【作者】 李艳；

【导师】 赵雄燕； 王鑫；

【作者基本信息】 河北科技大学 ， 材料科学与工程， 2022， 硕士

【摘要】 机械致荧光变色（MFC）材料作为一种刺激响应荧光材料,越来越引起人们的关注,对其性能影响最大的因素是其本身的分子结构,如化学组成、取代基种类、数量、极性等。因为这些因素决定了其分子的最终堆积模式和结晶形态,进而影响材料的整体荧光特性。此外,为了最大程度地发挥小分子荧光化合物的荧光特性,其载体材料的选择也至关重要,聚合物材料具有优异的机械性能和良好的光学透明性,二者的有机结合即可充分发挥小分子化合物优异的荧光性能,又可以充分利用聚合物材料的优势,从而显著提高荧光材料的加工性、稳定性和应用多样性。因此,设计合成具有不同分子结构特点的小分子荧光化合物,并筛选和研究与其相匹配的聚合物基质材料以及二者的共混复合技术意义重大。论文首先设计合成了三种含有不同电负性基团（-CH₃、-CN、-NO₂）的四苯乙烯基染料化合物（DBCNCH₃、DBCNCN、DBCNNO₂）,并分别采用溶液共混和熔融共混技术,将上述合成的染料化合物分别与聚己内酯（PCL）和低密度聚乙烯（LDPE）共混,制备了两类不同样品形态的聚合物基荧光材料。紫外光谱测试结果显示,随着溶剂极性的增加,三种染料化合物的最大吸收波长均发生红移,且随着化合物中取代基电负性的增加,其最大吸收波长的红移程度加大,即DBCNNO₂>>DBCNCN>DBCNCH₃;荧光发射光谱测试结果表明,三种染料化合物粉末样品研磨后,其荧光最大发射波长均发生明显的红移,同时样品的荧光颜色也随之发生改变,用二氯甲烷熏蒸后,研磨样品可恢复到初始状态,说明三种染料化合物均具有MFC特性;含有三种染料化合物的PCL基共混膜拉伸前后的荧光测试结果显示,只有当染料化合物的含量达到一定值后,才会出现MFC现象,且在染料化合物含量相同的情况下,随着染料化合物取代基电负性的增强,样品的最大发射波长发生红移的程度增加;含有三种染料化合物的LDPE基共混样条拉伸前后的荧光测试结果表明,随着共混样条中染料化合物含量的增加,样条的荧光发射波长的红移逐渐明显,呈现聚集诱导发光特性。同时三种共混样条拉伸后,其荧光发射光谱均发生红移,且样条拉伸部位的荧光颜色发生改变,说明掺杂染料化合物的LDPE样条也同样具有MFC性质。其次,论文采用铃木反应,设计合成了含有吡啶环的四苯乙烯基衍生物TPE-PYD,并将制备的TPE-PYD与稀土铕化合物配位得到稀土有机配合物Eu（HFAC）（PYD）,同时通过溶液共混的方法制备了一系列PCL/Eu（HFAC）（PYD）共混膜。测试结果表明,TPE-PYD粉末样品经研磨后,样品荧光颜色由蓝色变为绿色,用二氯甲烷熏蒸后,研磨样品可恢复到初始状态,说明合成的含有吡啶环的四苯乙烯基衍生物具有MFC特性。同时该衍生物与PCL经溶液共混制备的共混膜PCL/TPE-PYD也同样呈现明显的MFC特性;PCL/Eu（HFAC）（PYD）共混膜的荧光发射测试结果显示,与拉伸前相比,拉伸后共混膜的最大发射波长出现了较明显的蓝移现象,同时共混膜拉伸处的荧光颜色也发生了较大的变化,呈现出明显的机械致荧光变色特性;此外测试结果还显示,该共混膜初始样品的最大荧光发射在488 nm左右,荧光颜色为绿色,经365 nm紫外光照射后,在616 nm左右出现一个非常强的荧光发射峰,荧光颜色变为紫红色,表明该共混膜同样具有光致荧光变色性能。最后,论文还将含有吡啶环的四苯乙烯基衍生物TPE-PYD与双炔酸通过氢键自组装和拓扑聚合,制备了TPE-PYD与聚双炔酸的组装体PDA/TPE-PYD,并通过溶液共混的方法,将上述合成的组装体荧光材料分别与PCL和PMMA共混,制备了两类不同性质的聚合物基共混膜PCL/PDA/TPE-PYD和PMMA/PDA/TPE-PYD。测试结果表明,与拉伸前相比,拉伸后PCL/PDA/TPE-PYD共混膜的最大发射波长出现了较明显的蓝移,同时共混膜拉伸处的荧光颜色也出现了较大的变化,表现出明显的机械致荧光变色特性;而PMMA/PDA/TPE-PYD共混膜样品的测试结果则显示,该共混膜经365 nm的紫外光照射后,其最大发射波长由467 nm变为417 nm,蓝移50 nm,共混膜呈现明显的光致荧光变色性能。更多还原

【Abstract】 As one of the stimulus responsive fluorescent materials,mechanofluorochromic（MFC）material has attracted more and more attention.The most important factor affecting MFC material fluorescence performance was its own molecular structure,such as chemical composition,type,quantity and polarity of substituents,because these factors determine the final stacking mode and crystal morphology of MFC molecules,and then affected the overall fluorescence characteristics of materials.In addition,in order to maximize the fluorescence characteristics of small molecule fluorescent compounds,the selection of carrier materials was also very important.Polymer materials have excellent mechanical properties and good optical transparency.The organic combination of fluorescent small molecule compounds and polymers can not only give full play to the excellent fluorescence properties of small molecule compounds,but also make full use of the advantages of polymer materials,so as to significantly improve the processability,stability and application diversity of fluorescent materials.Therefore,it is of great significance to design and synthesize small molecule fluorescent compounds with different molecular structure characteristics,screen and study their matching polymer matrix materials and their blending and composite technology.Firstly,three tetraphenylethylene（TPE）based dye compounds（DBCNCH₃,DBCNCN,DBCNNO₂）containing different electronegative groups（-CH₃,-CN,-NO₂）were designed and synthesized.The above synthesized dye compounds were blended with polycaprolactone（PCL）and low density polyethylene（LDPE）by solution blending and melt blending technology respectively.Two kinds of polymer based fluorescent materials with different sample morphology were prepared.The UV-vis results showed that the maximum absorption wavelength of the three dye compounds had a red shift with the increase of solvent polarity,and the red shift of the maximum absorption wavelength was found to increase with the increase of substituent electronegativity,that is,DBCNNO₂>DBCNCN>DBCNCH₃.The fluorescence emission spectra results showed that the maximum emission wavelength of the three dye compound powders had an obvious red shift after grinding,and the fluorescence color of the samples was also found to be changed.After fumigation with dichloromethane,the ground samples could return to the initial state,indicating that the three dye compounds have MFC characteristics.The fluorescence results of PCL based blend films containing three dye compounds before and after stretching showed that MFC phenomenon could appear only when the content of dye compounds reached a certain value,and when the content of dye compounds was the same,the degree of red shift of the maximum emission wavelength of the sample was found to increase with the enhancement of electronegativity of substituents of dye compounds.The fluorescence results of LDPE based blend samples containing three dye compounds before and after stretching showed that with the increase of the content of dye compounds in the blends samples,the red shift of the fluorescence emission wavelength of the samples was gradually obvious,showing the characteristics of aggregation-induced emission.At the same time,the fluorescence emission spectra of the three blend samples were red shifted after stretching,and the fluorescence color of the stretched part of the sample was also found to be changed,indicating that the LDPE blends doped with dye compounds also had MFC properties.Secondly,TPE-PYD,a tetrastyryl derivative containing pyridine ring,was designed and synthesized by Suzuki reaction.The prepared TPE-PYD was coordinated with rare earth europium compounds to obtain rare earth organic complex Eu（HFAC）（PYD）.At the same time,a series of PCL/Eu（HFAC）（PYD）blend membranes were prepared by solution blending.The results showed that the fluorescent color of TPE-PYD powder sample changed from blue to green after grinding.After fumigation with dichloromethane,the ground sample could return to the initial state,indicating that the synthesized tetrastyryl derivative containing pyridine ring had MFC characteristics.Moreover,it was also found that the blend film PCL/Eu（HFAC）（PYD）prepared by solution blending of the tetrastyryl derivative and PCL also showed obvious MFC characteristics.The fluorescence emission spectra of PCL/Eu（HFAC）（PYD）blend film showed that the maximum emission wavelength of the blend film after stretching was found to have an obvious blue shift compared with that before stretching.At the same time,the fluorescence color at the stretch of the blend film had also changed greatly,showing obvious MFC characteristics.In addition,the results also showed that the maximum fluorescence emission of the initial sample of the blend film was about 488 nm,and the fluorescence color was green.After365 nm UV irradiation,a very strong fluorescence emission peak appears at about 616 nm,and the fluorescence color changes to purplish red,indicating that the blend film had the photochromic property.Finally,the assembly PDA/TPE-PYD of TPE-PYD and polydiyne acid was prepared by hydrogen bond self-assembly and topological polymerization.The above synthesized assembly fluorescent materials were blended with PCL and PMMA by solution blending.Two kinds of polymer based blend membranes PCL/PDA/TPE-PYD and PMMA/PDA/TPE-PYD with different properties were prepared.The results showed that the maximum emission wavelength of PCL/PDA/TPE-PYD blend films was found to have an obvious blue shift after stretching compared with that before stretching.At the same time,the fluorescence color of the blend film also had a great change at the stretch,showing obvious MFC characteristics.The measurement results of PMMA/PDA/TPE-PYD blend membranes showed that after the blend membrane was irradiated by 365 nm ultraviolet light,its maximum emission wavelength changed from 467.2 nm to 417.4 nm,and the blue shift reached 50 nm.The blend membrane showed obvious photofluorescence discoloration properties.更多还原