High-Resolution Solid-State 13C NMR Studies on Molecular Motions and Solid-State Polymerization of Octatetraynes

Abstract

Abstract The effects of monomer alignment on the solid-state polymerizations of five octatetraynes and a butadiyne to produce polydiacetylenes were studied. Structural relaxations of the resulting polymers were found to occur over long time intervals. Solid-state high-resolution 13C NMR spectra were observed for six symmetrical monomers having alkyl chains (C14H29) and side chains containing either urethane or p-toluenesulfonate and the derived polydiacetylenes (PDA’s). The spin-lattice relaxation times (T1) of the PDA’s were also measured. The alignment and mobility of the monomers, which are closely related to the solid-state polymerizability and structure of the resulting polymers, are reflected in the solid-state 13C NMR spectra of the monomers. The PDA’s with urethane side chains were found to have slow structural relaxation. When the number of spacer methylenes between the acetylenic carbon and the urethane moiety is odd, a planar main-chain structure was assumed. It was found that PDA-4A’s having an odd number of spacer methylenes achieved a more homogeneous structure after long-term relaxation than a PDA-4A with an even number of spacer methylenes.