Simulation study of intra- and intermicellar ordering in triblock-copolymer systems

Abstract

We report a numerical study of the structure and phase behavior of a model for a triblock-copolymer solution. The aim of this study is to investigate the nature of the dense micellar phase that can form in such systems. The simulations were performed on a lattice model for PEO ͑poly͑ethylene-oxide͒͒-PPO ͑poly͑propylene-oxide͒͒-PEO polymers. At high volume fractions, the structure factor of the amphiphile-solvent system can be mapped onto that of a monodisperse hard-sphere fluid. Yet, a low-density hard-sphere model cannot account for the properties of the dilute micellar solution. Moreover, direct inspection of the snapshots of the suspension show that these model triblock-copolymer micelles are neither hard, nor spherical, nor monodisperse.

Computational and experimental investigation of morphology in thermoplastic elastomer gels composed of AB/ABA blends in B-selective solvent

“…This distribution function measures both intra-and inter-micellar correlations and is often used to characterize micelle ordering in computational studies. 46,62,63 Fig. 11 shows the radial distribution function, g(r), of type ''A'' particles averaged from 10 parallel simulation runs.…”

Micelle formation, gelation and phase separation of amphiphilic multiblock copolymers†

“…14,15 There is a vast body of theoretical and experimental studies on diblock and triblock copolymers. 7,[16][17][18][19][20][21] Much fewer studies deal with the simulation of amphiphilic multiblock copolymers, and most of them address the questions of their structure and kinetics in dilute solutions where only intramolecular interactions play a role. 22,23 It was convincingly demonstrated that multiblock copolymers not only form intramolecular chains of micelles 24,25 but also tubular structures and intramolecular bilayers.…”

“…This is used as a definition for the critical mi-celle concentration (CMC) 46 . A similar criterion has been used for monitoring the formation of surfactant micelles 21 . In Figure 1 , at E i = −0.51, the CMC is φ = 0.01 and the distribution of core sizes becomes approximately concentrationindependent above φ = 0.02, with a stable peak in the micelle size distribution developping around 70 H monomers.…”

“…There is a vast body of theoretical and experimental studies on diblock and triblock copolymers 7,[16][17][18][19][20][21] . Much fewer studies deal with the simulation of amphiphilic multiblock copoly-mers, and most of them address the questions of their structure and kinetics in dilute solutions where only intramolecular interactions play a role 22,23 .…”

Computer simulation of aqueous block copolymer assemblies: Length scales and methods

“…By measuring the standard enthalpy of micelle formation, the authors showed that the driving force toward micellization becomes weaker when the length of the insoluble block is decreased. Wijmans et al 57 followed upon this result in their study of triblock copolymers in solution at concentrations well above the cmc to account for the experimentally observed density dependence of structural properties. In particular, they found that for ''weakly segregating'' triblock copolymers, the size of the micelles depends noticeably on the amphiphile concentration.…”