Biobased reprocessable polyisobutylene - polyurethane networks

A synthetic strategy for the preparation of novel and reprocessable biobased polyisobutylene (PIB) – polyurethane (PU) network with soybean oil (SBO) derivative was reported. For this purpose, SBO triglycerides were converted to a polyol with primary hydroxyl functionalities via UV activated thiol-ene chemistry. Optimization of grafting of hydroxyl groups was performed by varying the process parameters such as ratios of both initiator and thiol to double bond as well as the irradiation time. SBO/PIB based PU network (X-SBO/PIB-PU) was then prepared by successful integration of the SBO based polyol to PIB-PU formulation as a co-polyol. The resultant network formed a nearly optically clear film which can be swollen in good solvent. Selective cleavage of the ester bonds by acid catalyzed hydrolysis was found to be an efficient way to solubilize the network by enabling the recovery of polyurethane segments with carboxylic acid functionalities. Thermal, mechanical and microstructural characterization data confirmed that hydrolysis of the network can be conducted without disturbing the polyurethane structures with high mechanical and thermal stability. It has been suggested that hydrolyzed X-SBO/PIB-PU (H-SBO/PIB-PU) with polar functional groups can then be used as building block in the development of polymer conjugates formulated with rigid polymers and nanocomposites.