The Research Of Synthesis And Blood Compatility Of Waterborne Polyurethane/6-O-sulfochitosan Omposites

Biocompatibility, particularly blood compatibility is the mostimportant property required for biomedical materials. The improvementof blood compatibility is always an important research task forbiomaterial research and development. It is an important way to developbiomaterials by constructing special molecules onto the propermechanical material surface. Polyetherurethanes are widely used asbiomaterials due to their good biocompatibility and mechanical properties.Nevertheless, their blood compatibility is still not adequate for the moredemanding applications. The purpose of present study was to synthesis anovel nonthrombogenic biomaterial.Chitosan is a biopolymer and consists ofβ(1→4)-2-amino-2-deoxy-D-glucose repeat units. It is normally obtained by the alkalinedeacetylation of chitin, which is the second most abundant, naturallyoccurring structural material found in the shells of crustacean andcuticles of incects and also in the cell walls of some fungi andmicroorganisms. The sulfation of chitosan is the most interesting field ofits chemical modification, since chitosan has the similar structure withheparin, which is of high antithrombin activity and is popularity used inmedical field. Moreover, instead of heparin, the using of chitosanhaparinoids can reduce the risk of contamination.The main task of this dissertation is divided into three parts. In the firstpart, polyurethane emulsion with good stability was prepared, and theinfuences of n_NCO/n_OH, hydrophilic monomers, cross—linking agents and neutralization degree on the stability of emulsion and water resistance ofpaint film were discussed. PU emulsion and paint film with excellentproperties were obtained on the following conditions: n_NCO/n_OH was 1.1,the contents of DMPA was from 8 % to 10%, the contents of TMP was3%, neutralization degree was from 90 % to 100%. In the second part ofdissertation, A water-soluble chitosan sulfate was synthesized fromchitosan as raw material and characterized by IR spectrum. A sulfatedgroup at position 6 of chitosan is expected to have reaction betweenchitosan and the mix acid of sulfuric acid and chlorosulfonicacid. The optimum time is 4 hours, the reagent is a 1:2 mixture of sulfuricacid and chlorosulfonic acid, the reaction temperature is 5℃C too. Thethird part is that the WPU were respectively blended with the 6S-CS toimprove their blood compatibility. The polymeric chains of 6S-CS in theWPU/ 6S-CS composites were respectively cross-linked withglutaraldehyde to prepare semi-interpenetrated networks (semi-IPNs). Thestructure and morphologies of the composite membranes werecharacterized by infrared spectroscopy (IR) and optical polarizationmicrograph (OPM). The blood compatibility of the composite membraneswere characterized by hemolysis, recalification time and dynamic blood-clotting tests. The result showed that the composite membrane has goodblood compatibility, and it could be a good biomedical material.