Photoresponsive linear liquid crystal polymers(LLCPs)are attractive because of the excellent stimuli-responsibility and the good processability.In this study,a new photoresponsive LLCP containing azoester(PC11AE6)with...Photoresponsive linear liquid crystal polymers(LLCPs)are attractive because of the excellent stimuli-responsibility and the good processability.In this study,a new photoresponsive LLCP containing azoester(PC11AE6)with good mesophase stability was synthesized by ringopening metathesis polymerization.By introducing photoresponsive azoester mesogenic unit,which has high rigidity and a large lengthdiameter ratio,the resultant polymer possesses a broad mesophase temperature interval(isotropic temperature=180℃).A study on mesophase by 2D-wide angle X-ray diffraction indicated that the mesogens were orientated spontaneously into smectic A phase after annealing.The orientated films and fibres exhibited macroscopic,rapid and reversible deformations under light irradiation as a result of the photoisomerization of azoester as confirmed by UV-Vis absorption spectrophotometry.We anticipate that this work provides a strategy for preparing LLCP with a broad mesophase temperature range,which is positive for potential applications.展开更多
The synthesis of a new azobenzene(azo)-containing main-chain crystalline polymer with reactive secondary amino groups in its backbone and photodeformation behaviors of its supramolecular hydrogen-bonded fibers are des...The synthesis of a new azobenzene(azo)-containing main-chain crystalline polymer with reactive secondary amino groups in its backbone and photodeformation behaviors of its supramolecular hydrogen-bonded fibers are described. This main-chain azo polymer(namely Azo-MP6) was prepared via first the synthesis of a diacrylate-type azo monomer and its subsequent Michael addition copolymerization with trans-1,4-cyclohexanediamine under a mild reaction condition. Azo-MP6 was found to have a linear main-chain chemical structure instead of a branched one, as verified by comparing its ~1H-NMR spectrum with that of the azo polymer prepared via the polymer analogous reaction of AzoMP6 with acetic anhydride. The thermal stability, phase transition behavior, and photoresponsivity of Azo-MP6 were characterized with TGA,DSC, POM, XRD, and UV-Vis spectroscopy. The experimental results revealed that it had good thermal stability, low glass transition temperature,broad crystalline phase temperature range, and highly reversible photoresponsivity. Physically crosslinked supramolecular hydrogen-bonded fibers with good mechanical properties and a high alignment order of azo mesogens were readily fabricated from Azo-MP6 by using the simple melt spinning method, and they could show "reversible" photoinduced bending under the same UV light irradiation and good anti-fatigue properties.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21734003,51573029,51721002)Natural Science Foundation of Shanghai(No.17ZR1440100)Innovation Program of Shanghai Municipal Education Commission(No.2017-01-07-00-07-E00027).
文摘Photoresponsive linear liquid crystal polymers(LLCPs)are attractive because of the excellent stimuli-responsibility and the good processability.In this study,a new photoresponsive LLCP containing azoester(PC11AE6)with good mesophase stability was synthesized by ringopening metathesis polymerization.By introducing photoresponsive azoester mesogenic unit,which has high rigidity and a large lengthdiameter ratio,the resultant polymer possesses a broad mesophase temperature interval(isotropic temperature=180℃).A study on mesophase by 2D-wide angle X-ray diffraction indicated that the mesogens were orientated spontaneously into smectic A phase after annealing.The orientated films and fibres exhibited macroscopic,rapid and reversible deformations under light irradiation as a result of the photoisomerization of azoester as confirmed by UV-Vis absorption spectrophotometry.We anticipate that this work provides a strategy for preparing LLCP with a broad mesophase temperature range,which is positive for potential applications.
基金financially supported by the National Natural Science Foundation of China (Nos. 21574070 and 21774063)Natural Science Foundation of Tianjin (No. 16JCZDJC36800)
文摘The synthesis of a new azobenzene(azo)-containing main-chain crystalline polymer with reactive secondary amino groups in its backbone and photodeformation behaviors of its supramolecular hydrogen-bonded fibers are described. This main-chain azo polymer(namely Azo-MP6) was prepared via first the synthesis of a diacrylate-type azo monomer and its subsequent Michael addition copolymerization with trans-1,4-cyclohexanediamine under a mild reaction condition. Azo-MP6 was found to have a linear main-chain chemical structure instead of a branched one, as verified by comparing its ~1H-NMR spectrum with that of the azo polymer prepared via the polymer analogous reaction of AzoMP6 with acetic anhydride. The thermal stability, phase transition behavior, and photoresponsivity of Azo-MP6 were characterized with TGA,DSC, POM, XRD, and UV-Vis spectroscopy. The experimental results revealed that it had good thermal stability, low glass transition temperature,broad crystalline phase temperature range, and highly reversible photoresponsivity. Physically crosslinked supramolecular hydrogen-bonded fibers with good mechanical properties and a high alignment order of azo mesogens were readily fabricated from Azo-MP6 by using the simple melt spinning method, and they could show "reversible" photoinduced bending under the same UV light irradiation and good anti-fatigue properties.
