Preparation And Photodeformability Of Azobenzene-containing Poly（aryl Ether）s With Binaphthalene Groups

Due to the conversion of light energy to mechanical energy,photodeformed azobenzene-containing polymers have become a hot research topic in recent years.The traditional study of photodeformation azobenzene-containing polymers mainly focuses on azobenzene-containing liquid crystal polymers.Although there have been a lot of related researches,azobenzene-containing liquid crystal polymers still have poor thermal stability and mechanical properties.Therefore,azobenzene groups were introduced into the high performance polymer system represented by polyimide and polyaramide to prepare photodeformed azobenzene-containing polymers with better comprehensive properties.However,the imide ring in azobenzene-containing polyimide is rigid and connected with azobenzene group,and the azobenzene-containing polyaramide itself has intramolecular hydrogen bond,so the photodeformation rate of both is slow.Therefore,it is a new scientific problem to develop new photodeformed high performance polymers containing azobenzene.It has been found that azobenzene-containing poly（aryl ether）s have photodeformation properties.Compared with azobenzene-containing polyimide and azobenzene-containing polyarylamide,the photodeformation rate is significantly improved.However,the research on photoinduced deformation of azobenzene-containing poly（aryl ether）s is just beginning,and its photoinduced deformation rate still has room for improvement,and its photoinduced deformation behavior still needs further study.Increasing the free volume of azobenzene-containing polymers can increase the photodeformation rate.Based on the design idea of increasing the free volume of polymers in the gas separation film,we plan to introduce the rigid twisted binaphthalene structure into the azobenzene-containing poly（aryl ether）s system to increase the free volume of the azobenzene-containing poly（aryl ether）s,to improve the photodeformation rate of the material.From the perspective of molecular design,we designed and synthesized a series of azobenzene-containing poly（aryl ether）s containing binaphthalene group,and the thermal,photodeformation properties of the synthesized polymers were studied,the specific research content is as follows:（1）Using（S）-（-）-2,2-dihydroxy-1,1-binaphthyl,4,4’-dihydroxyphenylazodiphenylether,4,4’-（hexafluoroisopropylidene）diphenol and bis（4-fluorophenyl）sulfone as monomers,A series of azobenzene-containing poly（ether sulfone）s with different contents of binaphthalene groups were synthesized by adjusting the feeding ratio of（S）-（-）-2,2-dihydroxy-1,1-binaphthyl and 4,4’-（hexafluoroisopropylidene）diphenol.The thermal properties of the polymers showed that the synthesized poly（ether sulfone）s had high glass transition temperature and good thermal stability.Under the irradiation of 442 nm unpolarized laser,the bending angle of the cantilevers could reach to 90°,and the photodeformation rate of polymer cantilevers increases with the increase of binaphthalene group content.The results show that the method of introducing binaphthalene group into the polymer structure can effectively improve the photoinduced deformation rate of azobenzene-containing poly（aryl ether）s.In addition,this photodeformation of the cantilever that can self-recover in the dark.When the polarization direction of the 442 nm linearly polarized laser is perpendicular to the long axis of the cantilevers,the cantilevers exhibit self-restoring photodeformation behavior,the cantilevers bend away from the laser light source first,then bend toward the direction of the laser light source,and can return to the initial position.The bending angle of polymer away from light source increases with the increase of binaphthalene group content.The photodeformation behavior of polymer can be adjusted by adjusting the polarization direction of the polarized laser.The bending angle,bending rate and recovery rate of the cantilevers decreased with the increase of the cantilever thickness.（2）A difluoride compound containing the R binaphthalene group was designed and synthesized,and it was used as the monomer to polymerize with4,4’-dihydroxyphenylazodiphenylether ether to obtain azobenzene-containing poly（aryl ether ketone）.The thermal properties of the prepared azobenzene-containing poly（aryl ether ketone）showed high glass transition temperature and good thermal stability.The photodeformability of the cantilevers was investigated under 442 nm laser.The results show that the photodeformability rate under 442 nm unpolarized laser is greater than that under 442 nm polarized laser,whose polarization direction is parallel to the long axis of the cantilevers.Photoinduced deformation of the cantilevers induced under 442 nm unpolarized laser and can maintain its deformable shape in dark conditions for several days.Under the irradiation of 442 nm polarized laser（the polarization direction is perpendicular to the long axis of the cantilevers）,the bending angle of the cantilevers could quickly reach to-90°,and then return to the initial position.The recovery rate of the polymer increased with the increase of laser power.