Synthesis of graft copolymers and investigation of their properties—II. Dimensions, configurations and optical properties of the macromolecules of a methyl methacrylate-styrene graft copolymer

Abstract

Dimensions, configurations, a~d optical properties of the macromolecules of the graft copolymer. The study of the structure and physical properties of graft copolymers has recently attracted the attention of a number of investigators [1-9]. This fact is explained to a considerable extent by the fact that the use of polymerization for the synthesis of graft copolymers opens up broad possibilities for the modification of the physical and mechanical properties of highly polymeric materials. On the other hand, the study of the dimensions, structure, and configurational properties of the macromolecules of a graft copolymer may also prove useful from the point of view of the investigation of the properties of molecules in general since the method of grafting permits, in principle, the production of predetermined strucgures with wide variations in the types of branching. In fact, by changing the relative lengths of the main and graft chains and the frequency of grafting, it is possible to synthesize macromolecules with a given distribution of branches--from uniformly branched [10] to the fir tree type, in which short side branches are grafted on to the long main chain. In the s tudy of molecular structures of this type, regardless of the method of their synthesis, it is first necessary to show that the polymer obtained is in fact a graft copolymer with the required proportion of grafted components in the proper spatial distribution. After careful extraction of the polymer from the reaction mixture, its average composition may, in a number of cases, be determined without difficulty both by chemical and by physical (for example, refractometric) methods. Determination of the true structure of its molecules is more difficult; for this, it is necessary to have recourse to a combination of a series of physical methods mutually supplementing one another. Light scattering and spectroscopy for example, have been used as such methods [8]. The present paper gives an analysis of the structure of the macromoleeules of a methyl methacrylate-styrene graft copolymer obtained by ionic catalytic