Phase Structure And Photoinduced-Deformable Behavior Of Liquid Crystalline Elastomer Cross-linked Via Hydrogen Bond

Photoinduced-deformable liquid crystal elastomer(LCEs) is a kind of promising material for actuators, artificial muscles, microfluidic systems, however, as for the LCEs there are some local defects and internal microscopic defects in the application process, which would weaken its mechanical and functional performance. In this paper, we have used the random free radical polymerization method to build a series of new photoinduced-deformable liquid crystal elastomer which based on the hydrogen bond as the crosslinking agent, the glass transition temperature of the elastomer was adjusted via copolymerizing butyl acrylate. At the same time, two types of azobenzene liquid crystal elastomer based on the acroleic acid and meth acrylic acid as the main chain was synthesized to compare the influence of the main chain vary.1. The homopolymer PAAZo(S1) and copolymer liquid crystal elastomer PAAZo-co-PBA-co-HUUx(Sn, n = 2, 3, 4, 5) has been synthesized successfully, GPC and 1 HNMR results has indicated the content of different components and relative molecular weight. DSC, POM, 1D WAXD experiments showed that the cross-linking agent and butyl acrylate could decrease the glass transition temperature(Tg)of the elastomers, and impeded the development of the liquid crystal, the homopolymer PAAZo(S1) exhibited smectic B phase structure at room temperature, and the crosslinking agent and butyl acrylate undermined the development of liquid crystal rheological tests showed the series LCEs exhibited elastomeric properties at room temperature, and the multiple relaxation peaks appeared on the Loss Factor – Temperature curve were represented the temperature of the glass transition and hydrogen elastomer gradual dissociation, respectively. In addition, the experiment of flexibility test showed the excellent performance, moreover, photoinduced test showed the elastomer has certain light deformation.2. The homopolymer PMAZo(P1) and copolymer liquid crystal elastomer PMAZo-co-PBA-co-HUUx(Pn, n = 2, 3, 4, 5) with methacrylic acid as the main chain has been synthesized successfully, GPC and 1 HNMR results has indicate the content of different components and relative molecular weight. DSC, POM, 1D WAXD, 2D WAXD were used to explore the phase behavior and phase structure. The results showed that the cross-linking agent and butyl acrylate could decrease the Tg, the liquid crystal texture and the domain size had been greatlly impacted by the cross-linking agent and butyl acrylate copolymerized. And the series elastomers exhibited the structure of smectic A, moreover, the modulus increase of the curve for dynamic temperature and modulus change process was mainly due to the formation of liquid crystal phases with hydrogen bond. Meanwhile, self-healing test showed that the series elastomer had excellent self-healing properties, healing efficiency can reach more than 92%, and the two simple ways of drawing and pressing can be used to prepare the photoinduced-deformable actuator with self-healing properties, and presented the well photoinduced deformation. Meanwhile, the samples prepared in two ways exhibit the absolutely opposite photoinduced-deformable behavior by alternate irradiation by UV and visible light. At the same time, the 2D WAXD has explored the mechanism of two opposite phenomenon.