Solid-state carbon-13 NMR study of thermotropic polybibenzoates. 1. Poly(heptamethylene, p,p'-bibenzoate) and poly[oxybis(trimethylene) p,p'-bibenzoate]

Poly(heptamethylene p,p'-bibenzoate) (P7MB) and poly(oxybis[trimethylene] p,p'-bibenzoate) (PDTMB) with different thermal histories were studied at room temperature. These polymers both form smectic liquid crystalline (LC) phases as well as conventional crystalline (CR) phases. Signals from the CR regions were separated from those of the noncrystalline (NC) regions, and some information about inequivalence within the CR unit cells was obtained. A NMR comparison of quenched versus annealed PDTMB soght to contrast the LC behavior in the quenched sample versus the NC behavior in the annealed sample