Synthesis of novel poly(diphenylacetylene)s with both trimethylsilyl and alkyl groups: The effect of desilylation on gas permeability

✍ Scribed by Aiko Takeda; Toshikazu Sakaguchi; Tamotsu Hashimoto

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 385 KB
• Volume: 50
• Category: Article
• ISSN: 0032-3861
• DOI: 10.1016/j.polymer.2009.09.002

✦ Synopsis

Diphenylacetylenes having both a trimethylsilyl group and an alkyl group at para positions [Me 3 SiC 6 H 4 C^CC 6 H 4 R; R ¼ Et (1a), n-Bu (1b), t-Bu (1c), n-C 8 H 17 (1d)] and having only an alkyl group [PhC^CC 6 H 4 R; R ¼ n-Bu (1B), n-C 8 H 17 (1D)] were synthesized and then polymerized with TaCl 5 /n-Bu 4 Sn catalyst to provide the corresponding poly(diphenylacetylene)s (2a, 2b, 2c, 2d, 2B, and 2D). The formed polymers except 2c afforded tough free-standing membranes by casting from toluene solutions. Desilylation reaction of the Si-containing polymer membranes (2a, 2b, 2d) was carried out with trifluoroacetic acid, and the desilylated polymer membranes (3a, 3b, 3d) were obtained. The permeability to O 2 , N 2 , and CO 2 were determined for the obtained polymer membranes. All the desilylated membranes showed lower gas permeability than the Si-containing counterparts. To clarify the effects of the desilylation further, CO 2 diffusivity, CO 2 solubility, and fractional free volume (FFV) of the polymer membranes were investigated. The FFV and CO 2 diffusivity decreased upon desilylation, while CO 2 solubility hardly varied.