Instabilities chemomechanical

Spontaneous Deformations in Polymer Gels Driven by Chemomechanical Instabilities... 

Boissonade etal. consider the chemoelastodynamics of responsive gels in Chapter 9. This chapter is devoted to the spontaneous generation of mechanical oscillations by a responsive gel immersed in a reactive medium away from equilibrium. Two important cases are considered. In the first case, the chemomechanical instability is mainly driven by a kinetic instabiUty leading to an oscillatory reaction. The approach is applied to the BZ reaction. The second case is a mechanical oscillatory instability that emerges from the cross-coupUng of a reaction-diffusion process and the volume or size responsiveness of the supporting material. In this case, there is no need for an oscillatory reaction. Bistable reactions, namely, the chlorite-tetrathionate (CT) and the bromate-sulfite (BS) reactions, were chosen... 

In the wake of the researches for oscillatory reactions more than a dozen pH-autoactivated reactions were shown to produce bistability when operated in a CSTR [57]. Theoretical calculations and experiments demonstrate that such systems readily give rise to spatial bistability when conducted in an OSFR. They would provide a large choice of reaction systems to test the chemomechanical instabilities theoretically described above. However, in our selection criteria, we have to take into account that many of these reactions can already exhibit kinetic oscillations over more or less wide ranges of feed parameters. Such complication can make it difficult to discriminate between kinetic and chemomechanic oscillatory instabilities. Furthermore, it has also been shown that in the case of proton-autoactivated system the natural faster diffusion of this species can lead to another source of oscillatory instability in an OSFR, the long range activation instability [58]. 

The sources of chemomechanical instabilities described above have been tested in two quite different proton-autoactivated systems the CT [63] and the BS [64] reactions. 

Yoshida, R. (2009) in Chemomechanical Instabilities in Responsive Materials, Springer NATO series A (eds P. Borckmans, P. De.Kepper, A. Khokhlov, and S. Metens), p. 39. 

Pojman, J. A. In Chemomechanical Instabilities In Flesponsive Materials (NATO Science for Reace and Security Series A Chemistry and Biology, Borckmans, P. De Kepper, P. Khokhlov, A. R. Mbtens, S., Eds. Springer Dordrecht, The Netherlands, 2009 pp 221-240. 

---