Mechanochemical systems

The expansion and contraction of the polymer chain which accompanies the redox of Cu ions can also be visually confirmed by means of the mechanochemical system proposed by Kuhn161), as illustrated in Fig. 31. A film is prepared with a poly(vinylalcohol)-Cu(II) complex and is suspended with a sinker in water. The film is extended by about 20% on the reduction of Cu(II) to Cu(I) and shrinks back to its original length on the oxidation of Cu(I). The poly(vinylalcohol) chain is densely crosslinked by the extremely stable Cu(II) chelate, but is loosened when Cu ion forms the unstable Cu(I) chelate. This change is reversible as may be observed. 

Suzuki M., Nonlinear mechanochemical systems Nippon Comu Kyokaishi, 60 (1987) 702. 

Osada202 described the mechanochemical system of poly(methacrylic acid)-poly(ethylene oxide) by utilizing intermacromolecular complexation between the two component polymers (Fig. 51). The PMAA membrane is contracted by more than 90% of its original length when heated from 10 to 60 °C. When decreasing the temperature, the membrane almost completely recovers its original state. The work spent per a contraction is about 5 x 10 3 cal/g of membrane. 

Katchalsky A. Solutions of polyelectrolytes and mechanochemical systems. J Polym Sci 1952 7 393-403. 

The mechanochemical systems may be classified according to the principle of reaction ) changes in ionisation state (hydrogen-ion transfer, ion exchange, chelation) 2) redox reaction 3) steric isomerisation 4) phase transition or order-disorder transition 5) polymer-polymer association or aggregation 6) electrokinetic processes [73]. 

Mechanochemical systems based on the change of ionisation state of the system... 

We would like to prefer the term chemomechanical reaction , chemomechanical system rather than mechanochemical reaction , mechanochemical system in order to diitne more precisely... 

Suzuki M, Nonlinear mechanochemical systems , Nippon Gomu Kyokaishi, 60,702 (1987). 

The history of the creation of the first smart polymeric system dates back to the works of Kuhn and Katchalsky (88, 89). They demonstrated that collagen fibers changed dimension reversibly on transition from cyclic helices to random coils when immersed cyclically between salt solution and water. This was referred to as a mechanochemical system capable of transforming chemical energy to mechanical work. 

Osada, Y. (1987). Konbunshi. 36 353. (This system was proposed by Katchalsl et al. and was named a mechanochemical system. This terminology is more appropriately chemomechanical system or chemomechanical reaction from its concept.)... 

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