Thermally stable poly(urethane-imide)s with enhanced hydrophilicity for waterproof-breathable textile coatings

摘要

Thermally stable, waterproof, hydrophilic, breathable poly(urethane-imide) (PUI) films were prepared as a potential replacement for the existing polyurethanes (PU) with a lower degree of thermal stability for waterproof breathable clothing. Hydrophilic PUI films were prepared by reacting 4,4'-diphenylmethane diisocyanate (MDI), polyethylene glycol (PEG-1500), and pyromellitic dianhydride (PMDA), with increasing hard segment (46%-61%) and compared with polyurethane films with similar PEG content. The breathability of PUI film is significantly higher than the PU film (similar to 20%). Interestingly, despite the high degree of water sorption, the PUI films exhibited higher waterproofness (similar to 85%) than the PU, which has been attributed to the presence of imide functionalities. The thermal stability of PUI was higher (T-max1 similar to 420 degrees C, T-max2 similar to 600 degrees C and char yield 21%) than the analogous PU (T-max1 similar to 360 degrees C, T-max2 similar to 420 degrees C, and char yield 6%). The waterproofness, water contact angle, and glass transition temperature are found to increase with increasing imide content, while the water sorption capacity and breathability decrease. The developed PUI coated fabric withstood hydrostatic pressure of similar to 3000 mbar, with a WVTR of 1200 g m(-2) 24 h(-1), bestowing it excellent candidature as a waterproof breathable fabric.