Zwitter ionic polymer is a unique class polyelectrolyte which has not been studied systematically because of the difficulty in controlled synthesis and precise physicochemical characterization. In this study, homopolymers and polymer brushes of poly(2-methacryloyloxyethylphosphorylcholine) (PMPC) and poly[3-(N-2- methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate] (PMAPS) were prepared by ATRP. The salt-concentration dependences of the chain dimensions and swollen brush structures of PMPC and PMAPS in aqueous solutions of various ionic strengths were characterized by static light scattering, dynamic light scattering, atomic force microscopy (AFM), neutron reflectivity (NR), contact angle measurements, and macroscopic friction tests by sliding a glass ball under a load of 0.49 N. The hydrodynamic radius RH of PMPC in aqueous salt solution was independent of NaCl concentration, whereas RH of PMAPS strongly increased with the ionic strength due to the screening of attractive interaction between sulfobetaines. Similar behaviors were also observed on the PMPC and PMAPS polymer brushes on silica nano particle in water. AFM and NR measurements also showed the independence of NaCl concentration of the swollen thickness of the PMPC brush on flat silicon substrate in aqueous solution, and significant changes in the swollen thickness of the PMAPS brush in aqueous NaCl solution. PMPC and PMAPS brushes both showed oil detachment behavior in water and aqueous NaCl solutions, indicating the super hydrophilic property of both zwitter ionic polymer brushes. The PMPC brush in water had a significantly low friction coefficient (0.02�005) at a sliding velocity of 10-2 � 10-1 m/s even under a high normal pressure of 139 MPa.

Chain dimensions and surface characterization of superhydrophilic polymer brushes with zwitterion side groups prepared by ATRP

248th National Meeting (2014)

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