Synthesis and properties of halogen- or methyl-containing poly(diphenylacetylene) membranes

✍ Scribed by Toshikazu Sakaguchi; Masashi Shiotsuki; Fumio Sanda; Toshio Masuda

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 185 KB
• Volume: 280
• Category: Article
• ISSN: 0376-7388
• DOI: 10.1016/j.memsci.2006.02.030

✦ Synopsis

Novel diphenylacetylenes with both trimethylsilyl groups and other substituents (R 2 C 6 H 3 C CC 6 H 4 -p-SiMe 3 , R = m,Cl, m,Cl, m,Br, m,Br, m,Me, m,Me, respectively) were polymerized with TaCl 5 -n-Bu 4 Sn to produce solvent-soluble polymers (2a-f). Most polymers (2a-e) had high molecular weight over 1 × 10 6 , and gave free-standing membranes by the solution casting method. Desilylation of these Si-containing polymer membranes was carried out with trifluoroacetic acid (TFA), which afforded solvent-insoluble desilylated polymer membranes (3a-e). According to thermogravimetric analysis (TGA), both Si-containing and desilylated polymers showed high thermal stability (T 0 ≥ 420 • C). The fractional free volume (FFV) of both Si-containing and desilylated polymer membranes (2a-d, 3a-d) were fairly large (ca. 0.27-0.32), while the FFVs of membranes (2e, 3e) were rather small (0.28 and 0.24). The oxygen permeability coefficients (P O 2 ) of 2a was as high as 5400 barrers, which is the largest among all the poly(diphenylacetylene) derivatives. Polymers 2b-d also exhibited high oxygen permeability, and their desilylated ones 3b-d retained similar high oxygen permeability. On the other hand, the P O 2 values of 2e and 3e were 1200 and 530 barrers, respectively, which are smaller than those of the halogen-containing polymers (2a-d and 3a-d).