Organocatalyzed β-pinene polymerization in UV light: Assessment of reaction conditions and material characterization

beta-pinene constitutes an emerging alternative for functional bio-based polymer production. Considering the diverse range of polymerization strategies, controlled organocatalyzed photopolymerization stands out as an environmentally friendly option that may be conducted without solvents and initiated by an alkyl halide under light radiation. In the present work, for the first time, the bulk photopolymerization of beta-pinene biomass under UV light was evaluated using different initiators and organocatalysts. A comprehensive structural investigation (FTIR, H-1 NMR, and C-13 NMR), a thermal scanning (TGA), and the polymer antioxidant activity were also assessed. Monomer conversion was markedly influenced by the catalyst concentration and reached a maximum value of 39.31% (8-h reaction time). The molar masses of the materials produced were low, Mn below 1200 g mol(-1). However, polymer dispersity varied from 1.06 to 1.54, indicating a substantial reaction control in most conditions tested. Kinetic evaluation of beta-pinene best-controlled polymerization, regarding the dispersity values, showed limitations in polymer chain growth, indicating the occurrence of catalyst termination, which was also confirmed by structural analysis. The synthesized polymer presented an initial degradation temperature superior to 200 degrees C and noticeable antioxidant activity compared to the monomer. Therefore, future applications of this material in polymer blends could be very beneficial to produce packagings and coatings with higher antioxidant activities.

Automated summary

β-pinene was evaluated for photopolymerization under UV light with different initiators and organocatalysts for the first time. Catalyst concentration significantly affected monomer conversion, resulting in low molar masses of the produced materials but good dispersity. The synthesized polymer showed high antioxidant activity, suggesting potential applications in producing polymer blends with enhanced antioxidant properties in the future.