Aggregation of graft copolymers

Abstract

Aggregation phenomena of graft copolymers, poly(ethyl acrylate)-graft-polystyrene, are investigated by dynamic and static light scattering. The graft copolymers have well-defined structures i.e., while the molecular weights of the copolymers are almost same(about $160×10^{-3} g/mol), they have different numbers of grafted polystyrene(PS) chains, 1, 3.2, and 5.2, respectively. It was reported that the number of grafted PS chains significantly affected interfacial properties of these graft copolymers in an air/water interface $^{(1)}$. In this thesis, we investigate the aggregation phenomena of the PEA-g-PS``s in a mixed solvent(methanol/toluene), which is selectively poor for PS chains. The graft copolymer micelle is composed of collapsed PS-core and diffused PEA-corona. Our results also show that, the size and shape of graft copolymer micelles are strongly influenced by the number of PS chains per main chain. In addition, the size of the graft copolymer micelles with one grafted PS chain is a good agreement with the prediction of star-like polymer model. The structures of graft copolymer micelles are suggested from the results of dynamic and static light scattering and are further confirmed by scaling theory and space filling model. By comparing our results with the previous experiment, we conclude that the molecular weight of PEA between grafts and its ratio to that of a grafted PS chain govern the aggregation behaviors of graft copolymers.