Microstructure of Polyvinyl acetate)-block-Poly(methyl acrylate-co-methyl methacrylate) Block Terpolymers. 2D NMR and Thermal Study

摘要

Structural analysis of the poly(vinyl acetate)-block-poly(methyl acrylate-co-methyl methacrylate) with different MA/MMA ratios was characterized by 1D and 2D NMR. The effect of the sequence distribution, composition and stereoregularity on the unknown signals of α-CH3, backbone methylene and methin carbons were analyzed by 1D (~(13)C/DEPT-135) and 2D HSQC NMR. Furthermore, the theoretical values of triad, dyad and triad fractions of these carbons confirmed the spectral assignments. The sensitivity of the vicinal and geminal couplings of methin and methylene protons to the sequence distribution and composition were characterized using the 2D TOCSY NMR method. The influence of the sequence distribution on the theoretical glass transition temperatures of the MA/MMA copolymers was also examined using the Johnston (extended Fox) equation and experimental T_g.