Biodegradable hydrophobic polyurethane / hydrophilic poly(ethylene glycol)diacrylate IPNs for enhanced blood compatibility

Abstract

In this dissertation, we synthesized biodegradable hydrophobic polyurethane(PU) / hydrophiphilic poly(ethylene glycol)diacrylate (PEGDA) IPNs having micro-separated structure to overcome the problems caused in the long-term clinical use. Polyurethane was modified using biocompatible and biodegradable PCL diol and the hydroxyl group of PEG was substituted to crosslinkable acrylate group. PU/PEGDA IPNs were synthesized changing the molecular weight of PEGDA to investigate the effect of crosslinking density on morphology, bulk and surface hydrophilicity and blood compatibility was investigated. From the DSC results, it was shown that all PU/PEGDA IPNs had one broad Tg between the Tgs of two pure components. All PU/PEGDA IPNs had micro-separated structure in which the PEGDA-rich phase formed the continuous matrix and the PU-rich phase formed the dispersed domain, since the reaction rate of PEGDA was faster than that of PU. The domain size of PU/PEGDA IPNs decreased as decreasing the molecular weight of PEGDA, which indicated an increase in the intermixing between the PU-rich phase and the PS-rich phase. The micro-separated structure was stable in water and the domain size was almost the same as air. The equilibrium-swelling ratio in water decreased with decreasing the molecular weight of PEGDA due to the increased crosslinking density. The interfacial energy of PEGDA homo networks and PU/PEGDA IPNs was decreased with increasing the molecular weight of PEGDA. The degradation of PU/PEGDA IPNs occurs rapidly after 16 weeks, whereas PEGDA networks and PU networks degrade little after 30 weeks. The weight loss of PU/PEGDA 6k IPNs is highest in all IPNs due to the highest swelling ratio. The amount of adhered platelet of all PU/PEGDA IPNs was lower than that of PU homo network due to the micro-separated strucutre of IPN. In PU/PEGDA 2k IPN, relatively smaller amount of platelet was adhered due to the smallest hydrophobic domain size of the surface morphology in all PU...