CHEMICAL MODIFICATION OF CELLULOSE MEMBRANES

Cellulose membranes have contributed considerably to the development of blood-detoxification into a standard method in therapeutics, in consequence of their dialytic transport efficiency. This positive volume property is however opposed by the negative effect of complementary activation, when blood comes into contact with this membrane. This phenomenon is due to a special arrangement of the hydroxyl groups on the anhydro-glucose unit and has stimulated a variety of attempts to improve its compatibility with blood. Beside the application of admixtures, coatings or forming multiple interconnections between hydroxyl groups close to the surface, our researches are directed towards creating heterogeneous chemical surface-functions by the introduction of ionogene groups. On the basis of two-stage derivatisations and also by graft-condensation with acyl-reactive copolymers, it is possible to achieve surface-localised modifications which result in clearly reduced complementary activation, compared with the unmodified cellulose membrane. The results obtained support the hypothesis that the molecular as well as the supra-molecular structure of cellulose have a decisive influence on the compatibility of the material with blood.