Nontoxic carbene photoinitiators for sustainable biomaterials

Proposed research consists of three research thrusts: RT1- Carbene initiator utility: The structure-property relationships (SPR) will be mapped for carbene precursors initiating a range of common and sustainable resins. For the first time, the fundamental scientific investigation will explore carbene initiation of ring opening polymerization for synthesis of biodegradable polyesters and petrol-free, sustainable resins from renewable sources (e.g. itaconic acid). RT1 Objectives: Create a platform of novel, light activated carbene-initiated resins with known material properties, benchmarked against commercial competitors. RT2- Mechanism of photoinitiation: Carbene precursors with known singlet/triplet carbene ratios will be correlated with respect to the reaction mechanism of monomer degree of conversion and kinetic parameters. Active species, most efficient for polymer synthesis, will be determined as a function of carbene transient, precursor structure, and resin chemistry. RT2 Objectives: Optimize initiator efficiency with respect to carbene precursor design, reaction mechanism, resin monomer, exposure dose (joules), UVA/visible irradiation, and mol %. RT3- Minimizing toxic leachates: For the first time, the carbene photoinitiation intermediate (diazoalkane) will be investigated as a chemical absorbent of unreacted monomers after light activation. The reduction of leachates aims to improve biocompatibility of tissue contacting resins. GLP compliant, OECD biocompatibility tests will serve as an unbiased benchmark. RT3 objectives: (i) Exploit diazoalkane scavenging of unreacted monomers; (ii) Perform quantitative analysis of leachates; (iii) Biocompatibility risk assessment.