COOPERATIVITY IN BACKBONE TO SIDE-CHAIN CONFORMATIONAL REARRANGEMENTSIN STEREOREGULAR PMMA

The infrared multiple absorption bands in the 1300-1100 cm(-1) range, attributed to the v(a)(C-C-O) vibration of PMMA, and the carbonyl shif t of the solid-state NMR spectra, have been analyzed in terms of confo rmational restrictions. The Av(2)/Av(1) infrared ratio, calculated fro m the absorbances of vl (at 1260-1275 cm(-1)) and vs (at 1240 cm(-1)), is found to give the ratio of the backbone conformational energy rela tive to the overall energy of the chain segment. From this ratio, it i s suggested that there are cooperative motions between the backbone an d the side chain in i-PMMA, but not in s-PMMA.