Isocyanate-terminated urethane prepolymer as bioadhesive base material: synthesis and characterization

The synthesis and characterization of NCO-terminated urethane prepolymer, as a base material for the process of gluing in medicine have been studied. A polyol system consisting of a polyether/polyester mixture, together with toluene diisocyanate was employed to synthesis the desired urethane-based prepolymer. The molecular structure of this prepolymer was investigated by infrared spectroscopy (FTIR), gel permeation chromatography (GPC), gas chromatography (GC) and thin layer chromatography (TLC). The obtained infrared spectrum confirmed the presence of free NCO groups bonded to the prepolymer backbone. The spreading or wetting behavior of the synthesized prepolymer was also studied by viscosity and surface tension measurement. The prepared prepolymer was found to behave as a bingham plastic from the rheological point of view. The setting and curing rate of the prepolymer was studied at ambient condition from the variation in NCO infrared peak intensity. It was found that the process of solidification of the liquid prepolymer occurs rather faster than its complete curing. Water and special catalysts were found to enhance the setting rate. The surface behavior and physico-mechanical properties of the cured thin films of the prepolymer were characterized using contact angle measurements, dynamic–mechanical and tensile tests. The cytotoxicity of the film was evaluated by in vitro cell culture experiment. Results showed a compatible cell response with no signs of toxicity.