【作者】 王冬梅；

【导师】 吕长利；

【作者基本信息】 东北师范大学 ， 高分子化学与物理， 2017， 硕士

【摘要】 纳米杂化材料由于可以集多种材料的性能于一体,因此在光电、生物医药、能源、环境和催化等领域引起了科研工作者的极大兴趣。金纳米粒子由于其特殊的性质也被广泛地引入到纳米杂化材料当中。而众所周知金纳米粒子的主要问题之一是其在溶液介质中的胶体稳定性。经过大量研究表明,利用聚合物来稳定金纳米粒子的方法,可以有效提高金纳米粒子在溶液中的胶体稳定性。金纳米粒子杂化材料是将金纳米粒子上修饰不同的材料,利用它们之间可能存在的协同作用,提高纳米杂化材料现有性能、赋予其新的性质并改进材料某些性质上的不足,从而在实际应用中发挥更大的作用。近年来将氧化石墨烯、磁性Fe₃O₄材料与金纳米粒子复合构筑的纳米杂化材料更是备受大家青睐,而近年来受到广泛关注的“环境响应性”材料也被应用到纳米杂化材料的合成中。“环境响应性”材料是指一类能够对外界刺激（温度、pH、磁场、光照等）做出智能响应从而改变自身的物理或化学性质的材料。这类材料无论在性能还是实际应用方面都具有很好的应用前景。本论文选择金纳米微粒为构筑基元之一,利用具有配位作用的含环硫单元的热响应聚合物大分子配体为稳定剂,并集成还原氧化石墨烯和磁性Fe₃O₄材料于一体,旨在构筑一类组装形态可控、具有热敏响应以及可循环利用的多功能集成的新型金纳米杂化材料体系并研究其在催化方面的应用。本论文的主要研究内容包括以下两个部分工作:一、首次采用可逆加成-断裂链转移聚合（RAFT）方法将含有环硫官能团的甲基丙烯酸环硫丙酯（ETMA）和具有热敏性质的异丙基丙烯酰胺（NIPAM）以及水溶性的聚乙二醇甲基丙烯酸酯（PEGMA）共聚制备了温敏性嵌段共聚物P（NIPAM-co-ETMA）-b-P（PEGMA）（P）,并研究了它们的胶束组装行为。以嵌段聚合物中的环硫基团为配体,通过原位（in-situ）还原法在配位胶束中制备了不同尺寸和形貌的金纳米微粒（Au NPs@P）。我们还探究了聚合物对原位合成金纳米微粒的尺寸和形貌的影响,并以NaBH4还原对硝基苯酚为模型反应探究所构筑的Au NPs@P杂化材料的催化性能。主要研究了金纳米粒子的尺寸效应、还原剂和催化剂的用量对催化反应的影响。结果表明大分子配体P的引入改善了Au NPs@P杂化催化剂的稳定性,对NaBH4还原对硝基苯酚的反应表现出优异的催化活性,并且催化活性随着杂化催化剂中Au NPs尺寸的增大而提高。此外,所利用的热敏性大分子配体还赋予金纳米微粒在催化还原硝基苯酚时具有热“开关”的智能可控特性。二、发展了一种用于有机催化反应的温度响应性聚合物功能化的还原氧化石墨烯（RGO）@Fe₃O₄@Au NPs磁性纳米复合材料（Au NPs@GFDP）的构筑新方法。我们首先通过一步法化学合成了RGO/超顺磁性Fe₃O₄纳米粒子杂化材料（RGO@Fe₃O₄）,然后利用贻贝灵感化学通过多巴胺在弱碱性水溶液中的自聚合在RGO@Fe₃O₄表面修饰上聚多巴胺（PDA）层得到RGO@Fe₃O₄@PDA复合物（GFD）。我们还利用可逆加成-断裂链转移聚合（RAFT）法合成了含有环硫官能团的甲基丙烯酸环硫丙酯（ETMA）和具有热敏性质的异丙基丙烯酰胺（NIPAM）的共聚物配体P（NIPAM-co-ETMA）（P）,然后通过简单的迈克尔加成反应（Michael addition reaction）成功地将共聚物接枝到GFD表面（GFDP）。最后利用共聚物中的环硫基团作为配体,通过在GFDP的溶液中原位还原HAuCl4构筑了Au NPs/GFDP纳米杂化材料（Au NPs@GFDP）。Au NPs@GFDP在水溶液中表现出优异的分散性和稳定性。我们研究了Au NPs@GFDP对不同硝基苯酚的催化还原实验。结果表明:Au NPs@GFDP作为催剂在NaBH4还原硝基苯酚的反应过程中展现了较高的催化性能;更重要的是,由于磁性Fe₃O₄纳米颗粒的存在使得Au NPs@GFDP纳米杂化材料很容易进行磁性分离回收和循环利用,并且催化剂的重复利用的效率较理想。由于Au NPs@GFDP催化剂表面带有温敏性的PNIPAM链段,因此在硝基苯酚的催化还原过程中表现出较好的温度响应行为。本工作所发展的构筑温度响应性纳米杂化材料的方法对于各种工业催化具有潜在的应用价值。更多还原

【Abstract】 Nanohybrid materials have aroused great interest of researchers in the optoelectronics,energy,environment and catalysis fields because they integrated the properties of various materials in one.Especially,the gold nanoparticles（Au NPs）have also been widely introduced into the nanohybrid materials due to its special performance.However,it is well known that one of the main problems of gold nanoparticles is its colloidal stability in solution media.A large number of studies have shown that the method using polymer to stabilize nanoparticles can effectively improve the colloidal stability of Au NPs in solution.The Au NPs hybrid materials can be prepared by modifying the gold nanoparticles with different materials,and taking the advantage of the possible synergies between them to improve the existing properties of nanohybrid materials and to endow them with new functionality and to improve some deficiencies in nature of the materials,which can play a greater role in practical applications.In recent years,the nanohybrid materials constructed by integrating Au NPs with graphene oxide（GO）and magnetic Fe₃O₄ are much favored by everyone.In addition,the “environmentally responsive” material,which has been widely concerned in recent years,has also been introduced into nanohybrid materials.The “environmentally responsive” material refers to a class of materials that can alter their physical or chemical properties by making intelligent responses to external stimuli（temperature,pH,magnetic fields,light,etc）and this kind of materials has a very good application prospect in both performance and practical application.In this thesis,gold nanoparticles were selected as one of the building units,and the episulfide-containing thermo-responsive polymer ligand was used as the stabilizer.And integrated with reduced graphene oxide and magnetic Fe₃O₄ magnetic materials,we successfully constructed a new type of gold nanohybrids with controllable self-assembled morphology and multifunctional integration of thermo-responsive and recyclable properties,and studied their applications in catalysis.The detailed content of this thesis includes the following two parts:In the first part,we firstly designed and prepared the temperature-responsive block copolymer P（NIPAM-co-ETMA）-b-P（PEGMA）（P）from episulfide-containing 2,3-epithiopropyl methacrylate（ETMA）as ligand and N-isopropylacrylamide（NIPAM）with thermo-responsive properties as well as water-soluble poly（ethylene glycol）methylether methacrylate（PEGMA）via reversible addition fragmentation chain transfer（RAFT）polymerization.And the micellar assembly behavior of this block copolymer was also studied.Gold nanoparticles（Au NPs@P）with different sizes and morphologies were prepared by in-situ reduction method in the coordination micelles using the episulfide group in the block polymers as ligand.We also investigated the effect of the polymer on the size and morphology of Au NPs obtained by in situ synthesis route,and the catalytic performance of the resulting Au NPs@P hybrids was studied by using a model reaction of catalytic reduction of p-nitrophenol by NaBH4.The effects of the size of Au NPs and the amount of reducing agent and catalyst on the catalytic reaction were mainly studied.The results showed that the introduction of polymer ligand P improved the stability of Au NPs@P hybrid catalyst which exhibited excellent catalytic activity for the reaction of p-nitrophenol,and the catalytic activity increased with the increase size of Au NPs in the hybrid catalyst.In addition,the use of thermo-sensitive polymer ligands also imparted the intelligent controllable properties to Au NPs with thermal “switching” when catalyzing the reduction of nitrophenol.In the second part,we developed a new method to construct the temperatureresponsive polymer functionalized reduced graphene oxide（RGO）@Fe₃O₄@Au NPs magnetic nanocomposites（AuNPs@GFDP）for organic catalytic reaction.We first synthesized superparamagnetic Fe₃O₄ nanoparticles（NPs）on reduced graphene oxide（RGO@Fe₃O₄）via one-pot chemical functionalization method,and then a polydopamine（PDA）layer was formed on the surface of RGO@Fe₃O₄ to obtain RGO @ Fe₃O₄ @ PDA composite（GFD）using the self-polymerization of dopamine（DA）in the weak alkaline aqueous solution by mussel-inspired chemistry.The thermo-responsive copolymer ligand of poly（N-isopropylacrylamide-co-2,3-epithiopropyl methacrylate）P（NIPAM-co-ETMA）（P）was also synthesized via a reversible addition fragmentation chain transfer（RAFT）polymerization and was grafted onto the surface of GFD（GFDP）via a simple Michael addition reaction.Finally,the episulfide groups in the copolymer were used as ligands to fabricate Au NPs functionalized GFDP nanocomposites through in situ reduction of HAuCl4 in GFDP solution.Au NPs@GFDP nanocomposite exhibited excellent dispersibility and stability in aqueous solutions.We studied the catalytic reduction of different nitrophenols by Au NPs @ GFDP.The results showed that Au NPs@GFDP as a catalyst during the reaction of reduction nitrophenol by Na BH4 had a higher catalytic performance.More importantly,due to the presence of magnetic Fe₃O₄ nanoparticles,the Au NPs @ GFDP nanocomposite materials were easily separated and recycled by magnetic separation and the efficiency of catalyst reuse was also very ideal.The catalytic reduction reaction also exhibited excellent temperature-responsive behavior due to the presence of thermo-sensitive PNIPAM segments on the surface of Au NPs@ GFDP catalyst.The method of constructing temperature-responsive nano hybrid materials developed by this work may be of great potential for various industrial catalytic applications.更多还原