In this paper, a copolymer containing photosensitive group was used as photo-alignment film through linearly polarised ultraviolet irradiation to a varying heating rate for an investigation of liquid crystal orientation. When the polymer film is exposed to linearly polarised ultraviolet, it can generate a polarisation-axis selective photoreaction. Then the thin film underwent thermally enhanced photoinduced molecular reorientation followed by subsequent annealing. Fixed exposure energy was 324 mJ cm−2 and annealing temperature was 98°C, heating rates varied from 5 to 30 S °C−1, a large anisotropy was generated. According to the method mentioned in the paper to calculate the enhanced ratio, the best heating rate is 20 S °C−1.
Da Zhang,Qing-Shuang Li,Zi-Xuan Liang,Xia-Chao Chen,Junran Hao,Juming Yao,Chun-Xin Lu,Yahong Zhou,Lei Jiang
Although many methods have been developed to create porous structures within polyelectrolyte films, it remains a challenge to conveniently define the spatial distribution of these structures. Herein, a simple, universal strategy with a high flexibility in programming porous regions throughout polyelectrolyte films is reported. This strategy is performed with the aid of laser scanning and the emergence of porous regions precisely tails after the moving path of laser beams. Quite different from previous strategies, the pore-forming mechanism relies on laser-triggered generation of gas to foam the films, which can be regulated by the content of photo-sensitive groups, the intensity of laser beams, and the supramolecular interactions between polyelectrolyte chains. A prerequisite to succeed the foaming of polyelectrolyte films is to irradiate them under water, where the mobility of polyelectrolytes is activated to accommodate the pore formation within the films. Although many pore-forming mechanisms involve aqueous systems, the porous structures here can be well preserved during drying procedures, which is hardly realized for conventional methods due to the formation of capillary pressure. The resulting polyelectrolyte films with patterned porosity can be quite useful in many fields, including but not limited to information display, surface wettability, and cell behavior manipulation.
Adhesive patches are advanced but challenging alternatives to suture, especially in treating fragile internal organs. So far there is no suture-free adhesive patch based on metabolizable poly(amino acid) materials with excellent mechanical strength as well as immunomodulation functionality. Here, a polyglutamic acid-based elastic and tough adhesive patch modified by photosensitive groups on the surface to achieve robust light-activated adhesion and sealing of flexible internal organs is explored. With the porous internal morphology and excellent biodegradability, the patches promote regeneration through a macrophage-regulating microenvironment. Treated rabbits achieve rapid full-thickness gastric regeneration with complete functional structure within 14 d, suggesting its robust tissue adhesion and repair-promoting ability.
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