Modelling the Formation of Complex Morphologies via Block-copolymer Self-assembly

Amphiphilic block copolymers exhibit a very intriguing phase and aggregation behavior in aqueous solution. More specifically, they are able to self-assemble into micelles or more complex mesophases including bicontinuous... [ view full abstract ]

Amphiphilic block copolymers exhibit a very intriguing phase and aggregation behavior in aqueous solution. More specifically, they are able to self-assemble into micelles or more complex mesophases including bicontinuous phases. In particular, bicontinuous phases have recently been employed as templates for the synthesis of porous materials, incorporating micro-, meso- and macropores (1). By varying the hydrophobic/hydrophilic ratio and molecular weight of the copolymer as well as the solvent conditions, the shape and size of the aggregates can be controlled. Therefore, the success of self-assembly as a technique to synthesize new materials with specific physical, chemical and biological properties relies on the ability of recognizing the contributions that play a fundamental role in the self-organization mechanism, i.e. the driving forces (hydrophobic effect, conformational entropy and excluded volume repulsive interactions), and in this way to set the conditions for the synthesis: solvent composition, temperature and the architecture of the building blocks. In this work, we perform molecular dynamics simulations of effective coarse grained models to unveil the phase behavior of diblock copolymers that have been successfully employed in the synthesis of bicontinuous phases: PEO-b-PBMA and PEO-b-PODMA. In particular we aim to obtain the phase diagram of these copolymers in solution, which will confirm or expand the tendencies observed in experiments.

(1) B. E. McKenzie, J. F. de Visser, H. Friedrich, M. J. Wirix, P. H. Bomans, G. de With, S. J. Holder and N. A. Sommerdijk, Macromolecules 46, 9845-9848 (2013)