| Polyurethanes have been widely used for manufacturing medical devices because of their excellent mechanical properties(toughness, durability, and resistance to flex fatigue) and good blood compatibility. But they are not completely thromboresistant and to date have not been successful in demanding applications such as small diameter vascular grafts (< 6mm) due to adsorb protein on the materials surface and activate platelets to amplify coagulation. Recently considerable attention has been paid to biomedical polyurethanes containing phospholipid functionality, and particularly to those with the phosphorylcholine group, which is a major component of the extracellular surface of the phospholipid bilayer. It is believed that polymers containing this group provide biomembrane mimicry and should be more compatible with human body. Since the phospholipid group attached to polymer chains could not migrate, in order to prepare the polymer with phospholipid surface, a large amount of phospholipid chain extender had to employed to synthesize the polyurethanes so that the polyurethanes had high water adsorption rate in bulk, poor mechanical properties at present. In addition, the polyurethanes modified with phosphorylcholine groups on the surface couldn't decrease in protein adsorption, and the miscibility of 2-methacryloxyethyl phosphorylcholine (MPC) polymer and polyurethanes blend is relatively poor. In our studies, in order to solve these problems of phosphorylcholine polyurethanes, a novel chain extender with long fluorinated side chain phosphorylcholine and a series of fluorinated phosphorylcholine polyurethanes were designed and synthesized. The fluorinated phosphorylcholine could migrate to the surfaces or sub-surfaces, since this chain extender could change the bulk structures of the phosphorylcholine polyurethanes and the long fluorinated chain has low surface free energy. The phosphorylcholine polyurethanes were found to have high amount of phosphorylcholine on their surfaces, lower water adsorption rate and good mechanical properties. At first, Surface mobility effect of fluorinated side chain attached to hard segment on the phase separation and surface topography of polyurethanes were studied to provide the probability that fluorinated side chain phosphorylcholine could migrate to the polymer surfaces. And then, the novel chain extender with long fluorinated phosphorylcholine side chain and a series of fluorinated phosphorylcholine polyurethanes were synthesized and characterized.The main results as following:1. A unique chain extender, 3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-octyloxy)- propane-1,2-diol (PFOPDOL) was prepared from 3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8- pentadecafluoro-octyloxymethyl)-oxirane (PDFOMO) by reacting it with diluted perchloric acid. Poly(ether urethane)s and poly(carbonate urethane)s containing various amounts of the chain extender with fluorinated side chains were then synthesized using methylenebis(phenylene isocyanate) (MDI), polytetramethyleneoxide (PTMO), poly(1,6-hexyl-1,5-pentylcarbonate) diol (PHPCD), 1,4-butandiol (BDO) and PFOPDOL. The fluorinated polyurethanes with high molecular weights and good mechanical properties were obtained. Results from XPS and contact angle studies indicated that the surface of fluorinated polyurethanes were very nonpolar due to migration of fluorinated side chains to the surface. 2. For two sets of fluorinated polyurethanes, it was found that the phase separation in both bulk and surface increases in fluorinated poly(carbonate urethane)s and the phase mixing increases in fluorinated poly(ether urethane)s, with increasing amounts of fluorinated side chain. The increased degree of hydrogen bonding between hard segments and soft segments was observed by FTIR for fluorinated poly(ether urethane), which is believed to be the reason for the enhanced phase mixing, and the enhanced association of domains with long-range order (hydrogen bonding ) between hard segments was evident for fluorinated poly(carbonate urethane)s,...
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