ANALYSIS OF THE C-13-NMR SPECTRA OF POLY(STYRENE OXIDE) AND OF BLOCK AND STATISTICAL COPOLYMERS OF STYRENE OXIDE AND ETHYLENE-OXIDE

Resonances in the 75.5 MHz C-13-NMR spectrum of poly(styrene oxide) (PSO) and of block and statistical copolymers of styrene oxide (SO) and ethylene oxide (EO) have been assigned with the aid of DEPT subspectral editing. Both primary and secondary hydroxyl end-groups have been identified in PSO. A simple first-order Markov model for the enchainment of SO indicates that a primary chain-end prefers to add to the CH(C6H5) head of an SO monomer but a secondary end prefers to add to the CH2 tail. In the copolymers, resonances from all possible dyads, including those with inverted addition of SO units, can be resolved. Under the conditions employed, the nuclear Overhauser enhancement of SO units is significantly less than that of EO units, and a correction may be necessary in quantitative measurements using C-13-NMR. Chemical shifts have been rationalized by a simple substituent increment scheme.