Synthesis and characterization of degraded gelatin grafted poly(ɛ-caprolactone) copolymers

Abstract

Hydrophilic degraded gelatin was modified with hydrophobic poly(ɛ-caprolactone) (PCL) via a chemical grafting route. Firstly, PCL with one hydroxyl end group was prepared by the ring-opening polymerization of ɛ-caprolactone (ɛ-CL) with tin (II) 2-ethylhexanoate as catalyst and n-butyl alcohol as initiator. Secondly, the PCL reacted with isophorone diisocyanate (IPDI) to prepare PCL with isocyanate functional group (PCL-NCO). Hydroxylamine was used to degrade gelatin by the cleavage between asparagine and glycine residues of gelatin. PCL-NCO reacted with the hydroxyl/amino groups of degraded gelatin in a homogeneous system and yielded the PCL modified gelatin copolymers. The gelatin grafted PCL copolymers were measured by means of XRD, FTIR, DSC and 1H NMR. The results confirmed the conjugation of PCL onto gelatin chains. The PCL modified gelatin can be used as biomaterials owing to their biocompatibility and biodegradation.