Thermal and Chemical Properties of 3D Network Structure of Poly(Citronellyl Methacrylate-Co-EGDMA) and Poly(Geranyl Methacrylate-Co-EGDMA) Copolymers

Novel UV-cured crosslinked copolymers based on citronellyl methacrylate (CM), geranyl methacrylate (GM), and ethylene glycol dimethacrylate (EGDMA) were synthesized and characterized in terms of their chemical structure, chemical resistance, and thermal properties. ATR-FTIR analysis confirmed the involvement of both methacrylic and ethylenic double bonds in the photopolymerization process, resulting in highly crosslinked three-dimensional polymer networks. The conversion of methacrylic C=C bonds ranged from 90% ± 2% to 93% ± 1%, while the conversion of ethylenic C=C bonds ranged from 40% ± 2% to 49% ± 1%. The copolymers exhibited excellent chemical resistance, remaining insoluble and non-swollen in organic solvents as well as in acidic, alkaline, and buffer solutions. DSC analysis revealed no detectable glass transition. Thermogravimetric analysis showed that thermal stability depended on the copolymer composition, with GM-based materials exhibiting higher thermal resistance than their CM-based counterparts. TG-FTIR analysis indicated that thermal degradation was accompanied by the release of a mixture of low-molecular-mass oxygen-containing compounds, including alcohols, aldehydes, esters and/or carboxylic acids, as well as unsaturated compounds and inorganic species such as CO2, CO, and H2O. These crosslinked copolymers combine excellent chemical resistance with good thermal stability, making them promising materials for durable UV-cured coatings and advanced polymer applications.