D.s.c. and n.m.r, in dilute solution and in the solid state are used to study chain conformation in poly (vinylidine cyanide-vinyl acetate) [P (VDNCN-VAc)], a highly alternating piezoelectric copolymer, in order to relate the molecular and macroscopic properties. The piezoelectricity as well as the temperature and breadth of the glass transition depends strongly on the casting solvent [dimethyl sulphoxide (DMSO) versus N,N-dimethyl formamide (DMF)] for P(VDNCN-VAc) films. Solvent effects on chain conformation are measured using through-space dipolar interactions and through-bond J couplings by high resolution n.m.r, in dilute solution via 2D and 3D n.m.r. The results show that P(VDNCN-VAc) exists in a predominantly trans conformation in both DMF and DMSO solution. No solvent effects on the 13C chemical shifts are observed in films cast from DMSO or DMF, while the molecular mobility, as measured by n.m.r, relaxation, depends strongly on the casting solvent.
Посилання на статтю:
Chain conformation in poly(vinylidene cyanide-vinyl acetate): solid state and solution 2D and 3D n.m.r, studies / Peter A. Mirau and Sharon A. Heffner // Polymer. – 1992. – Vol 33. – P. 1156-1161.