Structure and properties of the mesophase of syndiotactic polystyrene - III. Selective sorption of the mesophase of syndiotactic polystyrene

Syndiotactic polystyrene (sPS) has various crystalline forms such as alpha, beta, gamma, and delta forms, and a mesophase depending on the preparation method. In this study, we focused on the mesophase with the molecular cavity of sPS, which is obtained by step-wise extraction of the guest molecules from the sPS delta form. To prepare the mesophase containing different shapes and sizes of the cavity, two kinds of the sPS delta form membrane cast from either toluene or chloroform solution were first prepared and then the guest molecules were removed by a step-wise extraction method using acetone and methanol. We could succeed in the preparation of two kinds of mesophase with different shapes and sizes of the molecular cavity. Either toluene or chloroform vapor sorption to the sPS mesophase membranes was examined at 25 degreesC. Sorption analysis indicates that the mesophase with large molecular cavities can mainly sorb large molecules; on the other hand, the mesophase with small cavities can sorb only the small molecules, and is unable to sorb a large amount of large molecule because the cavity was too small to sorb the large molecules. Therefore, the sPS mesophase membrane has sorption selectivity based on the size of the molecular cavity. (C) 2003 Wiley Periodicals, Inc.