C-13 NMR AND ESR STUDIES ON A POLYDIACETYLENE HAVING ACETYLENIC CARBONS IN THE SIDE-CHAINS

The C-13 NMR spin-lattice relaxation times and ESR spectra were measur ed for a polydiacetylene obtained by the solid-state polymerization of a tetrayne with n-C14H29 alkyl substituents (14-4A-14). Poly(14-4A-14 ) has two different side chains. One side chain contains two conjugate d acetylenic bonds directly bound to the main backbone conjugated syst em; the other is an alkyl chain. Although the unpaired electron densit y of poly(14-4A-14) measured by ESR is less than that in trans-polyace tylene, paramagnetic effects may contribute to the long C-13 relaxatio n times of unsaturated carbons, which provides insight concerning the pi-electron structure on the conjugated system.