Synthesis of a biobased monomer derived from castor oil and copolymerization in aqueous medium

Abstract

Vegetable oils-based polymers are promising materials with application in the industry of coatings and adhesives. Chemically-modified ricinoleic acid obtained from castor oil was used in this study to produce polymeric materials. The adopted strategy consisted in the epoxidation of the double bonds of ricinoleic acid, followed by the ring opening reaction in the presence of acrylic acid to form the acrylated ricinoleic acid (ARA). Free radical copolymerizations of ARA and methyl methacrylate (MMA) were carried out in miniemulsion, resulting in latexes stable over a long storage time. DLS measurements revealed the formation of submicron polymeric particles of different sizes strongly dependent on the fraction of the biobased monomer ARA, exhibiting diameters ranging from approximately 80nm to 150nm, as the ARA fraction was increased up to 80wt%. It was possible to prepare polymers with broad ranges of mass-average molar masses in the range from 1137kDa to 65kDa and glass transition temperatures lying in the interval from approximately 124°C–50°C by varying the concentration of the comonomer ARA. Crosslinked copolymers were obtained by increasing the proportion of ARA.