Study on δ-Form Complex in Syndiotactic Polystyrene-Organic Molecules System III. Fine Structures of Complexes with Xylene Isomers by Means of High-Resolution Solid-State 13C NMR Spectroscopy

Abstract

Syndiotactic polystyrene (sPS) is known to form a clathrate compound with p-xylene and m-xylene, called δ-form complex. In this study, the structures of the sPS/p-xylene and sPS/m-xylene systems were investigated by high-resolution solid-state 13C nuclear magnetic resonance (13C NMR) and X-ray diffraction. From the Miller indices of the (0,1,0) reflection, it was confirmed that the distance between sPS helical chains in the m-xylene system was longer than that of the p-xylene system. It was concluded that the location of one methyl group of m-xylene in the sPS δ-form complex coincided with that of one methyl group of p-xylene, because the 13C NMR chemical shift and spin-lattice relaxation time of the methyl carbon of p-xylene were similar to those of one methyl carbon of m-xylene in the sPS δ-form complex. The meta substituted another methyl group of m-xylene showed a low-field chemical shift, indicating it close to the two phenyl groups of sPS chains in the δ-form complex.