Preparation And Drug Release Of Novel Polyurethane Hydrogel

Polyurethane hydrogel is a kind of important biomedical material. It has good biological compatibility and no irritation to human tissue due to owing the advantage of both polyurethane and hydrogel, and is widely used in drug controlled release system, wound dressings and medical bandage. The hydrophilic degree of polyurethane hydrogel can influence its drug loading capacity and drug release rate; therefore, a variety of hydrophilic polyurethane products can be prepared by changing the type and of polyurethane molecular chain of hard and soft segments of polyurethane, and the effect of soft/hard segment structure on drug loading content and in-vitro drug release behavior of polyurethane hydrogel can be obtained.In this paper, a series of polyurethane(PU) prepolymers based on diphenyl-methane-diisocyanate(MDI) and polycaprolactone(PCL) were synthesized using diglycol(DEG), dimethylolpropionic acid(DMPA) and methyldiethanolamine(MDEA), respectively, as the chain-extender, then the polyurethane hydrogels were obtained from the prepolymers using benzoyl peroxide(BPO) as crosslinking agent by free radical polymerization synthesis. The effects of different types and proportions of hard segments on the polyurethane hydrogel contact angle, the degree of swelling and morphology were investigated by FTIR, static water contact angle tester and SEM. Besides, the relationship between structure and properties of the prepared polyurethane hydrogels was studied. The results showed that the polyurethane hydrogel, using DEG as chain-extender, is preferably hydrophobic, there was no micropore on its surface, The polyurethane hydrogel, using MDEA as chain-extenders, had higher hydrophilicity and micropouous structure on theirs surfaces due to their functional groups; The swelling ratio of PCL/MDI/DEG hydrogel increased and the contact angle decreased with increasing amount of DEG; however, the surface morphology was no obvious change. The swelling ratio of PCL/MDI/DEG hydrogel decreased and the contact angle increased with increasing amount of BPO.The MDI/PCL-PEG/DEG hydrogels were prepared by introduction of PEG, The effects of different types and proportions of hard and soft segments on the polyurethane hydrogel contact angle, the degree of swelling and morphology were investigated by FTIR, static water contact angle tester and SEM. The results showed that the hydrophilicity was significantly improved, the swelling degree increased, the contact angle decreases and the porosity.The drug loading and chloromycetin release behavior from the MDI/PCL/DEG and MDI/PCL-PEG/DEG hydrogel. The results indicated that the drug loading were studied. Content in the MDI/PCL/DEG was low due to the poor hydrophility, and chloromycetin released faster in the initial stage than in the latter; However the chloromycetin loading content in MDI/PCL-PEG/DEG was higher due to its good hydrophiliaty, and chloromycetin released faster in the initial stage than in the latter stage. The loading content of chloromycetin in MDI/PCL/DEG was lower at room temperature than 37.5℃, and there were not significant differences for the release behavior of chloromycetin.