From Rigid to Elastic: Tailoring the Properties of Linear Poly(IBOA-co- 2EHA) Copolymers Synthesized by UV Polymerization

Abstract

This study systematically investigated poly(isobornyl acrylate (IBOA)-co-2-ethylhexylacrylate (2-EHA)) linear random copolymers synthesized via free radical photopolymerization to develop polyacrylate materials with tunable mechanical properties. A series of homopolymers and five copolymer compositions with varying IBOA content were prepared to study the relationship between structure and properties, as well as their correlation with mechanical behavior. The resulting linear polyacrylates were analyzed using multiple techniques. Structural characterization by 1H NMR and MALDI-TOF MS provided detailed information on the chemical environment, molar mass, monomer conversion rate, comonomer sequence distribution within the copolymer backbone, and end-group analysis. Size exclusion chromatography revealed molar mass distributions ranging from 105 to 106 g/mol. DSC analysis revealed composition-dependent glass transition temperatures and no crystalline melting transitions, confirming the amorphous nature of all copolymers. Tensile testing at room temperature revealed distinct mechanical properties: Poly(IBOA) (PIBOA) exhibited brittle, rigid characteristics, and Poly(2-EHA) (PEHA) displayed flexible, elastic properties. These copolymers demonstrate tunable mechanical properties as a function of comonomer composition, combining the structural rigidity of PIBOA with the flexibility of PEHA. This compositional control over mechanical behavior makes these copolymers promising candidates for applications including biomedical devices, protective coatings, adhesives, and flexible electronics, where tailored mechanical properties are essential.