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An overview is given of our recent IR spectroscopic, optical, electrokinetic, and microscopic, studies on polyelectrolyte multilayers (PEMs), built up using the consecutive layer-by-layer technique, their interactions, and application possibilities. The influence of pH on the deposition of PEMs consisting of commercial polyelectrolyta (PELs) like poly(ethyleneimine) and poly(acrylic acid) and the adopted surface morphology of isotropic PEMs consisting of flexible PELs are reported. PEMs of azo dye/PEL are included. Those are compared with anisotropic PEMs containing stiff PELs like charged α-helical polypeptides. Furhermore, examples concerning the swelling behavior of PEMs in the presence of solutions of different low molecular salt types and the hydration of dried PEMs by the relative humidity, respectively, are given. As potent application fields, their interaction with proteins regarding both prevention of bioadhesion and protein immobilization by electrostatic interaction force are illustrated. Those studies led to principles for membrane surface modification, in order to prevent biofouling and optimize their flux and separation performance. [ABSTRACT FROM AUTHOR]

Abstract: Polycarboxybetaines – polymers containing a substituted ammonium moiety and a carboxylate group in every monomer units – show in aqueous solutions a pH-dependent intramolecular charge interactions. Here, we show that despite of this intramolecular charge effect mixing positively charge polycarboxybetaine and oppositely charged poly(maleic acid-co-propene) can yield polyelectrolyte complexes (PEC). Dynamic light scattering and viscometry has proved formation of highly swollen PEC nanoparticles with sizes in the range of 5–8nm at n−/n+ ratio from 0.6 to 1.0. Significant difference in charge densities and molecular dimensions in the solution were suggested as the main reasons for deviation from 1:1 PEC stoichiometry. [Copyright &y& Elsevier]