Preparation Of Photochromic Polyesters And Fibers Based On Azobenzene Derivatives And Performance Studies

With the rapid development of society,stimuli-responsive materials have received extensive attention and have become one of the research hotspots in recent years.Polyester materials are widely used in engineering plastics,fibers and other fields.Among them,photochromic polyester materials have broad application prospects in functional clothing,textile anti-counterfeiting and other fields.However,the synthesis and processing of polyester materials are carried out at relatively high temperatures,and the traditional photochromic groups have poor high temperature resistance and are prone to failure at high temperatures.Therefore,the development of photochromic molecules suitable for polyester materials and high temperature resistant photochromic polyester materials has become an urgent scientific problem to be solved,and is of great significance in the mass production of photochromic polyester materials.First,5-（4-（decyloxy）phenyl）diazo)phthalate dimethyl（AZO₂）was designed and synthesized in this paper.)characterized the molecular structure of the intermediate（AZO₁）compound and the product（AZO₂）,and characterized the relative molecular mass of the compound by liquid chromatography-mass spectrometry（LC-MS）.UV-vis was used to characterize the ultraviolet absorption spectrum and photostimuli response performance of the compound.The test results of the thermogravimetric analyzer（TGA）showed that the azobenzene derivative only lost 5%of its weight at 278°C,which can meet the requirements of the subsequent polymerization reaction.require.Secondly,polybutylene terephthalate（PBT）with different contents of azobenzene derivatives was synthesized by transesterification method.The results of hydrogen nuclear magnetic resonance spectrum（¹HNMR）,Fourier transform infrared spectrum（FTIR）and EDS spectrum showed that the azobenzene derivative（AZO₂）was successfully integrated into the molecular chain of the polymer through a covalent bond;a thermogravimetric analyzer（TGA）characterized the thermal stability of the polymer;the results of differential scanning calorimetry（DSC）and X-ray diffractometer（XRD）showed that the intercalation of azobenzene derivatives reduced the crystallization temperature of the polymer first After increasing,how does the crystallization property change;Using a UV-visible spectrophotometer and a UV lamp with a wavelength of 365 nm to characterize the color-changing sensitivity and reversible cycle performance of the polymer,the results show that the polymer has responsiveness to light stimulation,high sensitivity,and good Cycle stability:Photochromic PBT was trial-produced in a 5 L polymerization reactor,and photochromic PBT fabrics were obtained through sheeting,spinning,weaving and other processes,which are stable to the chemical structure,thermal properties and photochromic cycle of the product The properties have been studied,indicating that the polymer has good high temperature stability and processing performance,and has the prospect of industrial production..Finally,in order to further improve the photochromic sensitivity of the polymer,polytetrahydrofuran（PTMG）was used as the soft segment,polybutylene terephthalate（PBT）was used as the hard segment,and azobenzene derivatives（AZO₂）as a photosensitive group to synthesize photochromic polyether ester elastomers with different molecular weights and contents of soft segments.The results of Fourier transform infrared spectroscopy（FTIR）,ultraviolet-visible spectrophotometer（UV-vis）,and hydrogen nuclear magnetic resonance（¹HNMR）showed that azobenzene derivatives had been successfully integrated into the polymer main chain through covalent bonds,and Compared with photochromic PBT,polyetherester elastomer has higher photochromic sensitivity.The results of thermogravimetric analysis（TGA）and differential scanning calorimetry（DSC）show that the polymer has good thermal stability and can meet the processing requirements.The addition of azobenzene derivatives makes the melting temperature and The crystallization temperature decreases,and when the molecular weight of the soft segment is the same,the more the content of the soft segment,the lower the melting temperature and crystallization temperature of the polymer;The higher the temperature.The mechanical properties of the polymer were characterized by a universal tensile testing machine,and the crystallization properties of the polymer were characterized by an X-ray diffractometer（XRD）.The results of polarizing microscope showed that the orientation occurred in the polyetherester elastomer fiber,which reduced the entanglement of polymer chains and was more conducive to improving the stimulus response rate of the polymer.