【作者】 唐征海；

【导师】 郭宝春；

【作者基本信息】 华南理工大学 ， 材料加工工程， 2014， 博士

【摘要】 石墨烯具有独特的电子特性和物理性质，作为聚合物纳米填料，石墨烯具有非常高的增强效率和效应，同时还可赋予复合材料功能特性。但聚合物/石墨烯复合材料的制备主要受限于石墨烯的宏量制备，石墨烯在聚合物中均匀分散，聚合物-石墨烯界面结构设计，以及缺乏对构效关系的认识。基于这一现状，作者开展了石墨烯的修饰及相关聚合物/石墨烯复合材料的研究，主要内容如下。（1）通过乳液共混和原位界面裁剪，设计和制备了具有氢键界面或离子键/氢键界面结构的丁苯吡橡胶（VPR）/GO复合材料。详细研究了界面结构对复合材料性能的影响。对比氢键界面结构的复合材料，离子键界面结构的复合材料具有更优异的力学性能和气体阻隔性，这是因为在复合材料中离子键结构的界面作用更强且GO均匀更均匀。（2）采用常用、廉价的染料和荧光增白剂为改性剂，通过非共价键修饰石墨烯，制备了在水中以高浓度稳定分散的单层石墨烯。改性剂分子通过π-π和阳离子-π吸附到石墨烯片上，从而阻止石墨烯的团聚。以聚乙烯醇（PVA）和壳聚糖（CS）为模型聚合物，制备了相应的聚合物/石墨烯复合材料。加入少量石墨烯，复合材料的拉伸强度、拉伸模量和韧性都同时大幅度提高，这是由于石墨烯均匀分散在复合材料中，且平行于样品表面排列，另外改性剂分子有效提高了石墨烯-聚合物界面结合。（3）通过非共价键改性策略，在石墨烯表面引入离子对，制备了在室温和无溶剂情况下均匀分散和具有流体性质的石墨烯离子材料（G-NIM）。G-NIM以单片层石墨烯为核，非共价键改性为晕层，柔性分子聚醚胺为壳三部分组成，聚醚胺通过离子键连接并均匀包覆在石墨烯表面。G-NIM具有两亲性，在多种溶剂中呈现稳定和超高浓度分散（浓度高达500mg/ml）。（4）以生物来源的单体为原料，采用缩聚反应合成了以羟基封端的生物基聚酯（BE）。利用简单有效的溶剂交换法制备了在多种有机溶剂中呈稳定单层分散的GO分散液。通过GO边缘的羧基与BE端羟基之间的酯化反应，将BE接枝到石墨烯上制备了BE/石墨烯复合材料。由于BE分子链可以连接不同石墨烯片层，有利于石墨烯相互搭接形成导通网络，因此复合材料的电导率和热导率同时显著提升。（5）以气相增长碳纳米纤维（VGCF）为石墨烯的纳米稳定粒子，制备了在NMP中稳定分散的VGCF-G杂化填料。VGCF通过π-π作用吸附在石墨烯片层上，阻止石墨烯团聚；同时二维石墨烯片层作为VGCF载体，减少VGCF的缠结。在VGCF-G填充的复合材料（BE/VGCF-G）中，VGCF和石墨烯都均匀分散，且VGCF-BE界面作用明显增强。对比BE/VGCF复合材料，VGCF-G对提高复合材料的力学性能和导电率有显著的协同效应，而且BE/VGCF-G复合材料有更优异的电驱动和红外驱动形状记忆行为。（6）从特定的基团相互作用出发，利用单宁酸修饰的石墨烯（TAG）与埃洛石纳米管（HNTs）之间的氢键和配位作用，制备了HNTs-TAG杂化填料。通过胶乳共混法，将杂化填料与丁苯橡胶（SBR）胶乳复合制备SBR/HNTs-TAG复合材料。杂化填料在SBR中互相搭接形成完善稳定的3D填料网络结构。完善的填料网络可以有效“包埋”橡胶分子，增加流体力学体积效应；同时TAG的加入促进HNTs在基体中均匀分散，同时增强了HNTs与SBR的界面作用，因此杂化填料对SBR具有显著的协同增强效应。更多还原

【Abstract】 Graphene is under the spotlight of the science and technology community owning to itsunparalleled properties. As nanofiller for polymer, graphene has exceptional reinforcingefficiency towards polymer matrix, and it can endow the composites with functionalproperties. However, the real-life applications of graphene in polymer composites are greatlylimited by the large-scale production, the uniform dispersibility of graphene in polymermatrix, the design of interfacial structures, and being lack of the understanding of therelationship between the structures and performances of the composites. Accordingly, in thepresent dissertation, we focused on the studies on the functionalization of graphene andpolymer/graphene composites.(1) The elastomeric hybrids consisting of graphene oxide (GO) sheets were fabricatedby utilizing butadiene-styrene-vinyl pyridine rubber (VPR) as the host through co-coagulationprocess and in situ formation of an ionic bonding interface. The VPR/GO composites with anormal hydrogen bonding interface were also prepared. The mechanical properties and gaspermeability of these hybrids with an ionic bonding interface were obviously superior to thoseof the composites with a hydrogen bonding interface, which was due to the fine dispersion ofGO and strong ionic interface in the hybrids.(2) Individually dispersed graphene colloid was prepared using common andcommercially available fluorescent whitening agents (FWAs) and dye as nano-covalentmodifiers. The modifiers were successfully anchored onto graphene sheets by π-π andcation-π interaction to prevent the aggregation of graphene. Subsequently, the obtainedgraphene was incorporated into polyvinly alcohol and chitosan (CS) by solution casting tofabricate PVA/graphene and CS/graphene composites. The concurrently significantimprovements in tensile strength and toughness of the composites were observed, which wasrelated to the uniqueness interfacial structure and morphology of the composites. It wasdemonstrated that graphene was homogeneous dispersed in the composites and was alignedparallel to the surface of composite films. Besides, the modifiers located in the graphene and polymer interface zone strengthened the interfacial interaction between them.(3) Graphene material with liquid-like behavior was synthesized through decoratinggraphene with a generic non-covalent fashion and subsequently combining them with bulkypolymer chains. Individually dispersed graphene core was first prepared through chemicalreduction of GO by using fluorescent whitening agent VBL as a non-covalent modifier. Thenegative groups of VBL which were anchored onto the graphene sheets imparted grapheneanionic characteristic. Combination of the modified graphene with bulky Jefamine2070chains through electrostatic interaction yielded homogeneous graphene fluid, i.e.graphene-based nanoparticle ionic materials (G-NIM). G-NIM could be stably dispersed in abroad spectrum of solvents at a super-high concentration of500mg/ml.(4) A kind of bio-based polyester (BE) was synthesized by poly-condensation betweenplant-derived diols and diacids. The individually dispersed GO sheets in DMF were obtainedby the solvent-exchange method. BE was then grafted onto GO via the easterification, whichwas then subjected to reduction by vitamin C. In the BE/graphene composites, graphenesheets were interconnected by the BE chains, which favored the formation of conductivepaths at very low graphene loading. The concurrently increased electrical and thermalconductivity were a consequence of well-dispersion of graphene in BE and the interconnectedstructure of graphene.(5) Graphene oxide was directly reduced into graphene in N-methyl-pyrrolidone with theassisted-dispersion of vapor grown carbon nanofibers (VGCF), resulting in a homogeneousdispersion of VGCF-graphene (VGCF-G) hybrid filler. In the hybrid filler, VGCF served aseffective stabilizers for graphene by adsorbing VGCF onto graphene through π-π interactionbetween them. The obtained hybrid filler was incorporated into a bio-based polyester (BE) toprepare BE/VGCF-G composites. In the BE/VGCF-G composites, the dispersion of VGCFand interfacial adhesion between BE and VGCF were greatly improved because that theincorporated graphene acted as “compatibilizer” between VGCF and BE, leading tosignificant synergistic effects in improving the electrical conductivity and mechanicalproperties of the composites. Furthermore, multi-stimuli responsive shape memory performances (electro-activated and infrared-triggered) of the composites were investigated,and it was showed that BE/VGCF-G composites had a combination of higher shape memoryrecovery, stronger recovery stress and faster response, compared with the compositescontaining VGCF alone.(6) Tannic acid functionalized graphene (TAG) aqueous dispersion was prepared andused to hybridize with tubular clay, halloysite nanotubes (HNTs), to prepare a hybrid colloid(HNTs-TAG). The driving force for the hybridization was disclosed to be the specificinteractions (hydrogen bond and bridged bidentate bond) between the catechols on TAG andalumina/siloxane surfaces of HNTs. The obtained hybrid colloid was then co-coagulated withstyrene-butadiene rubber (SBR) emulsion to prepare elastomeric composites. Results showedthat a3D hybrid filler network consisting of HNTs and TAG was developed and served as anovel networked reinforcement in the SBR matrix. The formed hybrid filler network, togetherwith the enhanced interfacial adhesion, was considered to be responsible for the extraordinarysynergetic effects on improving the modulus and strength of the composites.更多还原