Synthesis of PEG‐functionalized poly(diphenylacetylene)s and their gas permeation properties

Abstract

AbstractThe polymerizations of 1‐(3‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene (1a) and 1‐(4‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene (1b) were carried out with TaCl5‐n‐Bu4Sn to give relatively high‐molecular‐weight polymers (2a and 2b) (Mn > 5 × 105). The obtained polymers were brominated by using benzoyl peroxide and N‐bromosuccinimide first, followed by substitution reaction of three types of polyethylene glycol. When diethylene glycol was used as a reagent on substitution reaction of meta‐substituted polymer, PEG‐functionalized poly(diphenylacetylene) with the highest content of oxyethylene unit [4a(2)] was obtained, and the degree of substitution was 0.60. The degrees of substitution decreased to 0.15 and 0.08 when the polyethylene glycols with higher molecular weights were used. PEG‐substitution reaction to the para‐substituted polymers was difficult to proceed, and hence the degree of substitution was 0.18 even when diethylene glycol was used. The CO2/N2 separation factor of PEG‐functionalized polymer [4a(2)] was as large as 28.8, although that of 2a was 7.41. The other PEG‐functionalized polymers also exhibited high CO2 permselectivity, and their CO2/N2 separation factors were over 20. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009