Self-Assembled Monolayers of a Malachite Green Derivative: Surfaces with pH- and UV-Responsive Wetting Properties
✍ Scribed by Yugui Jiang; Pengbo Wan; Mario Smet; Zhiqiang Wang; Xi Zhang
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 164 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0935-9648
No coin nor oath required. For personal study only.
✦ Synopsis
In this Communication we describe the fabrication of self-assembled monolayers of a malachite green derivative on a rough surface, resulting in wetting properties responsive to pH and UV light ranging from superhydrophobicity to superhydrophilicity with uncommon pH response and large UV response. The physicochemical properties of stimuli-responsive materials, such as surface wetting, friction, and others, can be changed depending on different external stimuli from the environment. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Stimuli-responsive materials are important in a variety of perspectives as versatile, intelligent on/off systems, for example for switchable surface wettabilities, targeted delivery of drugs and chemical agents, protein separation, [15] stimuli-modulated porous membranes for on/ off permeation and microfiltration, [16] cell culture and detachment, [17] controllable cell growth, [18] or purification of antibodies. [19] . In the field of switchable surface wettabilities, especially, a superhydrophobic/superhydrophilic switch can occur under different stimuli such as pH, [20,21] UV, [22][23][24] thermal treatment, [25] redox electrochemistry, [26] etc.
It is worth noting that such stimuli-responsive surfaces usually show a one-directional stimulus response, that is, the stimuli-responsive surfaces usually show more hydrophilic properties with increasing pH, [20,21] UV irradiation, [22][23][24] or decreasing temperature, [25] while they usually can not show more hydrophobic properties with increasing pH (Fig. 1a, curve A), UV irradiation or decreasing temperature. In fact, in the case of pH, to produce a more hydrophilic surface pretreatment of the substrate by immersion in acidic solution is usually required, [27][28][29] making such surface definitely different from the pH-responsive system described in this Communication. We were interested to see if we could realize a pH-responsive surface with completely uncommon response behavior, that is, from near-superhydrophobicity at high pH to