EFFECT OF PH ON ION DYNAMICS IN COMPOSITE PPY HEPARIN FILMS/

Novel composite polypyrrole/heparin films with cation-exchange propert ies were synthesized by the electrochemical polymerization of pyrrole in the presence of heparin acting as a dopant anion at neutral pH Hepa rin was found to be permanently entrapped in the polypyrrole membrane which resulted, as expected, in the mass transport facilitated by mobi le cationic counterions. In acidic solutions, polypyrrole/heparin film s function as an anion-exchange membrane. Reversible changes from anio n dynamics to cation dynamics have been observed upon changes in the s olution pH. Information on the polymerization process and characteriza tion of charge transport and mass transport properties in these films were obtained by using the electrochemical quartz crystal microbalance technique (EQCM). (C) 1997 Academic Press.