Pressure, Temperature, and Thickness Dependence of CO2-Induced Devitrification of Polymer Films

作     者：Joseph Q. Pham Stephen M. Sirard Keith P. Johnston Peter F. Green 

作者机构：Graduate Program in Materials Science and Engineering University of Texas at Austin Austin Texas 78712 USA Department of Chemical Engineering and Texas Materials Institute University of Texas at Austin Austin Texas 78712 USA 

出 版 物：《Physical Review Letters》 (Phys Rev Lett)

年 卷 期：2003年第91卷第17期

页      面：175503-175503页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

主　　题：Polymethyl methacrylates 

摘      要：The glass transition temperature is known to increase with decreasing film thickness h for sufficiently thin poly(methyl methacrylate) films supported by silicon oxide substrates. We show that this system undergoes a CO2 pressure-induced devitrification transition, Pg, which is film thickness dependent, Pg(h)=ΔPg+Pgbulk. Pgbulk is the bulk glass transition and ΔPg can be positive or negative depending on T and P. The phenomenon of retrograde vitrification, wherein the polymer exhibits a rubbery-to-glassy-to-rubbery transition upon changing temperature isobarically, is also shown to occur in this system and it is film thickness dependent.