(694i) Bio-Inspired Optimization of Nanochannel Geometry and Surface Chemistry to Improve Water Permeability of Track-Etched Membrane

Authors: 
Coppens, M. O., University College London
The high water permeability of aquaporin stems from two main factors: its hourglass-shape channel structure[1], which reduces the resistance to water flow, and the narrow center inside the channel with a hydrophobic surface[2]. The selective permeation of water is further aided by the charge distribution over the channel and the resulting electrostatic interactions. Inspired by aquaporin, we optimize the nanochannel geometry and surface chemistry to improve water permeability of track-etched membranes.
Due to their straight channels, tunable channel size and shape, narrow pore size distribution and modifiable surface, track-etched membranes[3] are not only a common commercial membrane, but also a good model membrane for fundamental membrane studies and analytical separations.
Here, we tune the columnar channels on track-etched membranes to a dumbbell-shape or hourglass-shape by controlling etching time, etching temperature and etchant concentration[4]. We also modify the membrane with a dense hydrophobic layer via chemical grafting or chemical adsorption[5,6]. Both of the two optimizations on geometry and chemistry are investigated in filtration experiments to see to which degree the two factors affect the water permeability. Simulations of water flow through nanochannels are also carried out, to interpret the experimental studies, and for optimization.

REFERENCES
[1] Sui, H.; Han, B.-G.; Lee, J. K.; Walian, P.; Jap, B. K., Nature 2001, 414 (6866), 872-878.
[2] Gravelle, S.; Joly, L.; Detcheverry, F.; Ybert, C.; Cottin-Bizonne, C.; Bocquet, L., Proc. Natl. Acad. Sci. U. S. A. 2013, 110 (41), 16367-16372.
[3] Hou, X.; Zhang, H.; Jiang, L., Angew. Chem. Int. Ed. 2012, 51 (22), 5296-5307.
[4] Orelovich, O. L.; Sartowska, B. A.; Presz, A.; Apel, P. Y., J. Microsc. 2010, 237 (3), 404-406.
[5] Tian, Y.; Hou, X.; Jiang, L., J. Electroanal. Chem. 2011, 656 (1-2), 231-236.
[6] Velleman, L.; Losic, D.; Shapter, J. G., J. Membr. Sci. 2012, 411-412, 211-218.