Post-functionalization of fully biobased poly(limonene carbonate)s : Synthesis, characterization and coating evaluation

Fully biobased poly(limonene carbonate)s (PLCs) have been prepared by copolymerization of limonene oxide with CO2, using a ??-diiminate zinc-bis(trimethylsilyl)amido complex as the polymerization catalyst, and subsequent transcarbonation reactions using 1,5,7-triazabicyclo-[4.4.0]dec-5-ene (TBD) as the catalyst, combined with 1,10-decanediol as the transcarbonation agent. Quantitative partial post-modification of these polycarbonates was fulfilled via thiol-ene chemistry using two mercaptoalcohols with different chain lengths, viz. 2-mercaptoethanol and 6-mercaptohexanol. The thermal properties and hydroxyl values (OHVs) of the resulting hydroxyl PLCs were modulated by controlling the type and amount of incorporated thioether species. The curing kinetics of these PLCs with blocked/non-blocked multifunctional isocyanates was studied by ATR-FTIR followed by the solvent casting and curing under the optimal conditions. The good acetone resistance and high transparency and hardness of the coatings demonstrated that the fully bio-based PLCs with adequate molecular weights and OHVs are promising resins for coating applications.