(338e) Engineering Monomer Complexes in All-Dry Copolymerization

Copolymer thin films deposited via initiated Chemical Vapor Deposition (iCVD) have emerged as a promising technology for various applications, including electronic devices, biomedical devices, and separation. However, the technology has two major unmet needs: 1) the copolymerization model does not fully explain anomalous deposition kinetics, especially when strong interactions exist between monomers, and 2) the properties of copolymer films are often limited by their constituent monomers. Here, we propose a concept of monomer complexation in iCVD to broaden our understanding of deposition kinetics and achieve material properties beyond those of individual monomers. To demonstrate this concept, we utilized acidic and alkaline monomers (methacrylic acid (MA), 4-vinyl pyridine (4VP), and dimethylamine methacrylate (DMAEMA)) that form monomer complexes via hydrogen bonding or ionic bonding. We conducted a series of systematically designed experiments, along with theoretical simulations on the molecular scale, to show that the interaction strength and bond nature between monomers dominates the deposition kinetics in iCVD. Deposition rates were accelerated to 225% and 647% for MA-4VP and MA-DMAEMA pairs, respectively, and a strong tendency of alternating copolymerization was also confirmed. The concept of monomer complexation is generalizable and was demonstrated with various acidic and alkaline monomer pairs. Interestingly, the bonding nature between monomers changes film properties beyond their constituent monomers, e.g., hydrogen bonding enhanced hydrophobicity yet ionic bonding enhanced hydrophilicity. Furthermore, we showed that monomer complexation in iCVD can be used to synthesize high-performance antifouling materials and effective interfaces for loading engineered biofilms. Overall, our work provides a novel perspective on polymer design and synthesis through all-dry iCVD with improved manufacturing efficiency, and it opens up new opportunities for discovering novel polymer thin films by designing the interaction between monomers in iCVD.