SUBSTITUENT EFFECTS IN THE C-13 NMR-SPECTRA OF ARYL ETHER COPOLYMERS .5. ARYL ETHER KETONE COPOLYMERS IN ACID-SOLUTION

Complete assignments have been made for the quaternary carbon signals in the acid solution 13C n.m.r. spectra of three statistical copolymers of the aryl ether ketone unit with aryl ether ether ketone (EK/EEK), aryl ether ketone ketone (EK/EKK) and aryl ether sulphone (EK/ES). These signals are extremely sensitive to sequencing information and the spectra obtained can only be explained by considering functionality variation up to six rings removed from the observed carbon atom, C*. The transmission medium for these long range effects is the π electron system of the chain, as evidenced by the enhanced effects if the chain through which they are transmitted consists of alternating ether and ketone bridges, the most efficiently conjugated system. The effects are removed or diminished by insertion of other functionalities and there is also a correlation between the absolute chemical shift of C* and the size of splitting and amount of fine structure observed. © 1990.