Pengyu Chen

Engineering “Solvation” in All-Dry Polymerization

Organic solvents have been widely used in the synthesis of polymeric materials, although their profuse use lengthens the purification steps and generates hazardous chemical waste. While all-dry synthesis techniques like chemical vapor deposition polymerization eliminate the use of solvents and hence improve the environmental sustainability of polymer synthesis, only a narrow palette of material properties is accessible, which has been primarily limited by the available monomer chemistries. Inspired by the principles of solvent engineering in solution synthesis, we developed a novel strategy to broaden that palette via hydrogen-bonding-mediated vapor-phase complexing (namely vapor-phase solvation). We demonstrated broadened ranges of polymer chain length, of the mechanical strength, and of the variety of film surface morphology. We further extended the concept to enable an unprecedented solvation modality, i.e., interfacial solvation, that is unique to all-dry polymerization. We systematically unraveled the molecular interactions, locations of solvation, and detailed kinetics of the coupled solvation-adsorption-polymerization process via combined molecular dynamic simulations and experimental validation of a theoretical kinetic model. Generalizability of the solvation strategy was demonstrated using a variety of methacrylate and vinyl monomers. Solvation in all-dry polymerization thus offers a new degree of freedom in polymer design and synthesis with improved environmental beingness, pointing to accelerated discovery of novel polymer thin films by simply introducing active solvents in the vapor phase.