Self-oscillating polymer brushes.

An autonomous functional surface has been designed by using self-oscillating polymers that convert the chemical energy of the Belousov-Zhabotinsky reaction into conformational changes of the polymer chains (see picture: red: hydrophobic/collapsed, green: hydrophilic/extended). Self-oscillating polymer brushes were grafted onto the inner surface of a glass capillary, and autonomous propagation of a chemical wave was observed.

Self-oscillating gel composed of thermosensitive polymer exhibiting higher LCST.

We have developed self-oscillating polymers and gels as novel biomimetic materials by utilizing an oscillating reaction, known as the Belousov-Zhabotinsky (BZ) reaction. The self-oscillating polymer gel is composed of a poly(N-isopropylacrylamide) (PNIPAAm) network in which the catalyst for the BZ reaction is covalently immobilized. Under the coexistence of the reactants, the gel undergoes spontaneous cyclic swelling-deswelling changes without any on-off switching of external stimuli. In order to induce self-oscillation while maintaining a larger amplitude at higher temperatures and around body temperature for potential applications to biomaterials, etc., here we prepared a self-oscillating gel composed of a thermosensitive N,N'-ethylmethylacrylamide (EMAAm) polymer exhibiting a higher LCST than that of the NIPAAm polymer. The self-oscillating behavior of the poly(EMAAm-co-Ru(bpy)(3)) gel was investigated by comparing against gels composed of a thermosensitive NIPAAm polymer with a lower LCST or non-thermosensitive N,N'-dimethylacrylamide (DMAAm) polymer. The design concept of self-oscillation at higher temperatures without a decrease in swelling-deswelling amplitude was demonstrated by utilizing a thermosensitive polymer exhibiting a higher LCST.