【作者】 王斌；

【导师】 陈克复；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2014， 博士

【摘要】 天然高分子化合物资源丰富、来源广泛、可生物降解，它们是取之不尽、用之不竭的重要绿色化工原料。天然高分子化合物因具有多种功能基团，可以通过物理、化学等各种方法赋予其新的功能。本研究将两种螺吡喃单体引入天然多糖基化合物体系中，设计并合成了具有光活性的天然高分子材料，赋予其独特的光学性能，并研究了相关机理。相关研究成果能为我国制浆造纸工业提高产品附加值，开发新的功能性产品，为天然高分子化学工业研发新型感光材料、防伪材料、传感材料、光调节的缓释材料提供理论支撑。本论文主要内容和结果如下：设计并合成两种光响应单体—羧基螺吡喃(SPCOOH)和丙烯基螺吡喃化合物(SPMA)。对于螺吡喃衍单体，研究了取代基及溶液介质对光致变色特性影响；分析SPMA在不同溶剂中的消光过程动力学，结果表明螺吡喃化合物在不同溶剂中的消光速率是：二氯甲烷＞甲苯＞丙酮，且在溶液中的消光过程符合一级动力学方程。合成了含螺吡喃疏水侧链的双亲支链淀粉共聚物(SPP)，利用其疏水基在水溶液中的交联缔合作用，制备出光响应的纳米水凝胶。纳米水凝胶的平均粒径和分子量随紫外光照射而增大，且光响应水凝胶分为三种状态—紫外光照射开环(Mer-form)、可见光照射闭环(SP-form)、黑暗条件下中间态(Mer-sp-form)。研究了SPP水凝胶退色动力学以及在DMSO/H2O溶液中的聚集过程，实验结果表明SPP的退色速率随水比例升高而降低。以芘为模拟药物，研究了SPP水凝胶在PBS缓冲溶液中的包载及光控释放药物的能力，包载率和载药量随着凝胶比例增加而增大，螺吡喃处于开环状态下的药物释放量大于闭环状态的释放量，因此可通过光控来调节疏水性药物的释放速率。采用原子转移自由基聚合(ATRP)的方法设计并合成了EC-g-PHEMA-g-PSPMA三嵌段聚合物，通过改变反应配比，制备出不同嵌段接枝密度和接枝长度的聚合物，动力学分析证明，实验所采用的体系适合ATRP反应且聚合反应是活性/可控的。同时，对EC-g-PHEMA-g-PSPMA胶束溶液的聚集态进行分析，结果表明，胶束的聚集体形态主要受亲水/疏水段比例影响较大。疏水核所占比例越大，越有利于胶束之间的相互吸附，亲水链所占比例大，有利于胶束之间相互分离。PSPMA的段链越长，聚合物闭环响应时间越长，这是由于开环部花菁(MC)结构产生过多，形成空间位阻越大，导致闭环时间缓慢。PSPMA受紫外光激发转变为亲水的MC结构，使胶束分离成二级小胶束，经可见光照射，聚合物聚集形态又返回至原始状态。最后，利用EC-g-PHEMA-g-PSPMA在水相中聚集形态的之间的相互转变，成功实现了药物的负载与光控释放。将壳聚糖季铵盐附着于木质纤维表面，赋予纤维正电性，利用库仑引力提升羧基螺吡喃(SPCOOH)与纤维结合效率，制得光响应纤维。改性后纤维的吸附动力学研究发现，螺吡喃对纤维的吸附过程符合准一级动力学方程，且随着温度升高，螺吡喃在纤维上的吸附速率常数增大。利用光响应纤维与植物纤维配抄的方法，制得光响应型纸样，在紫外灯照射下光响应纤维显示出红色荧光，且光响应纤维由无色变为红色，经可见光照射又恢复至无色，在可见光下光响应纸基与普通纸张没有差别，具有防伪特征。利用滤纸纤维表面羟基的活性，通过酰化反应制备出大分子引发剂，成功引发ATRP反应，将丙烯基螺吡喃(SPMA)接枝聚合在纤维表面上，实现纤维表面的光功能化组装。功能化纸基由于螺吡喃接枝聚合于纤维表面，使纤维表面亲水基团相对减少，导致功能化纸基的亲水性略有下降。光功能化纸基在紫外光照射下，显示出明显的红色荧光，移去紫外光，纸基由无色变为红色，经可见光照射时，红色又变为无色，这是由于纤维表面接枝的螺吡喃聚合物受紫外光-可见光照射，其化学结构随之产生开环-闭环，最终实现显色-退色的光可调控效果。功能纸基在紫外光下产生荧光并变色的双重效果，可应用于防伪包装材料等方面。更多还原

【Abstract】 As a sort of wide material sources, excellent repetition and tunable structure,polysaccharide compounds suit for many different demands. Polysaccharide molecule chaincontains a lot of functional groups, such as hydroxyl, amino, carboxyl, so in this paper twokinds of spiropyran monomers were introduced to natural polysaccharide compound system,to design and synthesis of natural macromolecular materials with photo-responsivecharacteristics, given its unique optical properties. This topic results provided theoreticalsupport for the development of new photosensitive material, anti-counterfeiting materials,sensing materials, and light controlled release materials. The main content and the results ofthis paper are as following:According to the structure of polysaccharide compounds, two kinds of light-responsivemonomers (SPCOOH and SPMA) were designed and prepared. For spiropyran monomers,their photochromic properties were affected by substituent groups and solvent. SPMAextinction kinetic dynamics in different solvents were also analyzed. The results have shownthat the closing reaction of SPMA was a first order reaction, and the reaction rate indichloromethane, methylbenzene and acetone reduced in turn.Amphiphilic polymer with hydrophobic spiropyran and starch was synthesized.According to its hydrophobic group crosslinking association in aqueous solution,light-responsive nanogels were prepared. The Mwand Dhof the nanogels significantlychanged after irradiation under different wavelengths of light. The synthesized SpP nanogelsexisted in the following three states: Mer-Sp-form (515nm), Mer-form (535nm), andSp-form. SPP extinction kinetic dynamics and aggregation process in DMSO/H2O solventswere also analyzed. The closing reaction rate of SPP decreased with water ratio rise. The druguptake and release properties were investigated by using pyrene as a model drug. The resultsindicate that the loading efficiency increased when the feeding ratio of SpP to pyreneincreased. The release amount and rate decrease in the following order: Mer-Sp-form Mer-form Sp-form. So the release rate can be adjusted by light controlled.A light-responsive triblock copolymer of ethyl cellulose-g-poly (2-hydroxyethlmethacrylate)-g-poly (spiropyran ether methacrylate)(EC-g-PHEMA-g-PSPMA) wasprepared by atom transfer radial polymerization. Different block grafting density and lengthof grafted polymer was preparaed by changing reactive ratio. Dynamics analysis proved thatthe experiment system was suitable for ATRP and polymerization reaction was active/controlled. At the same time, the EC-g-PHEMA-g-PSPMA micellar solution ofaggregation were analyzed, and the results show that the micellar aggregation morphologywas mainly affected by hydrophilic/hydrophobic ratio. The larger the proportion ofhydrophobic core, the more adsorbed between micelles. The larger proportion of hydrophilicchain, the more separated between micelles. For PSPMA segments, the polymer closed-loopresponse time would long if have high degree of polymerization with PSPMA. The spacesteric hindrance may form with more MC structure which lead to greater slowly during theclosed-loop process. The micelle diameter can be controlled by UV and visible light. Micellescan be modulated by changing the ratio of hydrophilic PHEMA to hydrophobic PSPMA.Probe pyrene as a hydrophobic model drug was loaded onto micelles. Therefore, drug releasecould be controlled by changing light.Chitosan quaternary ammonium salt attached to surface of wood fiber. The fiber showedelectropositive and light-renponsive due to SPCOOH combined with fiber. The resultsshowed that adsorption kinetics of modified fiber showed fitted quasi first order equation.And with increasing temperature, adsorption rate constant increased on fiber. An experimentof making light-responsive paper with light responsive fiber was carried out. Light-responsivefiber showed red fluorescence under ultraviolet light irradiation, and the fiber changed tocolorless under visible light irradiation. The responsive paper has no difference with theordinary paper. It has the security features.Fiber macromolecular initiator was firstly synthesized by direct acylation of fiber with2-bromopropionyl bromide. And a light-responsive fiber grafed poly (spiropyran ethermethacrylate)(Fiber-g-PSPMA) was prepared by atom transfer radial polymerization. Thehydrophilicity of functionalized paper was reduced due to spiropyran graftedpolymerizationon the fiber surface. Functionalized paper showed red fluorescence under ultraviolet lightirradiation, and the paper changed to colorless under visible light irradiation. This because Spunderwent isomerization, it changed into merocyanine (Mer) under UV. And the Mermolecule was exposed to visible light, it reverted into colourless Sp. Functionalized paper hasdouble fluorescent and color changing effects under ultraviolet light, which can be applied toanti-counterfeiting packaging materials.更多还原