Diffusion limitation induced composition shift in copolymerization produces heterogeneous resin network and unpredictable mechanical performances. Specifically, low viscosity monomers tend to polymerize more at high degree of curing (DC) when monomer mobility is impeded by the vitrification of the resin. A composition-controlled photo-copolymerization was discovered by our group using urethane dimethacrylate (UDMA, a methacrylate derivative) and tri-ethylene glycol divinyl benzyl ether (TEG-DVBE, a styrene derivative) as model monomers. The equimolar composition of the feeding monomers was maintained in resin throughout the polymerization process although the viscosity of UDMA was approximately 350 times higher than that of TEG-DVBE. We found that monomers, UDMA and TEG-DVBE, formed a preorganization through hydrogen bonding. In addition, the competition between chemistry (methacrylate vs styrene) and viscosity of monomers influenced the resin composition at high DC. Consequently, composition control was achieved through rapid photo-polymerization, while composition shifted when the polymerization was slow. The mechanical properties, i.e., glass transition temperature and moduli, suggested that the composition-controlled resins formed more uniform resin network than the composition-shifted resin. In summary, the preorganization of monomers preserved their composition during rapid photo-polymerization. The composition variation in resin network leads to distinct mechanical performances. Our approach was proven successful in developing new functional materials with defined compositions and properties.<br/><br/>This research is supported by NIH U01DE023752.

Composition-controlled photo-copolymerization in a diffusion-limited environment

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.