No abstract

The characterization of ABA-type triblock copolymer films derived from polyimide (PI) macroinitiator and poly(methyl methacrylate) (PMMA) synthesized by atom transfer radical polymerization was investigated by focusing on different block lengths of PMMA. The hydrophobic property tends to increase with increasing PMMA content in the triblock copolymers, while the PMMA blocks enhance the charge transfer interaction between the PI segments. The water vapor sorption measurement of triblock copolymers was determined at 35 • C. The water vapor solubility of triblock copolymers tends to decrease with increasing PMMA content. In addition, linear correlations were observed between the solubility and polymer-free volume and polymer molecular polarity in triblock copolymers as well as in other conventional polymer families. According to Zimm−Lundberg analysis, the PMMA block segments in the triblock copolymers accelerate water vapor clustering due to the high mobility of PMMA. The mobility of PMMA block segments strongly affected not only physical properties but also the water vapor solubility of the triblock copolymers. The ABA triblock copolymerization composed of PI and PMMA is one of the effective ways to improve the hydrophobic property.

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. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43795.