Synthesis and Characterization of Poly(limonene) by Photoinduced Controlled Radical Polymerization

Limonene is the major component of the essential oil from orange peel, with potential for polymeric production. However, due to some monomer's structural characteristics its polymerization has low yield, needing new approaches to make the process more attractive. In this paper, limonene photochemical radical polymerization at low temperature was first studied using a combination of type II photo initiators and alkyl halide initiators. Low dispersity polymers (D < 1.21) were obtained in all polymerizations. The use of 2,2,2-tribromoethanol initiator allowed to obtain higher molar mass and monomer conversion. The polymer FTIR analysis confirmed the presence of the hydroxyl group from alkyl halide. Thermal analysis (DSC and TGA) of the material indicated a T-g of approximately 10 degrees C, and the degradation of the material achieved a maximum rate in 325 degrees C, indicating good thermal stability. The obtained polymer was soft, gum-like and very malleable, making it a possible candidate of renewable additive in coatings and adhesives. Graphic