes of intrinsically flexible polyelectrolyte solutions. In semidilute solution the electrostatic persistence length of a polyelectrolyte is a ... Cite

Reptation dynamics of a polymer melt near an attractive solid interface

Journal Article Physical Review Letters · 1995 The tracer diffusion coefficients D* of polystyrene (PS) chains near PS melt-solid interfaces have been measured by secondary ion mass spectrometry. The D* for poly(2-vinylpyridine) (PVP) and oxide (SiO) covered silicon surfaces were smaller by, respective ... Full text Cite

Network Modulus and Superelasticity

Journal Article Macromolecules · 1994 We discuss the elastic modulus G and swelling/deswelling behavior of networks as a function of their concentration φ and their preparation state. Simple scaling ideas reproduce the prediction of James and Guth for the modulus of networks swollen in a θ s ... Full text Cite

Dynamics of Stars and Linear Chains Dissolved in a Polymer Melt

Journal Article Macromolecules · 1994 We derive the mobility and the relaxation time of stars (with g arms of Z monomers each) or long linear Z-mers embedded in a homopolymer melt of linear chains of N monomers, using a dissipation approach recently proposed by de Gennes.20 For stars, we expec ... Cite

Elastic Modulus and Equilibrium Swelling of Near-Critical Gels

Journal Article Macromolecules · 1994 Scaling ideas are used to predict the modulus G0 of gels, just above the point of incipient gel formation, in the reaction bath as a function of the proximity to the gel point e. The concentration dependence of the modulus when the gel is diluted in a good ... Cite

Slippage of an entangled polymer melt on a grafted surface

Journal Article Physica A: Statistical Mechanics and its Applications · 1994 We analyse the way grafted polymers modify the slippage of an entangled polymer melt on an ideal surface. We take into account the deformation of the grafted chains in the flow (non-linear effects) and show that it alters significantly their efficiency as ... Full text Cite

Surface-Induced Lamellar Ordering in a Hexagonal Phase of Diblock Copolymers

Journal Article Macromolecules · 1994 We study theoretically the hexagonal phase of diblock copolymer melts and determine the conditions under which a region of lamellar ordering is induced near a flat surface. In the weak segregation limit we employ a Landau-Ginzburg mean-field theory to desc ... Full text Cite

Hydrodynamics of polymer solutions via two-parameter scaling

Journal Article Journal de Physique II, EDP Sciences · 1994 L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou p ... Full text Cite

Dynamics of a ring polymer in a gel

Journal Article Physical Review Letters · 1994 We present a simple scaling theory of the dynamics of a ring polymer in a gel. In the absence of excluded volume interactions, we predict that the translational diffusion coefficient D varies with the molecular weight M as D approximately M-2 and the longe ... Full text Cite

Loop statistics in adsorbed polymer solutions

Journal Article Colloids and Surfaces A: Physicochemical and Engineering Aspects · 1994 Full text Cite

Dynamics of semidilute polyelectrolyte solutions

Journal Article Physical Review Letters · 1994 We apply dynamic scaling to both unentangled and entangled semidilute polyelectrolyte solutions. The unentangled semidilute regime can span three to four decades of polymer concentration in low-salt solutions. In this range we predict such phenomena as a c ... Full text Cite

Dynamics of near-critical polymer gels

Journal Article Physical Review E · January 11, 1993 We report the viscosity and the modulus of near-critical polyester gels. Previous work has shown that these gels lie in the middle of the static crossover between mean-field and critical percolation. Above the gel point, the modulus data are well described ... Full text Cite

Dynamics of telechelic ionomers. Can polymers diffuse large distances without relaxing stress ?

Journal Article J. Phyi. /I h-ancr · 1993 L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou p ... Full text Cite

Memory Effects in Entangled Polymer Melts

Journal Article · 1993 A chain reptating through a high molecular weight polymer melt leaves a trace in the form of elastic distortions of an entanglement network. Neighboring chains can partially relax these elastic distortions by following this trace with some accuracy. Thus t ... Cite

Reinforcement of rubber by fractal aggregates

Journal Article Journal de Physique II EDP Sciences · 1993 L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou p ... Full text Cite

Power-Law-Like Stress Relaxation of Block Copolymers: Disentanglement Regimes

Journal Article Macromolecules · 1993 We consider stress relaxation in a strongly segregated lamellar mesophase, where block copolymers are in the " brush " state with junction points confined to the interface between the adjacent lamellae and blocks stretched out away from it. If the molecula ... Cite

Scaling of megabase DNA undergoing gel electrophoresis

Journal Article Journal de Physique II, EDP Sciences · 1993 L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou p ... Full text Cite

Chain Statistics in Adsorbed Polymer Solutions

Journal Article Europhysics · 1993 Cite

Slippage between a rubber and a grafted solid

Journal Article C. R. Acad. Sci. (Paris) 316, ser. II, · 1993 Cite

Giant fluctuations of crosslink positions in gels

Journal Article Physical Review Letters · 1992 A tetrafunctional network of freely jointed rigid rods in 2 dimensions is studied. At equil., the network is in a highly swollen state. Surprisingly, such a network is a crit. object with large crosslink d. fluctuations on all length scales and anomalously ... Full text Cite

Scaling Properties of Branched Polyesters. 2. Static Scaling above the Gel Point

Journal Article Macromolecules · 1992 We report experimental data on gel fraction, gel equilibrium swelling, sol intrinsic viscosity, and molecular weight distribution of the sol for a series of polyester samples above the gel point. The data are analyzed in terms of scaling relations suggeste ... Full text Cite

Unique Behavior of Dendritic Macromolecules: Intrinsic Viscosity of Polyether Dendrimers

Journal Article Macromolecules · 1992 Poly(3,5-dihydroxybenzyl alc.) dendrimers made by the convergent growth approach are characterized by size exclusion chromatog. (SEC) with coupled mol.-wt.-sensitive detection. SEC chromatograms are as narrow as chromatograms of polystyrene with mol.-wt. d ... Full text Cite

Chain Entanglement in Polymer Melts and Solutions

Journal Article Macromolecules · 1992 We consider the problem of entanglement in polymer melts and solutions with no excluded-volume interactions (esolvent). A number of simple ideas on this subject, cast in the form of scaling theories, have recently been proposedintheliterature. Atfirstglanc ... Full text Cite

Comments on fluctuations of cross‐links in gels

Journal Article Makromolekulare Chemie. Macromolecular Symposia · 1992 Localization of cross-links is an important issue in the theory of rubber elasticity. We consider freely-hinged rigid rod networks and show that in some cases they behave like critical objects: junctions fluctuate on all length scales. Such networks exhibi ... Full text Cite

Constraint Release in Polymer Melts: Tube Reorganization versus Tube Dilation

Journal Article Macromolecules · 1991 We consider the concepts of reptation and constraint release to model the dynamics of poly-disperse linear polymers. The mechanisms of constraint release at work in concentrated polymer solutions can be divided into two categories. Tube dilation occurs whe ... Full text Cite

Dynamics of Reversible Networks

Journal Article Macromolecules · 1991 We present a model for dynamics of entangled networks made up of linear chains with many temporary cross-links. At times shorter than the lifetime of a cross-link such networks behave as elastic rubbers (gels). On longer time scales the successive breaking ... Full text Cite

Universality of the Irreversibility Line

Journal Article Physical Phenomena at High Magnetic Fields · 1991 Cite

Topological Glass Transition in Entangled Flux State

Journal Article Physical Review Letters · September 3, 1990 We predict a glass transition in the recently discovered flux-fiuid state of high-T, superconductors due to topological entanglements. Two possible relaxation mechanisms are considered — single-flux-line motion with relaxation time t -exp[exp[(A/d) ][, an ... Full text Link to item Cite

Two-Parameter Scaling for Polymers in Solvents

Journal Article Macromolecules · 1990 We revive an old conjecture that a fixed number of binary contacts between chains collec-tively make up the topological constraint commonly referred to as an entanglement. This leads us to a general scaling theory for semidilute polymer solutions which inv ... Cite

’Living trees’: dynamics at a reversible classical gel point

Journal Article J. Phys.: Condens. Matter · 1990 Cite

Repton Model of Entangled Polymers

Journal Article New Trends in Physics and Physical Chemistry of Polymers · 1989 Cite

Scaling Properties of Branched Polyesters

Journal Article Macromolecules · 1989 Cite

Analysis of multiscaling structure in diffusion-limited aggregation: A kinetic renormalization-group approach

Journal Article Physical Review A · 1989 A new kinetic real-space renormalization-group (KRG) approach to diffusion-limited aggregation (DLA) is presented. It is based on the combined length- and time-scale invariance of the clusters. The probabilities relating different local configurations unde ... Full text Cite

Kinetic renormalization group approach to diffusion limited aggregation

Journal Article Physics Letters A · 1989 A new kinetic real-space renormalization group approach to the diffusion-limited aggregates is presented. The fractal dimension (Df) and the set of hierarchical dimensions D(q) are computed for the DLA cluster on the square lattice. We find Df=Ds=1.727 (Ds ... Full text Cite

Improved kinetic renormalisation group approach to diffusion-limited aggregation

Journal Article Journal of Physics A: General Physics · 1989 An improved kinetic renormalisation group approach to diffusion-limited aggregation is presented. This approach is based on the growth process itself and accounts for the dispersity in the growth probabilities. It yields the multifractal spectrum D(q) with ... Full text Cite

Self-consistent theory of polydisperse entangled polymers: Linear viscoelasticity of binary blends

Journal Article The Journal of Chemical Physics · October 15, 1988 The effects of polydispersity on the linear viscoelastic properties of concentrated polymer solutions and melts are analyzed. Existing theories for the dynamics of linear polymers, based on the idea of each polymer confined in a fixed tube, are sho ... Full text Cite

Theory of Polydispersity Effects on Polymer Rheology: Binary Distribution of Molecular Weights

Journal Article Macromolecules · 1987 Effects of polydispersity on rheological properties of entangled polymers are analyzed. A number of models of tube renewal are discussed and compared with each other and with experiments. A theory incorporating reptation, tube renewal, and fluctuations in ... Full text Cite

Discretized model of entangled-polymer dynamics

Journal Article Physical Review Letters · 1987 A discretized version of the reptation model is proposed. The tube is modeled by a one-dimensional lattice and the polymer is modeled by a cluster of walkers, called reptons, on this lattice. Each repton represents a part of the chain. Reptons are allowed ... Full text Cite

Dynamics of ring polymers in the presence of fixed obstacles

Journal Article Physical Review Letters · 1986 The configurations and dynamics of a polymer ring (R) inside a strongly crosslinked polymer gel (G) are discussed and compared to those of linear (L) and branched (B) polymers in G. R is not topologically connected to G in the sense that the contour line o ... Full text Cite

Boundary resistance and "pseudolocalization" in one-dimensional periodic systems

Journal Article Physical review B: Condensed matter and materials physics · May 15, 1983 The resistance of a one-dimensional periodic potential with large unit cell is analyzed as a function of Fermi energy and potential strength. We demonstrate that even in the allowed en-ergy regions the resistance can be nonzero due to the boundary contribu ... Full text Link to item Cite

Resistance and phase diagram of quasiperiodic systems

Journal Article Physical Review B · 1983 Full text Cite

Phase correlations in one-dimensional disordered systems

Journal Article Physical Review Letters · 1983 The correlation function of the phases of a quantum particle in a one-dimensional random potential is defined and calculated analytically and numerically. Away from eigen-states it decays exponentially with the phase correlation length equal to half of the ... Full text Cite

Order and Deterministic Chaos in Hard Disk Arrays

Journal Article Phys. Rev. B · 1982 Cite

Order in two-dimensional binary random arrays

Journal Article Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties · 1982 ISSN: 0141-8610 (Print) 1460-6992 (Online) Journal homepage: http://www.tandfonline.com/loi/tpha20 ABSTRACT Translational and orientational order in randomly packed planar arrays of hard spheres of two different sizes is investigated. For an appropriate si ... Full text Cite

Rouse mode analysis of chain relaxation in polymer nanocomposites

Journal Article Large-scale molecular dynamics simulations are used to study the internal relaxations of chains in nanoparticle (NP)/polymer composites. We examine the Rouse modes of the chains, a quantity that is closest in spirit to the self-intermediate scattering func ... Full text Cite

Effect of Short-Range Interactions on Polyelectrolyte Adsorption at Charged Surfaces

Journal Article We have studied the effect of short-range interactions on polyelectrolyte adsorption at oppositely and similarly charged surfaces. The properties of the adsorbed layer, such as polymer surface coverage, layer thickness, and surface overcharging (for adsorp ... Full text Cite

Light-Scattering Study of Diblock Copolymers in Supercritical Carbon Dioxide: CO 2 Density-Induced Micellization Transition

Journal Article The behavior of polymeric surfactant polyvinyl acetate (PVAC)-b-poly(1,1,2,2-tetrahydro-perfluorooctyl acrylate) (PTAN) in supercritical carbon dioxide (CO2) was investigated using static and dynamic light scattering. We observed three regions on the phase ... Full text Cite

Nonaffine Deformation and Elasticity of Polymer Networks

Journal Article We demonstrate that the origin of the nonlinear elasticity of polymer networks rests in their nonaffine deformations. We introduce the affine length Raff, which separates the solid-like elastic deformations on larger scales from liquid-like nonaffine defor ... Cite