HIGH-RESOLUTION SOLID-STATE C-13 NMR-STUDY OF THE INTERPOLYMER INTERACTION, MORPHOLOGY AND CHAIN DYNAMICS OF THE POLY(ACRYLIC ACID) POLY(ETHYLENE OXIDE) COMPLEX/

The interpolymer interaction, morphology and chain dynamics of the pol y(acrylic acid)/poly(ethylene oxide) (PAA/PEO) complex are examined by using C-13 CP/MAS n.m.r. methods. By analysing C-13 CP/MAS spectra of the complex we conclude that there exist three hydrogen bonding forms for the carboxyl group of PAA, namely: (1) the complex form, interpol ymer hydrogen bonding between PEO molecules; (2) the dimeric form, int rapolymer hydrogen bonding within PAA molecules; and (3) the free form , no particular form of hydrogen bonding. The morphology of the comple x is investigated by the H-1 spin-lattice relaxation time in the labor atory frame (T-1), and that in the rotating frame (T-1p). We found tha t the domain sizes of the three hydrogen bonding forms of PAA are less than a few tens of angstroms, and the PAA/PEO complex is miscible on a molecular level. Further, temperature dependence of C-13 linewidth ( T-2) is examined to study effects of complexation on the molecular mot ion of the component polymers. The temperatures at which the maximum l inewidths are observed for the main chain carbon of PEO and PAA in the PAA/PEO complex are 310 and 362 K, respectively. This indicates that the motional heterogeneity is present in spite of a single T-g for the PAA/PEO complex. Further, we discuss the structural difference betwee n the poly(methacrylic acid)/PEO complex and the PAA/PEO complex. (C) 1997 Elsevier Science Ltd.