We employ an extension of the single chain in mean field simulation method to study mixtures of charged particles and uncharged polymers. We examine the effect of particle charge, polymer concentration, and particle volume fraction on the resulting particle aggregates. The structures of aggregates were characterized using particle-particle radial distribution functions and cluster size distributions. We observe that the level of aggregation between particles increases with increasing particle volume fraction and polymer concentration and decreasing particle charge. At intermediate regimes of particle volume fraction and polymer concentrations, we observe the formation of equilibrium clusters with a preferred size. We also examined the influence of manybody effects on the structure of a charged particle-polymer system. Our results indicate that the effective two-body approximation overpredicts the aggregation between particles even at dilute particle concentrations. Such effects are thought to be a consequence of the interplay between the respective manybody effects on the depletion and electrostatic interactions.

We present the results of a computational study of the interactions, phase-behavior and aggregation characteristics of charged nanoparticles (CNPs) suspended in solution of oppositely charged polyelectrolytes (PEs). We used an extension of the mean-field polymer self-consistent field theory (SCFT) model presented in our earlier work ( Macromolecules , 2014 , 47 , 6095 - 6112 ) to explicitly characterize the multibody interactions in such systems. For dilute-moderate particle volume fractions, the magnitudes of three and higher multibody interactions were seen to be weak relative to the contributions from pair interactions. On the basis of such results, we embeded the pair-interaction potentials within a thermodynamic perturbation theory approach to identify the phase behavior of such systems. The results of such a framework suggested that the gas and FCC crystal phases were thermodynamically stable, whereas the fluidlike phase was metastable in such systems. To complement the parameters studied using SCFT, we used a recently developed multibody simulation approach to study the aggregation and cluster morphologies in CNP-PE mixtures. For low particle charges, such systems mainly exhibited clusters arising from direct contact aggregation between CNPs. However, for higher particle and PE charges and low PE concentrations, large regions of PE-bridged clusters were seen to form. We present a morphological phase diagram summarizing such results.

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Controlling the morphology, domain orientation, and domain size of block copolymer (BCP) thin films is desirable for many applications in nanotechnology. These properties can be tuned during solvent annealing by varying the solvent choice and degree of swelling which affect the effective miscibility and volume fraction of the BCP domains. In this work, we demonstrate with a bulk lamellae‐forming BCP, poly(4‐trimethylsilylstyrene‐block‐D,L‐lactide) (PTMSS‐b‐PLA), that varying the composition of a mixture of solvent vapors containing cyclohexane (PTMSS‐selective) and acetone (PLA‐selective), enables formation of perpendicularly oriented lamellae with sub‐20‐nm pitch lines. The BCP domain periodicity was also observed to increase by 30%, compared to bulk, following solvent annealing. Furthermore, solvent annealing alone is shown to induce a transition from a disordered to an ordered BCP. We rationalize our observations by hypothesizing that the use of a combination of domain selective solvent mixtures serves to increase the effective repulsion between the blocks of the copolymer. We furnish results from self‐consistent field theory calculations to support the proposed mechanism. © 2013 Wiley Periodicals, Inc. J. Polym. Sci. Part B: Polym. Phys. 2014, 52, 36–45

Using single chain in mean field simulation approach, we examine the influence of fluctuation effects on the order-disorder transition (ODT) of polydisperse copolymer systems. We consider two model systems: (i) molecular weight polydisperse systems represented by AB diblock copolymer melts having monodisperse A blocks and polydisperse B blocks; and (ii) compositionally polydisperse symmetric diblock copolymer systems. In each case, we present results for the fluctuation-induced shift in the ODT from the corresponding mean-field predictions. In both models, an increase in polydispersity enhances the influence of fluctuations. Moreover, for compositionally polydisperse systems, we observe that the effects of fluctuations show similar trends in systems containing quenched and annealed representation of sequences.