Okada Seidai, Sato Eriko
Department of Applied Chemistry and Bioengineering, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
Polymers (Basel). 2021 Jan 21;13(3):329. doi: 10.3390/polym13030329.
Coumarin-containing vinyl homopolymers, such as poly(7-methacryloyloxycoumarin) (P1a) and poly(7-(2'-methacryloyloxyethoxy)coumarin) (P1b), show a lower critical solution temperature (LCST) in chloroform, which can be controlled by the [2 + 2] photochemical cycloaddition of the coumarin moiety, and they are recognized as monofunctional dual-stimuli-responsive polymers. A single functional group of monofunctional dual-stimuli-responsive polymers responds to dual stimuli and can be introduced more uniformly and densely than those of dual-functional dual-stimuli-responsive polymers. In this study, considering a wide range of applications, organogels consisting of P1a and P1b, i.e., P1a-gel and P1b-gel, respectively, were synthesized, and their thermo- and photoresponsive behaviors in chloroform were investigated in detail. P1a-gel and P1b-gel in a swollen state (transparent) exhibited phase separation (turbid) through a temperature jump and reached a shrunken state (transparent), i.e., an equilibrium state, over time. Moreover, the equilibrium degree of swelling decreased non-linearly with increasing temperature. Furthermore, different thermoresponsive sites were photopatterned on the organogel through the photodimerization of the coumarin unit. The organogels consisting of homopolymers of coumarin-containing methacrylate exhibited unique thermo- and photoresponsivities and behaved as monofunctional dual-stimuli-responsive organogels.
含香豆素的乙烯基均聚物，如聚（7 - 甲基丙烯酰氧基香豆素）（P1a）和聚（7 - （2'-甲基丙烯酰氧基乙氧基）香豆素）（P1b），在氯仿中表现出较低临界溶液温度（LCST），其可通过香豆素部分的[2 + 2]光化学环加成来控制，并且它们被认为是单官能团双刺激响应聚合物。单官能团双刺激响应聚合物的单个官能团对双刺激作出响应，并且与双官能团双刺激响应聚合物相比，可以更均匀、更密集地引入。在本研究中，考虑到广泛的应用，分别合成了由P1a和P1b组成的有机凝胶，即P1a - 凝胶和P1b - 凝胶，并详细研究了它们在氯仿中的热响应和光响应行为。处于溶胀状态（透明）的P1a - 凝胶和P1b - 凝胶通过温度跃升表现出相分离（浑浊），并随着时间达到收缩状态（透明），即平衡状态。此外，溶胀平衡度随温度升高而非线性降低。此外，通过香豆素单元的光二聚作用，在有机凝胶上对不同的热响应位点进行了光图案化。由含香豆素的甲基丙烯酸酯均聚物组成的有机凝胶表现出独特的热响应和光响应性，并且表现为单官能团双刺激响应有机凝胶。
