Functional polymers for layer-by-layer construction of multilayers via chemoselective immobilization

This paper reports detailed synthesis and characterization of polymers with functional groups for chemoselective immobilization. Various types of 1,4-diiodo-2,5-dialkoxybenzene monomers containing hydrophobic and hydrophilic groups with chemoselective functional group pairs were synthesized and copolymerized with 1,2-bis(4-vinylphenyl)ethane by using Heck coupling reaction. It was found that polymers with aldehyde and oxyamine pairs can easily be immobilized layer-by-layer while polymers with ketone functionalities did not afford multilayer deposition. The reproducible deposition process was monitored by UV/vis spectroscopy. Grazing angle reflection-absorption (GARA) FT-IR spectroscopic study confirmed that the multilayer assembly is driven by oxime bond formation. The experimental thickness of each layer was found to be 20 +/- 1 Angstrom by ellipsometry, somewhat shorter than that of extended side groups estimated by theoretical calculations. Tapping mode atomic force microscopy showed that the polymer multilayer with chemoselective ligation has the ability to patch up surface defects and provide smooth surface platform for further functionalization.