Smart membranes

Otero, T. R Martinez, J. G. Arias-Pardilla, J. Biomimetic electrochemistry from conducting polymers. A review artificial muscles, smart membranes, smart drug delivery and computer/neuron interfaces. Electrochim. Acta 2012, 84, 112-128. 

Membrane structures stimuli-responsive hydrogel membrane (a), membrane with stimuli-responsive grafted brushes (b), stimuli-responsive membrane with porous substrate (c) and responsive gates (d). Source Reproduced from Chu, Xie and Ju (2011). Stimuli-responsive membranes Smart tools for controllable mass-transfer and separation processes. Chinese Journal of Chemical Engineering, 19,891-903. Copyright (2012), with permission from Elsevier.) (Chu eta ., 2011). 

Chu, L. Y., Xie, R. and Ju, X. J. (2011). Stimuli-responsive membranes Smart tools for controllable mass-transfer and separation processes. Chinese Journal of Chemical Engineering, 19,891-903. 

Minko S (2010) Stimuli-responsive thin hydrogel films and membranes. Smart polymer systems 2010, 1st Inlemational Crarfiaenee, Atlanta, GA, May 5-6, 2010... 

The presence of polymer, solvent, and ionic components in conducting polymers reminds one of the composition of the materials chosen by nature to produce muscles, neurons, and skin in living creatures. We will describe here some devices ready for commercial applications, such as artificial muscles, smart windows, or smart membranes other industrial products such as polymeric batteries or smart mirrors and processes and devices under development, such as biocompatible nervous system interfaces, smart membranes, and electron-ion transducers, all of them based on the electrochemical behavior of electrodes that are three dimensional at the molecular level. During the discussion we will emphasize the analogies between these electrochemical systems and analogous biological systems. Our aim is to introduce an electrochemistry for conducting polymers, and by extension, for any electrodic process where the structure of the electrode is taken into account. 

Desalination of sea water, or purification to eliminate dangerous ionic contaminants from industrial waste water involves important technological, scientific and financial risks. Most of them are related to the development of cheaper smart membranes that can mimic biological membranes. 

S. R. Narayanan, A. Kindler, B. Jeffries-Nakamura, W. Chun, H. Frank, M. Smart, S. Surampudi, and G. Halpert, in Proc. of the First International Symposium on Proton Conducting Membrane Fuel Cells, Ed. by S. Gottesfield, G. Halpert, and A. R. Landgrebe, The Electrochemical Society, Pennington, NJ, PV 95-23, 1995, pp. 261-266. 

Solid mixed ionic-electronic conductors (MIECs) exhibit both ionic and electronic (electron-hole) conductivity. Naturally, in any material there are in principle nonzero electronic and ionic conductivities (a i, a,). It is customary to limit the use of the term MIEC to those materials in which a, and 0, 1 do not differ by more than two orders of magnitude. It is also customary to use the term MIEC if a, and Ogi are not too low (o, a i 10 S/cm). Obviously, there are no strict rules. There are processes where the minority carriers play an important role despite the fact that 0,70 1 exceeds those limits and a, aj,i< 10 S/cm. In MIECs, ion transport normally occurs via interstitial sites or by hopping into a vacant site or a more complex combination based on interstitial and vacant sites, and electronic (electron/hole) conductivity occurs via delocalized states in the conduction/valence band or via localized states by a thermally assisted hopping mechanism. With respect to their properties, MIECs have found wide applications in solid oxide fuel cells, batteries, smart windows, selective membranes, sensors, catalysis, and so on. 

Smart chemical reaction engineering can also solve the separation problem. Multifunctional reactors based on distillation or membrane separation wil gain importance in the future (see also Chapter 6). 

Uittenbogaard, A, Everson, WV, Matveev, SV, and Smart, EJ, 2002. Cholesteryl ester is transported from caveolae to internal membranes as part of a caveolin-annexin II lipid-protein complex. J Biol Chem 277,4925—4-931. 

The combined features of structural adaptation in a specific hybrid nanospace and of a dynamic supramolecular selection process make the dynamic-site membranes, presented in the third part, of general interest for the development of a specific approach toward nanomembranes of increasing structural selectivity. From the conceptual point of view these membranes express a synergistic adaptative behavior the addition of the most suitable alkali ion drives a constitutional evolution of the membrane toward the selection and amplification of a specific transport crown-ether superstructure in the presence of the solute that promoted its generation in the first place. It embodies a constitutional selfreorganization (self-adaptation) of the membrane configuration producing an adaptative response in the presence of its solute. This is the first example of dynamic smart membranes where a solute induces the preparation of its own selective membrane. 

The understanding of bio- and chemo-catalytic functionalities, their integration in recognizing materials (doped materials, membranes, tubes, conductive materials, biomarker detection, etc.) and the development of smart composite materials (e.g., bio-polymer-metal) are all necessary elements to reach above objectives. It is thus necessary to create the conditions to realize a cross-fertilization between scientific areas such as catalysis, membrane technology, biotech materials, porous solids, nanocomposites, etc., which so far have had limited interaction. Synergic interactions are the key factor to realizing the advanced nanoengineered devices cited above. 

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