Reactive polyelectrolyte multilayers onto silica particles

The two polyelectrolytes poly(vinylformamide-co-vinylamine) [P(VFA-co-VAm)] and poly(acrylic acid) (PAA) have been alternately adsorbed from aqueous solution onto silica particles with sizes in the range 15-40 μm, and a mean pore radius of 60 Å. The growth of the alternately adsorbed P(VFA-co-VAm)/PAA film has been evidenced by the zeta-potential-pH profiles as a function of the last layer adsorbed. After the multilayer formation, when P(VFA-co-VAm) was the last layer adsorbed, the hybrid materials were annealed at 120 °C to stabilize the polymer layers by a heat-induced reaction forming amide groups. IR spectra of the hybrid material, before and after thermal treatment, showed the amide linkages formation. The cross-linked hybrid materials were subsequently functionalized with S-benzyl-l-cysteine. X-ray photoelectron spectroscopy (XPS) was employed to obtain information about the amount of the amino acid S-benzyl-l-cysteine which was grafted on the free amino groups on the hybrid particle surfaces.