A novel bioderived AB2-type monomer from castor oil derivative for the preparation of fully biobased hyperbranched polyesters

Designing biobased hyperbranched polyesters from vegetable oil has been attracting considerable interests from academic industrial communities. Herein, a novel fully biobased hyperbranched polyester (HBPE) was prepared by self-condensation of AB 2 -type bioderived monomer based on methyl ricinoleate (MR), a castor oil-derived renewable chemical. The reaction conditions were optimized to obtain the AB 2 -type monomer in a high conversion ratio (up to 87%). The self-condensation of AB 2 -type monomers was carried out in the presence of two kinds of transesterification catalysts (Ti(OBu) 4 versus Zn(Ac) 2 ), among which Ti(OBu) 4 was found to be more efficient one and yield higher molecular weights in the range of 5800~11,500 g/mol. The resulting HBPEs were characterized in terms of Fourier transform infrared spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, and thermogravimetric analysis. The degree of branching was calculated to be 0.33~0.39. Thermal analysis revealed that the as-prepared HBPEs were amorphous with tunable glass transition temperatures ranging from −44.8 to −24.6°C. All the prepared HBPEs exhibited good thermal stability with the maximum onset decomposition temperature ( T onset ) up to 294.6°C. These structural features and properties of resulting biobased HBPEs enabled them to act as a potential ‘greener’ additive for polymers.