A crystalline delta form of a syndiotactic polystyrene (sPS) membrane was prepared from a solution of sPS (1 wt %) and p-chlorotoluene (p-CT) by a solution-casting method. The mesophase (delta empty form) of sPS was obtained by the extraction of the guest solvent from the delta form of sPS by a stepwise solvent-extraction method. The sPS/p-CT mesophase membrane [p-CT (A-M)] was used for the sorption of 1 mol % p-CT for different times and for the sorption of different concentrations of p-CT, chlorobenzene (CB), p-xylene (p-X), toluene, and chloroform for 48 h. The presence of solvents in the sPS membrane was confirmed by IR analysis. A thermal study revealed that the sorption amount of 1 mol % p-CT increased with increasing immersion time, and the sorption amounts of different solvents increased with increasing solvent concentration. Differential scanning calorimetry results showed that the desorption peak temperature increased as the amount of the solvent increased in the clathrated sPS membrane. Wide-angle X-ray diffraction results showed that 20 at 8.25degrees was slightly shifted toward 8degrees, and there was no change in the peak position at 10degrees for p-CT (A-M), which was immersed in different solvents (1 mol %); however, the intensity of 2theta at 10degrees was not similar for all the samples. Among the solvents used for the sorption studies at I mol %, p-CT (A-M) could sorb more p-CT and CB than p-X, toluene, and chloroform. The solvent sorption isotherm was the Langmuir sorption mechanism. (C) 2004 Wiley Periodicals, Inc.