Chapter 21
C O Sorption Properties of Annealed Syndiotactic Polystyrene 2
K. Tsutsui, Y . Tsujita, H . Yoshimizu, and T. Kinoshita
Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on June 23, 2016 | http://pubs.acs.org Publication Date: September 2, 1999 | doi: 10.1021/bk-1999-0733.ch021
Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
Thermal and spectral properties of annealed cast syndiotactic polystyrene (SPS) films were investigated. The sample annealed at lower temperature exhibited an ordered conformation but a lack of crystal regularity. This result indicated the presence of a mesophase. CO sorption properties of these films were also examined and dual-mode sorption parameters were obtained. In particular, the hole saturation constant for Langmuir sorption (C ') reflected the fine structure of the annealed SPS and exhibited a different annealing time dependence when annealed at different temperatures. From these results, we propose that the samples annealed at lower temperature contain many nanovoids, which form as a result of solvent desorption. 2
H
Highly syndiotactic polystyrene (SPS) crystallizes in two different conformations (TT and TTGG). One of the crystalline forms, the δ form ( T T G G conformation), is prepared by solution-casting(1,2). The δ form includes solvent molecules and is transformed into the γ form by annealing, which is accompanied by solvent desorption. This transition from the δ to the γ form has been investigated by various methodsfi,4). In this study, we investigated C0 sorption properties of SPS films, which were prepared by solution-casting and annealed at different temperatures. C 0 sorption properties probe the structural reorganization that occurs during the transition from the δ to the γ form because sorption of a penetrant molecule is sensitive to physical properties of the polymer matrix such as degree of crystallinity and fractional free volume(5). 2
2
Experimental Highly syndiotactic polystyrene (SPS) ( M = 211,000, M w
w
/ M = 3.45) was kindly n
© 1999 American Chemical Society
Freeman and Pinnau; Polymer Membranes for Gas and Vapor Separation ACS Symposium Series; American Chemical Society: Washington, DC, 1999.
287
288 supplied by Idemitsu Petrochemical Co.Ltd. Film samples cast from toluene solution were annealed at 100, 120, 140, and 170°C for various times in vacuum. The annealed SPS films have been labeled according to the following scheme : X A Y, where X is the annealing time (hours) and Y is the annealing temperature (O). Differential scanning calorimetry (DSC) thermograms in the range 25-3000 were performed using a Perkin Elmer DSC 7 at a heating rate of 20X3/min. under a nitrogen gas purge. Thermogravimetric analysis (TGA) data in the range 25-4500 were obtained using a Seiko TG/DTA220 at a heating rate of 20 C/min under a nitrogen gas purge. Wide-angle X-ray diffraction patterns in the range 5-25° 2 0 were recorded with nickel-filtered Cu Κ a radiation by a Rigaku RAD-RC diilractometcr. The scan rate was 1 ° /min. and the collection number was 5. Infrared spectra were obtained using a Jasco IR-700 type IR spectrometer operating at 1cm" resolution in the range 4000-400 cm" . The number of accumulation cycles was 1. C Q sorption isotherms at 2 5 θ were obtained by the Quartz Crystal Microbalance (QCM) method. Thin films were coated on the electrode of the Q C M by spincasting and annealed under appropriate conditions. The C 0 used in this sorption study was at least 99.9% pure and was used without further purification.
Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on June 23, 2016 | http://pubs.acs.org Publication Date: September 2, 1999 | doi: 10.1021/bk-1999-0733.ch021
