Enthalpy relaxation of photopolymerized multilayered thiol-ene films

Multilayered thiol-ene network films with two and three different components were fabricated by spin coating and photopolymerization. The distinctive glass transition temperatures of each layer component were observed at corresponding glass transition regions of each bulk sample. Sub-Tg aging of 10-, 21-, and 32-layered thiol-ene films was investigated in terms of enthalpy relaxation. Enthalpy relaxation of each layer component occurred independently and presented the characteristic time and temperature dependency. Overlapped unsymmetrical bell-shaped enthalpy relaxation distribution having peak maximum at Tg-10 degrees C of each layer component was observed, resulting in broad distribution of enthalpy relaxation over wide temperature range. In addition, enthalpy relaxation of each layer component in the multilayered thiol-ene films was significantly accelerated comparing to that of bulk thiol-ene samples. Dynamic mechanical thermal properties of multilayered thiol-ene films also showed two and three separated glass transition temperature. However, for 32-layered thiol-ene film consisting of three different layer components, glass transition and damping region are overlapped and the width is extended more than 100 degrees C. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013