Phototransparency and water vapor sorption properties of ABA-type triblock copolymers derived from 6FDA-TeMPD and poly(2-methyl-2-adamantylmethacrylate)

The phototransparency and water vapor sorption properties of ABA-type triblock copolymer membranes derived from 4,4-(hexafluoroisopropylidene) diphthalic anhydride-2,3,5,6-tetramethyl-1,4-phenylenediamine (PI) and poly(2-methyl-2-adamantylmethacrylate) (PMAdMA) were investigated, with focus on the effect of the adamantane component. The phototransparency of PMAdMA-block-PI-block-PMAdMA [Block(PI/PMAdMA)] was about 10-20% higher than that of poly(methyl methacrylate)-block-PI-block-Poly(methylmethacrylate) [Block(PI/PMMA)] because the high symmetric structure of adamantane inhibited photoabsorbance. The water vapor solubility of Block(PI/PMAdMA) decreased with increased PMAdMA because the PMAdMA had a hydrophobic property. Interestingly, in all relative-pressure regions, Block(PI/PMAdMA) with the least PMAdMA content showed a higher solubility coefficient than PI because the high mobility of PMAdMA in Block(PI/PMAdMA) resulted in additional sorption sites in the PI segment. A comparison of Block(PI/PMAdMA) with Block(PI/PMMA) in terms of relative pressure at the beginning of clustering further revealed that cluster formation in Block(PI/PMAdMA) was inhibited compared with Block(PI/PMMA) because bulky structure of adamantane restricted the mobility of the polymer main chain. (C) 2016 Wiley Periodicals, Inc.