NMR EVIDENCE OF THE BLOCK STRUCTURE OF POLY(METHYL METHACRYLATE)-BLOCK-POLY(ETHYL ACRYLATE) PREPARED BY GROUP TRANSFER POLYMERIZATION

The structure of poly(methyl methacrylate)-block-poly(ethyl acrylate) prepared by group transfer polymerization was studied by H-1 and C-13 1D and 2D NMR methods including SINEPT, COSY, LR H-H-C RELAY and COLOC using model homopolymers of methyl methacrylate (MMA) and ethyl acryl ate (EA) of a length equal to that of the blocks and prepared under th e same conditions. The H-1 and C-13 Spectra of the copolymer are shown to be a superposition of the respective spectra of the homopolymers, with the exception that the copolymer lacks the terminal group present in the MMA homopolymer and the initiating group of the EA polymer. Mo reover, a new minor signal is found in the CH2 region of the copolymer which is shown to belong to the link of the blocks. The existence of a direct link between the blocks is further supported by the results o f 1D and 2D coherence transfer methods, especially those using the new ly modified DS INEPT and H-C-C RELAY pulse sequences.