Well-defined monocarboxyl-terminated polystyrene with low molecular weight: A candidate for the fabrication of highly ordered microporous films and microspheres via eae static breath-figure process

Aiming at the fabrication of highly ordered microporous films, a series of well-defined monocarboxyl-terminated polystyrenes (PS-COOH) with low molecular weight (PS13K-COOH: M-n = 13 kg mo1(-1), = M-w/M-n=1.04; PS10k-COOH: M-n = 10 kg mo1(-1), M-w/M-n = 1.05; PS4.4K-COOH: Mn = 4.4 kg mol(-1), M-w/M-n = 1.05 and PS2.1k-COOH: M-n = 2.1 kg mo1(-1), M-w/M-n = 1.08) were synthesized firstly via reversible addition-fragmentation chain transfer (RAFT) polymerization using S-1-dodecyl-S'-(alpha,alpha'-dimethyl-alpha''-acetic acid) trithiocarbonate as chain transfer agent. Then, a facile static breath-figure (BF) process was employed to fabricate microporous films of PS-COOHs. The influencing factors on the morphology of such microporous films, such as relative humidity, temperature, solvent, polymer concentration and molecular weight of polymer were investigated. Highly ordered microporous film with average pore size of 1.33 pm and better regularity was fabricated through a static BF process using PS10k-COOH solution in CS2 (40 mg mL(-1)) at 22 degrees C in relative humidity of 95%. It was noteworthy that highly ordered microporous film (the average pore sizes from 0.77 mu m to 0.83 mu m) can be successfully fabricated using PS COOH with very low M-n of 2.1 kg mo1(-1) for the first time. Moreover, microsphere pattern of PS COOH with the average diameters from 0.85 mu m to 5.40 mu m was formed when replacing water with methanol as environmental vapor in the chamber for the static BF process. (C) 2014 Elsevier Ltd. All rights reserved.