Polymers with specific adhesion properties for surface modification: synthesis, characterization and applications

Abstract

Branched poly(ethylene imine) (PEI) with primary, secondary and tertiary amine groups in a ratio of 1:2:1 was specifically functionalized at the primary amine groups with quaternary ammonium groups and C12 alkyl chains. This reaction was performed by treatment of PEI with functional cyclic carbonates, i.e. trimethyl-(2-oxo-[1,3]dioxolan-4-ylmethyl)-ammonium iodide (1) and (2-oxo-1,3-dioxolan-4-yl)methyl dodecylcarbamate (2), under mild conditions in aprotic dipolar solvents. For determination of the reaction conditions model reactions of the functional carbonates with primary amines were performed in different solvents including water. In the presence of water side-reactions, such as hydrolysis of the ethylene carbonate ring, take place and have to be avoided. The structure of the obtained polymers was studied by means of 1H- and 13C-NMR spectroscopy, and the thermal properties were determined by means of DSC and TGA measurements. The PEI-functionalized polymers with long alkyl chains and quaternary ammonium groups are suitable for coating negatively charged surfaces by polyelectrolyte interaction. Also, the bacteriostatic properties of some amphiphilic model compounds were determined; a total inhibition of Escherichia coli by 0.01 wt% aqueous solutions was observed.