Dual stimuli-responsive homopolymers: Thermo- and photo-responsive properties of coumarin-containing polymers in organic solvents

• Published in: European polymer journal Vol. 69; pp. 605 - 615
• Main Authors: Sato, Eriko, Masuda, Yuki, Kadota, Joji, Nishiyama, Takashi, Horibe, Hideo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2015
• Subjects: [2 + 2] cycloaddition; Chloroform; Coumarin; Coumarin derivatives; Cycloaddition; Dichloromethane; Distillation; Dual stimuli-responsive polymer; Isotope effect; Lower critical solution temperature; Polymers; Transmittance; [2+2] cycloaddition; Coumarin derivatives; Dual stimuli-responsive polymer; Lower critical solution temperature
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2015.05.010

[Display omitted] •Single functional unit responds to dual stimuli, temperature and light.•Lower critical solution temperature-type phase separation in the organic solvents.•Control of the lower critical solution temperature by the structure of homopolymers.•Control of thermoresponsive properties by photoreaction of the coumarin units. Thermoresponsive properties of poly(7-methacryloyloxycoumarin) (P1a) and its derivatives as homopolymers containing a photoreactive coumarin unit were systematically investigated. P1a showed a lower critical solution temperature (LCST)-type phase separation in dichloromethane, chloroform, and 1,1,2-trichloroethane. The temperature producing a 50% transmittance (Tc) of 0.1wt% P1a in distilled chloroform was 26°C, while the Tc value decreased to 21°C in deuterated chloroform i.e., the deuterium isotope effect. The Tc values in chloroform were adjustable from 28 to 57°C by the introduction of the ethyleneoxy spacer and the substitution of α-methyl group by hydrogen. While the polymers containing 4-substituted coumarins were soluble in chloroform and dichloromethane from 0°C to their boiling points. In the distilled chloroform solution, the coumarin units in P1a underwent a [2+2] cycloaddition and the transmittance at 500nm decreased from 98% to 29% at 25°C by a 180-s photoirradiation (326mJ/cm2, emission band at 365nm).