The Preparation And Wettability Of The Responsive Polymer Thin Film

Wettability is an important property of solid surfaces that governed by both chemical composition and surface topographic structure. Stimuli-responsive surfaces can respond to the external stimuli, and have been realized by various methods, which play an important role in industrial application including chemical sensors, microfluidic devices, and so on. And, it is attracted great interests on controlling the wettability by adjusting the chemical composition or surface topographic structure with external stimuli.In this paper, we prepared pH-responsive poly(dimethyl aminoethyl methacrylate) PDMAEMA thin film and temperature-responsive poly(N-isopropylacrylamide) PNIPAm thin film both on the flat and rough silicon substrates by the surface-initiated atom transfer radical polymerization (SI-ATRP), and studied the effect and control of external stimulus to polymer thin film.A novel pH-responsive PDMAEMA thin film, whose wettability is switching between high hydrophilicity at low pH and hydrophobicity at high pH, was fabricated. Such surface effectively supplements the research on the wettability of solid surfaces based on the pH-responsive polymers, and would have applications in microfluidic devices, controllable separation systems, biotechnology, and other biomaterial applications.Solvent effect (ethanol-water solution, DMSO-water solution) on the wettability of the PNIPAm thin film was studied. The experimental results indicated that the hydrophobicity of the PNIPAm thin film at ambient temperature is the combined effect of the solvent and surface roughness. That provide theoretical basis for shaking off restrain in practice, and then extend the application scope of PNIPAm film.