Study On Preparation And Performance Of Biomedical PEU/LCP Composite Membrane

The research work in this paper is to prepare a new type polymer for the use of artificial blood vessel. Firstly, "T"style side chain liquid crystalline polymer has been synthesized by means of polyacrylamide(PAM) as flexible main chain, heparin as side chain, which is characterized by cholesteric liquid crystal through polariscope. In addition temperature range of liquid crystal has been found through DSC; Secondly, liquid crystalline polymer is blend and crosslinked with poly(ether-urethane) , which , as matrix, has been sequentially pre-treated such as endgroup-activation and grafting-modification, to manage to prepare biomedical composite with special surface structure. To clear superficial structure, SEM and critical surface tension method are used and as results properties of composite superficial microdomain including size of microdomain and distribution of phase, are determined, furthermore the size of microdomain alter with change of reaction conditions(100~1000nm). What's more, superficial analysis informs that content of heparin in composite bulk is less than that in surface layer, which may be result of self-migration of heparin ruled by lower critical free energy, hence does good to blood compatibility of PEU/LCP composite.As for biomedical materials, blood compatibility should be taken into account first. Therefore this newly prepared biomedical composite is tested by recalcification, the results are in accord with our expectation. In this paper, a new model is used to explain the cause why composite i.e. PEU/LCP composite has good blood compatibility in terms of composite surface structure. According to this model, being of dynamic protein membrane on the surface of composite when in touch with blood is looked as the main reason because this protein membrane would modify surface and as a result composite is not or less going to be recognized by blood system as a foreign. Mechanical properties are also important for biomedical macro-materials, especially biomedical frame, therefore composite is tested through stress-strain tests and creep mechanics test. The results show that PEU/LCP composite, compared with pure PEU membrane, has lower stress-strain stretch strength, and then is apt to be used for biomedical polymer.Besides some merits mentioned above, this reaction conditions adopted to prepare PEU/LCP composite is moderate and at the same time this preparation technology are simple. However there still are shortcomings in this paper such as not-quantum self-migration of heparin from composite bulk to surface layer and some shortages in experiments contents, whose solution would contribute to accurate molecular design of biomedical composite and explain of anticoagulant theory.