Facile and efficient synthesis of hyperbranched polyesters based on renewable castor oil

Hyperbranched polyesters with thioether linkages were facilely prepared from methyl 10‐undecenoate, a castor oil‐derived renewable chemical. The monomer was obtained in excellent yield through thiol–ene click chemistry in the presence of catalytic amounts of photoinitiator under UV irradiation. Subsequent bulk polycondensation via a transesterification process catalyzed by Ti(OBu)4, Sb2O3 or Zn(OAc)2 gave hyperbranched polyesters with high molecular weights and unusual crystalline properties. The degree of branching in the range 0.45 − 0.54 calculated from quantitative 13C NMR spectroscopy and low inherent viscosities of 0.16 − 0.25 dL g−1 strongly confirmed the hyperbranched structures of the resultant polymers. © 2012 Society of Chemical Industry Hyperbranched polyesters based on renewable methyl 10‐undecenoate were synthesized from a monomer efficiently obtained via thiol–ene chemistry (click).