Using molecular dynamics simulations in combination with scaling analysis, we have studied the effects of the solvent quality and the strength of the electrostatic interactions on the conformations of spherical polyelectrolyte brushes in salt-free solutions. The spherical polyelectrolyte brush could be in one of four conformations: (1) a star-like conformation, (2) a "star of bundles" conformat...

A constitutive model is developed for the mechanical response of elastomers at finite strains. A polymer is treated as a network of linear chains linked by permanent (chemical crosslinks) and temporary (entanglements and van der Waals forces) junctions. Temporary junctions are assumed to be in two states: loose (passive) when they impose only topological constrains on available configurations o...

A multiscale modeling approach for the prediction of material stiffness of the ionic polymer Nafion is presented. Traditional rotational isomeric state theory is applied in combination with a Monte Carlo methodology to develop a simulation model of the conformation of Nafion polymer chains on a nanoscopic level from which a large number of end-to-end chain lengths are generated. The probability...

Systematic experiments were performed to investigate solvent-dependent morphology and aggregation of the semiconducting polymer film poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV), which was span-cast from nonaromatic strong polarity solvents tetrahydrofuran (THF), trichloromethane (TCM) and aromatic weak polarity solvents chlorobenzene (CB), toluene, and p-xylene. The r...

1.2 Melt Phase System Initialization. Isolated chains in the fully extended conformation were first subjected to elevated temperature (800 K) simulations using Langevin dynamics (damping parameter = 3800 fs, time step = 2 fs). Random conformations were outputted on nanosecond intervals. This protocol resulted in 60 uncorrelated chain conformation for each polymer simulated. These chains were ne...

The isolation of single polyelectrolyte chains of water-soluble poly(isocyanodipeptide)s (PICs) bearing carboxylic acid terminated side chains occurring both at surfaces and in solution was accomplished by reducing the intermolecular interactions through complexation with cations or positively charged surfactants. Scanning force microscopy and viscosity analyses revealed that this method allows...

Double stranded DNA (dsDNA) has long served as a model system for single molecule polymer dynamics. However, dsDNA is a semiflexible polymer, and the structural rigidity of the DNA double helix gives rise to local molecular properties and chain dynamics that differ from flexible chains, including synthetic organic polymers. Recently, we developed single stranded DNA (ssDNA) as a new model syste...

In sharp contrast with their amorphous counterparts, crystalline polymers provide a wealth of information on chain conformation, the packing chains in unit-cells, existence or not mirror symmetric conformations, lamellae, folds linking stems, and so forth. Three illustrations these insights are presented here: (a) orientation polymer (b) complete structural analysis alpha phase isotactic polypr...

Crystallization behaviors and related dielectric properties of semicrystalline matrix in polymer-ceramic nanocomposites have been systemically investigated by using P(VDF-TrFE) 70/30 mol.% as Ba0.5Sr0.5TiO3 nanoparticles filler. It is found that due to the presence ceramic nanofiller, there are two types crystals formed matrix: one on surface other polymer. The former favors all-trans ? phase i...

A method for the study of conjugated polyelectrolyte (CPE) photophysics in solution at the single-molecule level is described. Extended observation times of single polymer molecules are enabled by the encapsulation of the CPEs within 200-nm lipid vesicles, which are in turn immobilized on a surface. When combined with a molecular-level visualization of vesicles and CPE via cryo-transmission ele...