Sindee L. Simon, Texas Tech University
Our first test of this hypothesis have focused on making measurements for methyl methacrylate polymerization under nanoconfinement. Bulk poly(methyl methacrylate) has a ceiling temperature of approximately 220 °C. Under nanoconfinement in 13 nm pores of controlled pore glass (CPG), we find that the ceiling temperature shifts to lower temperatures, as shown in the Figure, where the residual heat of reaction is plotted on the y1 axis and the conversion is plotted on the y2 axis. The shift in the ceiling temperature to lower temperatures is consistent with a decrease in the entropy of propagation under nanoconfinement. The fit to the nanoconfined data in the Figure assumes that to a first approximation, this in entropy change does not vary with temperature. Work in the coming year will focus on modeling the results to determine the scaling involved, as well as performing similar experiments for other equilibrium polymerizations.
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