화학공학소재연구정보센터
Applied Surface Science, Vol.450, 130-137, 2018
Salt- and thermo-responsive polyzwitterionic brush prepared via surface-initiated photoiniferter-mediated polymerization
Zwitterionic polymer brushes with strong anti-polyeletrolyte effect have shown great potential in applications of tunable friction, protein absorption/ desorption, and "killing and release" antibacterial surfaces. However, such polymer brushes are presently prepared by surface-initiated atom transfer polymerization (SI-ATRP) which is a sophisticated and time-consuming process. In this paper, a simple method, i.e. surface-initiated photoiniferter-mediated polymerization (SI-PIMP) was used to prepare poly (3( dimethyl (4-vinylbenzyl) ammonio) propyl sulfonate) (polyDVBAPS) brush on silicon wafer. It was shown that the reaction solution had a significant effect on the growth rate and surface roughness of the resulting brushes. In suitable solution (e.g. 0.53 M NaCl solution) brushes with controllable thickness and smooth surface could be obtained. Contact angle and surface friction measurement indicated that the brush prepared by SI-PIMP showed identical salt-responsive properties compared to the brushes from SI-ATRP. In addition, the thermo-responsive properties of polyDVBAPS brush was also investigated, which was further used for tuning surface friction of the brush. Due to the thermo-responsive properties, polyDVBAPS brush showed super lubrication (u similar to 10(-3)) in water and NaCl solutions with low concentrations (0.1 M and 0.53 M) when the temperature was increased to 70 degrees C, 65 degrees C and 55 degrees C respectively. Although ultralow friction could be achieved under the conditions of different temperature and salt concentration, the stability against long-term friction highly depended on the environmental condition. At 40 degrees C and in 1.0 M NaCl solution, ultralow friction was well retained up to 1500 s, while under other conditions (saturated NaCl solution of 25 degrees C and 0.53 M NaCl solution of 55 degrees C), aqueous lubrication was rapidly deteriorated. This work not only demonstrated the practicability of the SI-PIMP for the preparation of polyDVBAPS brush, but also realized the tunable surface friction of such polyzwitterionic brush under different environmental conditions, extending its applications in both academic and industrial communities. (C) 2018 Elsevier B.V. All rights reserved.