Graft copolymers molecular weight characteristics

The free radical copolymerization of a macromonomer M with a suitable comonomer A gives easy access to graft copolymers. The chief characteristic of this reaction is the large difference in molecular weights between the two species involved. Consequently, the mole fraction of macromonomer [M] in the copolymerization mixture is always low ([M] [A]). As a result, the classical... 

After separation of the pure graft copolymer, its SAN content was determined. In order to compare the characteristics of grafted and non-grafted SAN, the PB was selectively oxidized (5). The molecular weight and the acrylonitrile content of the graft could then be determined. 

The emulsifying effect of a copolymer can be characterized by determining the type of emulsion (DMF in hexane or hexane in DMF), its stability, its viscosity, and the particle size of the dispersed phase. These characteristics of oil-in-oil emulsions obtained with PS-PI block copolymers were studied as functions of solvent volume ratio, molecular weight, composition, and structure of the copolymer (5). Although Bancroft s rule was established for conventional oil-water emulsions, it appears to apply also to oil-in-oil emulsions—the continuous phase of the emulsion is preferentially formed by the solvent having the best solubility for the emulsifier (6, 7). Thus, block or graft copolymers can be prepared giving hexane/DMF, DMF/hexane, or both types of emulsions. 

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