Sindee L. Simon, Dept. of Chemical Engineering, Texas Tech University, Lubbock, TX, USA.

The behavior of materials confined at the nanoscale has been of considerable interest over the past several decades, especially changes in the glass-transition temperature (T_g) and/or melting point (T_m). Less well studied are the effects of nanoconfinement on polymerization kinetics and thermodynamics. Our recent focus has been on understanding how nanoconfinement influences various classes of polymerizations, including the step-growth reactions of thermosetting resins, the free-radical reaction of various methacrylates, and the ring-opening polymerization of dicyclopentadiene. We find that changes in reaction rates under confinement can generally be explained by a competition between changes in local packing, diffusivity, and surface effects. The result is generally, but not always, an acceleration of the rate of the nanoconfined polymerization. In addition, nanoconfinement influences the chain length, PDI, and tacticity of the synthesized polymer, making confinement a potential tool for controlling synthetic outcomes. Finally, in the case of equilibrium polymerizations, nanoconfinement influences the monomer/polymer equilibrium shifting it back towards monomer, and this effect can be exploited to determine the entropy loss on confining a chain and to test scaling theories in the literature concerning confinement entropy.

Further information at talks.cam:  https://talks.cam.ac.uk/talk/index/139789