Compared to these collapsed ends, the central region is relatively swollen. It is known that preparation of the gels in a mixture of solvent/nonsolvent results in inhomogeneous structure 14, 15, 16, 17. Due to the spirobenzopyran chromophores, the illuminated ends of the gel shrink. Tetrahydrofuran (THF)/water mixture was used as a solvent for the preparation of all hydrogels. Further, drastic photo-induced proton dissociation and the recovery in the dark were repeated more than 10 times without resulting critical degradation. The acrylated spirobenzopyran is photoresponsive comonomer which is insoluble in water. The closed, colourless, hydrophobic form referred often as benzospiropyran and the open, coloured, charged merocyanine form. UV light induces the opening of the spiropyran (Sp) leading to formation of the Merocyanine (Mc). Variations of spiropyran molecules based on the core structure of 1,3,3-trimethylspiro chromene-2,2-indoline can exist in two distinctively different forms. Spirobenzopyrans are photo chromic organic compounds. The hydrogel exhibits drastic shrinking in rapid response to blue light irradiation in acidic aqueous systems, and is examined for the application of several photoresponsive actuator systems. The p K a values of the protonated chromophores in the open-ring form, which is dominant in the dark, and closed-ring form, which is dominant under irradiation, were estimated to be 6.8 and 2.6, respectively. spirobenzopyran to transform the polymer into a photo-responsivle polymer. Photoresponsive actuators composed of a hydrogel functionalized with spiropyran are described. From the systematic analysis using these spectra, the content ratios of the four forms of the chromophores were estimated for the conditions in the dark and under irradiation at various proton concentrations, revealing the quantitative aspect of drastic proton dissociation in response to the light irradiation. The molar absorption coefficient spectra of the chromophores in open-/closed-ring forms and their protonated forms were isolated respectively from the data obtained in the various conditions of proton concentration and light irradiation. Kimio Sumaru and colleagues now report on the response of thin hydrogel layers composed of a commonly used thermoresponsive polymer with an acrylated spirobenzopyran chromophore included in the. In addition, a sheet-like gel with a fast reswelling rate was operated as a micro-conveyor whose conveying direction was arbitrarily controlled with a light-irradiation.We report detailed behavior of the spirobenzopyran covalently attached to poly( N, N-dimethylacrylamide), which exhibits reversible and drastic proton dissociation in response to blue light in aqueous system. Shinbo, Probing the Dielectric Environment Surrounding Poly(N-isopropylacrylamide) in Aqueous Solution with Covalently Attached Spirobenzopyran. Two types of bending motions were observed depending on the reswelling rates of the gels a gel with a fast reswelling rate was steadily bent only during light-irradiation, whereas another gel with a slow reswelling rate showed a continuous bending motion even after the irradiation. Bending motion of a rod-like p(Sp-NIPAAm) gel was invoked by local light-irradiation because of asymmetric shrinkage of the gel. Both photo- and thermo-responsive properties of gels have been investigated and compared. Rates of reswelling from the light-induced shrunken state of the spirobenzopyran-functionalized poly( N-isopropylacrylamide) ( p(Sp-NIPAAm)) gels increased with increasing ring-opening rates of spirobenzopyrans in the gels. Poly(N-isopropylacrylamide) gels were functionalized with photo-responsive spirobenzopyran and solvent/nonsolvent mixtures were used as swelling agent to introduce network heterogeneities during the gelation process. We introduced different spirobenzopyran derivatives into poly( N-isopropylacrylamide) gels and evaluated the effects of spontaneous ring-opening rates of the spirobenzopyrans on light-responsive volume change behaviors of the gels.

Sumaru spirobenzopyran