Nanocomposite poly(ethylene glycol)-poly(allylamine) thin films

Using Michael-type addition reactions we have fabricated self-assembled nanocomposite thin films consisting of alternating layers of poly(ethylene glycol) (PEG) and poly(allylamine) (PAA). This procedure has been conducted for PEGs of various chain lengths (MW 575-18,500) and in both aqueous and alcohol solvents. Increases in film thickness were quantified using ellipsometry and the introduction of various functional groups (amine, carboxyl, carbon-carbon double bond) was verified with FTIR-ERS. It was found that there was a linear increase in film thickness through three generations, excluding the first grafted PEG layer, which consistently yielded high values. This is likely due to a higher extent of reaction for the Michael-type addition of the PEG carbon-carbon double bonds with pendant amines than the initial reaction between PAA and activated mercapto-undecanoic acid (MUA). Cell and protein adhesion was examined to test biocompatibility of the modified surfaces.