【作者】 王璟；

【导师】 肖惠宁； 周雪松；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2014， 博士

【摘要】 纤维素是地球上最丰富的的可再生生物质资源，由于其良好的生物相容性、生物降解性和无毒性等特征，纤维素及其衍生物除了在传统的工业领域得到广泛的应用外，在生物制药、食品工程和生物医学材料等领域有着十分广阔的应用前景。以纤维素为基材制备的环境敏感性纤维素基水凝胶现在已成为各国研究的热点，其在药物控释、生物透镜和金属离子废水处理等方面都有着潜在的应用前景。纤维素基水凝胶的制备一般有物理方法和化学方法，而从制备反应介质来分，可分为非均相反应和均相反应两种类型。由于纤维素分子间较高的氢键结合和较高的结晶度，导致其在化学改性方面的效率低下，所以不断寻找优良的纤维素溶剂体系也是各国科学家们一直努力的方向。本论文以氯化锂/N,N-二甲基乙酰胺（LiCl/DMAc）溶剂体系作为纤维素化学改性的反应介质，分别采用常规的自由基聚合方法和原子基团转移自由基聚合（ATRP）方法制备出具有不同结构的纤维素基水凝胶。1、采用常规自由基溶液聚合方法，构建具有半互穿网络(Semi-IPN)结构的纤维素/聚异丙基丙烯酰胺（cellulose/PNIPAAm）复合水凝胶。研究中以微晶纤维素（MCC）和异丙基丙烯酰胺（NIPAAm）为原料，N,N′-亚甲基双丙烯酰胺（MBAAm）为交联剂，过氧化苯甲酰（BPO）为引发剂。运用傅立叶红外光谱（FTIR）、扫描电子显微镜（SEM）、热重分析（TGA）对水凝胶进行结构、形貌和热学性能进行表征。结果表明这种Semi-IPN结构的水凝胶具有多孔三维结构，和良好的温度敏感性。探讨了交联剂MBAAm的用量对水凝胶的形态结构、溶胀/消溶胀行为以及温度响应性的影响。结果发现随着交联剂用量的提高，水凝胶中PNIPAAm组分增加，孔隙减小且孔壁加厚，这引起了水凝胶平衡吸水溶胀率的降低，溶胀速率和消溶胀速率也随之降低，这表明可通过水凝胶的交联密度控制水凝胶的溶胀行为。另外，以亚甲基蓝为药物模型，研究了该系列水凝胶的吸附和控释性能。2、采用ATRP方法，以2-溴代异丁酰溴（BiBB）为引发剂，溴化亚铜/N,N,N′,N′,N′-五甲基二乙烯基三胺（CuBr/PMDETA）为催化剂体系，在纤维素分子链上引入温敏性聚合物链段PNIPAAm和不饱和双键。通过紫外光辐照交联制备出新型纤维素基温敏性水凝胶。用FTIR、DSC和SEM对该水凝胶的化学结构、凝聚态结构以及表面形貌等进行表征，发现该系列水凝胶具有温度负响应特性，并且其临界相转变温度（LCST）随着纤维素大分子引发剂阶段中BiBB用量的增加而升高。3、采用常规自由基聚合方法，用丙烯酸（AA）和纤维素制备具有Semi-IPN结构的水凝胶，成功在水凝胶网络上引入聚丙烯酸链段，使得水凝胶具有良好的pH敏感性。研究了水凝胶的溶胀动力学。水凝胶对金属离子Cu2+具有良好的吸附作用，并通过线性方程模拟，发现水凝胶的吸附动力学符合准二级反应方程，属于化学吸附机理。该水凝胶在金属离子废水处理方面具有潜在应用。4、用AA、NIPAAm和纤维素制备了具有pH和温度双响应性的Semi-IPN结构水凝胶。该水凝胶具有无规则小孔径的三维网络结构，其具有良好的温度和pH响应性。对水凝胶在37°C的体外释药曲线进行了模型计算和分析，结果发现载药水凝胶在不同的pH值条件下的释放动力学模型不同，释放机制随着时间的变化而变化。更多还原

【Abstract】 Cellulose is the most abundant organic raw material. This inexpensive, biodegradableand renewable resource has received a great deal of attention for its physical properties andchemical reactivity. Many properties of cellulose, both physical and chemical are significantlydifferent from those of synthetic polymers. Therefore, cellulose and cellulose derivatives findapplications in areas as diverse as composite materials, tissue engineering scaffold, drugdelivery systems and personal care products. However, the unique physical properties ofenvironmentally sensitive hydrogels based on cellulose have sparked particular interest intheir applications. As a result, hydrogels are commonly used in tissue engineering, drugdelivery, diagnostics, and cellular immobilization, separation of biomolecules and adsorptionof heavy metals.In this work, a series of cellulose based hydrogels were synthesized in LiCl/DMAcsolution.1. A new kind SIPN cellulose hydrogel was synthesized using NIPAAm and cellulose.The swelling behaviors and temperature sensitivities of the hydrogel were researched in detail.It was found that the swelling ratios of the hydrogels decreased with increasing temperature.The adsorption and release behavior of the hydrogel for cationic methylene blue wasinvestigated. The morphology, thermal behavior and thermal stability of the hydrogel werestudied by SEM, DSC and TGA.2. A big molecular initiator was synthesized by using cellulose and BiBB. Then thecellulose-PNIPAAm-PEGDMA was synthesized by ATRP. Lastly prepared the cellulose basedhydrogel using the cellulose grafted polymer. The swelling behaviors and temperaturesensitivities of the hydrogel were researched in detail. It was found that the LCST of thehydrogel increased with increasing BiBB.3. A pH sensitive cellulose hydrogel was synthesized. The structure and morphology ofthe hydrogel were analyzed by FTIR and SEM. The prepared hydrogel beads showed goodadsorption ability for heavy metal ions.4. A pH and thermal double sensitive cellulose based hydrogel was prepared. Thestructure and morphology of the hydrogel were analyzed by FTIR and SEM. The drug releasebehavior was investigated through model calculations and analysis, combined with the resultsof experiments.更多还原