Abstract

This work explores the use of guanidine and bis-guanidine one-component organocatalysts in the synthesis of bio-based oligomers from the ROCOP (ring-opening copolymerization) reaction between olive oil-derived epoxides with maleic or phthalic anhydride. The catalysts were further evaluated in the copolymerization of methyl oleate, obtained from the saponification of olive oil triglycerides, with either maleic or phthalic anhydride. The influence of different substituents on the catalysts was systematically investigated, highlighting the role of steric and electronic effects on catalytic performance. Notably, variations in reaction conditions affected parameters such as the cis/trans incorporation ratio of maleic anhydride. Among the studied organocatalysts, G1I1 and G3I1 showed the best performance for the preparation of four bio-based polymers, poly(EOO-co-PA), poly(EOO-coMA), poly(EOOMe-co-PA), and poly(EOOMe-co-MA), achieving excellent conversions at 80 degrees C in 1-7 h. The resulting polymers were fully characterized using NMR, FT-IR, GPC, and TGA techniques. Thermal characterization by TGA/DTG and DSC revealed a strong dependence of degradation and crystallization behavior on polymer microstructure. Samples enriched in trans (maleic anhydride) units (JC-85 and JC-96) exhibited markedly higher thermal stability, with DTG maxima at 390-415 degrees C, whereas cis-rich materials (JC-90, JC-94, JC-95) degraded at significantly lower temperatures (288-381 degrees C). The enhanced resistance to thermal decomposition is attributed to the greater chain regularity and improved molecular packing promoted by trans configurations, which generate more rigid and organized domains. Complementary DFT studies provided mechanistic insights into the initiation stage and substituent effects. Furthermore, solvent-free reactions were successfully carried out, underscoring the potential of these catalysts for sustainable polymer synthesis.