Polymer gel actuators

Irvin, D.J., S.H. Goods, and L.L. Whinnery. 2001. Direct measurement of extension and force in conductive polymer gel actuators. Chem Mater 13 1143. 

Poly(N-hydroxyalkyl-L-glutamine), 231 Poly(hydroxyethyl methacrylate) (PHRMA), 205 Poly(hydroxypropyl glutamine), 76 Poly(isopropylacrylamide) (PNIPAAm), 8, 127, 155, 160, 161, 184, 244, 259-60, 281, 284, 285, 286 Polymer aggregation, 55 Polymer films, 60 Polymer gel actuators, 258-67 Polymer gels, 48-59... 

Researchers are facing difficulties in improving the properties and response rates of chemomechanical andelectrochemomechanical systems based on polymer gels or proteins that are intended to be used as actuators in robotics. Lack of mechanical toughness and long-term durability are other problems to be solved. A basic improvement in the low efficiency... 

By coating the compliant electrodes with a thicker but softer layer of polymer gel, the gel can spread out along with the expanding fihn during actuation but bunches at points where the film compresses. If the polymers are imprinted with patterns of electrodes or shades of dots in a variety of shapes, these features can be raised or lowered to fabricate an active camouflage fabric which can change its reflectance for any defence systems and soldiers. 

After Little s proposal, many researchers have pursued such an exciting system in vain. Even metallic behavior was rarely seen in doped organic polymers, gels, and actuators. As mentioned in Sect. 3.4.4, MCso with linearly polymerized Ceo" exhibited one-dimensional (M = Rb, Cs) or three-dimensional (M = K) metallic behavior [144]. Recently a doped poly aniline was reported to exhibit a metallic temperature dependence for a crystalline polymer chemical oxidation of monomers grew crystallite polyaniline [329] early doping studies on polypyrrole (PFg) and poly(3,4-ethylene-dioxythiophene)X (X = PFg, BF4, and CF3SO3) prepared by electrooxidation at low temperatures also showed a metallic temperature dependence below 10-20 K (Scheme 16) [330, 331]. 

Non-ionic polymer gel, swollen with dielectric solvent, can be extremely deformed as is the case for non-ionic polymer plasticised with non-ionic plasticiser. Instead of the charge-injected solvent drag as a mechanism of the gel actuation, the principle is based on local asymmetrical charge distribution at the surface of the gel18. The mechanism can also be applied to non-ionic elastomers in which the motion of the polymer chain is relatively free. In spite of their many difficulties for practical actuators, polyelectrolyte gels and related materials are the most interesting electroactive polymer materials. 

Superabsorbents are superabsorbent polymers, which are loosely crosslinked hydrophilic polymers and have ionic charges in the polymers. They absorb water, swell, and retain aqueous solution above hundred times their own weight. Because of the excellent characteristics, the superabsorbents have been widely used in many applications such as disposable diapers, feminine napkins, soil additives in agricultural or horticultural applications, gel actuators, water-blocking tapes, materials for drug delivery system, absorbent pads, etc., where water absorbency or water retention is important. 

Stone HA, Stroock AD, Ajdari A (2004) Engineering flows in small devices microfluidics towards a lab-on-a-chip. Annu Rev Fluid Mech 36 381-411 Sugiura S, Sumaru K, Ohi K, Hiroki K, Takagi T, Kanamori T (2007) Photoresponsive polymer gel microvalves conbolled by local light irradiation. Sens Actuat A 140 176-184... 

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