(638e) Engineering “Solvation” in All-Dry Polymerization

The properties of polymer thin film synthesized by the all-dry polymerization technique were dominated by the choice of monomer, which roots in the nature of bulk polymerization. To further extend the controllability of polymer thin film, the reported work proposed the strategy of solvation engineering to control the polymer growth on the molecular level during all-dry polymerization. This report focuses on the effect of hydrogen bonding between solvent vapor and monomers, exemplified by hexafluoroisopropanol (HFIP) and 4-vinylpyridine (4VP) system. By replacing inert patch flow with solvent vapor, the deposition rate increased by 309%, and the upper bound of p4VP molecular weight was increased to over 30-fold of previously published values. Interestingly, the deposition rate linearly depends on the non-reactive solvent vapor. Such a first-order dependence was attributed to the rapid vapor-phase equilibrium of molecular complexing between monomer and solvent, supported by systematic kinetic studies and molecular dynamic simulation. The concept of solvation engineering in all-dry polymerization was further extended to acetic acid solvent and numerous methacrylates/acrylates monomers. Solvation engineering points to an exciting perspective for the CVD process development, where monomer properties like volatility and reactivity can be tuned simply by introducing vaporized solvent molecules, enabling polymers with diverse properties that were previously inaccessible.