Kim Junseok, Cho Yunho, Kim Soyun, Lee Jonghwi
Department of Chemical Engineering and Materials Science, Chung-Ang University, 221, Heukseok-dong, Dongjak-gu, Seoul, 156-756, Republic of Korea.
ACS Macro Lett. 2017 Oct 17;6(10):1119-1123. doi: 10.1021/acsmacrolett.7b00642. Epub 2017 Sep 27.
Hydrogels in nature seldom form a single phase, more often forming structured phases with other soft phases, allowing nature to develop responsive and adaptive strategies. Based on knowledge of how hydrogels are utilized in nature, we developed novel 3D cocontinuous composites from soft materials with extremely different properties, a hydrogel and a silicone. These were successfully prepared by infiltrating liquid polydimethylsiloxane (PDMS) into poly(-isopropylacrylamide) (PNIPAm) frameworks of aligned pores prepared by directional melt crystallization. The composites had outstanding modulus and swelling ratio compared to other mechanically strong hydrogels. More interestingly, the deswelling kinetics were dramatically accelerated (by a factor of 1000), possibly due to the aligned microchannels and the hydrophobic nature of PDMS. As a result, an actuator movement mimicking flowering could be completed in less than 20 s. This novel and versatile cocontinuous composite strategy could overcome the current limitations of soft materials.
自然界中的水凝胶很少形成单一相，更多时候是与其他软相形成结构化相，从而使自然界能够发展出响应性和适应性策略。基于对水凝胶在自然界中利用方式的了解，我们用性质极为不同的软材料——一种水凝胶和一种硅酮，开发出了新型的三维共连续复合材料。通过将液态聚二甲基硅氧烷（PDMS）渗入通过定向熔融结晶制备的具有排列孔隙的聚（N-异丙基丙烯酰胺）（PNIPAm）框架中，成功制备出了这些复合材料。与其他机械性能较强的水凝胶相比，这些复合材料具有出色的模量和溶胀率。更有趣的是，去溶胀动力学显著加快（加快了1000倍），这可能是由于排列的微通道以及PDMS的疏水性所致。结果，模仿花朵开放的致动器运动能够在不到20秒内完成。这种新颖且通用的共连续复合策略能够克服当前软材料的局限性。
