Modelling silica in aggregates of block co-polymers

Abstract

The self-assembly of block co-polymers have led to the formation of a variety of structures such as vesicles, lamellae, micelles, bi-layers and many more types. Such self-assembled materials can find applications in catalysis, engineering, drug-delivery and many other fields. A specific class of these materials is silica and block co-polymer based periodic, porous materials. In this work, we study the phase behaviour of silica, block co-polymer Poly Ethylene Oxide12- b-Poly Butyl Methacrylate10 in a solvent (Tetrahydrofuran), co-solvent (water) system. This system was selected as there are experimental evidences that this system can form certain structures with specific characteristics suited to specific applications such as in controlled delivery systems. This work builds on the phase diagram of previously reported on the same polymer, water and tetrahydrofuran (THF). While it gave valuable insights on different morphologies of the self-assembled polymer structures, no information was available on the behaviour of such systems in the presence of silica. Molecular dynamics simulations have been employed to study these systems with coarse-grained models of different molecules. A new coarse-grained model of silica has been developed under the specific conditions at which the synthesis of these materials are observed experimentally. This new model of silica was then applied to build a quaternary phase diagram of block co-polymer PEO12-b-PBMA10, THF (solvent), water (co-solvent) and silica. This phase diagram showed that by introducing silica into the polymer, water and THF system generated a phase separation over a wide range, into polymer rich phase and solvent rich phase. This separation into two phases was observed even at low concentrations of silica, with the polymer forming different structures in the polymer rich phase.

Date of Award	1 Aug 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Christopher Williams (Supervisor), Flor Siperstein (Supervisor) & Alessandro Patti (Supervisor)