Assembly of poly(N-isopropylacrylamide)-co-acrylic acid microgel thin films on polyelectrolyte multilayers: Effects of polyelectrolyte layer thickness, surface charge,and microgel solution pH

摘要

Temperature- and pH-sensitive poly(N-isopropylacrylamide)–nco-acrylic acid (pNIPAm-co-AAc) microgelsnwere deposited on glass substrates coated with polyelectrolytenmultilayers composed of the polycation poly(allylaminenhydrochloride) (PAH) and the polyanion polyn(sodium 4-styrenesulfonate) (PSS). The microgel densitynand structure of the resultant films were investigated as anfunction of: (1) the number of PAH/PSS layers (layernthickness); (2) the charge on the outer layer of thenpolyelectrolyte multilayer film; and (3) the pH of microgelndeposition solution. The resultant films were studied byndifferential interference contrast optical microscopy, atomicnforce microscopy, and scanning electron microscopy. It wasnfound that the coverage of the microgels on the surface wasna complex function of the pH of the deposition solution, thencharge on the outer layer of the polyelectrolyte thin filmnand the PAH/PSS layer thickness; although it appears thatnmicrogel charge plays the biggest role in determining thenresultant surface coverage.