【作者】 吕世昌；

【导师】 施文芳；

【作者基本信息】 中国科学技术大学 ， 高分子化学与物理， 2009， 博士

【摘要】 本论文采用离子交换法和共价接枝法改性蒙脱土和层状双氢氧化物,得到有机官能化的无机纳米粒子,有效地提高了其与聚合物基体的相容性;进一步采用紫外光辐照的方法制备了丙烯酸酯/蒙脱土纳米复合材料、丙烯酸酯/层状双氢氧化物纳米复合材料、环氧树脂/层状双氢氧化物纳米复合材料;所得复合材料在力学性能、物理性能和热稳定性等方面均得到明显提高。1.分别通过离子交换法和共价键接枝法以长链烷基季铵盐和含有丙烯酸酯基团的有机小分子改性钠基蒙脱土,从而提高了蒙脱土和丙烯酸酯低聚物的相容性。紫外光辐照使蒙脱土和聚合物基体通过共价键结合,获得丙烯酸酯/蒙脱土纳米复合材料,其力学性能和热稳定性均得到提高。当有机改性蒙脱土添加量为5 wt%时,固化膜的拉伸强度增加了11%,热降解温度(5 wt%失重)提高了23℃。2.通过共沉淀和离子交换法制备了长链烷基(DS)插层的层状双氢氧化物(MgAl(DS)-LDH),扩大了层间距并改善了层间化学环境;在紫外光辐照下被部分层离,获得插层/层离混合型聚合物/LDH纳米复合材料;相比未进行有机官能化的MgAl-LDH所得到的纳米复合材料形成更为均一和稳定的结构,而且固化膜的力学性能和热稳定性均得到了提高。3.为了改善双酚A环氧树脂的强度与柔韧性,以有机改性的MgAl(DS)-LDH作为增强剂,超支化环氧树脂E1作为增韧剂,发现前者在环氧树脂基体中得到层离,并分散均匀;在紫外光辐照下获得环氧树脂/层状双氢氧化物纳米复合材料,其固化膜的力学强度和热稳定性均得到提高,而且随其含量而变化;同时E1的加入进一步提高了材料的柔韧性。更多还原

【Abstract】 In recent years,ion-exchange process and covalent-graft method have been developed to organo-modify inorganic layerd materials,thus making them more organophilic and have better compability with polymer matrix.In this thesis,we demonstrated a novel method for the preparation of exfoliated nanocomposite based on the organo-modified clay with reactive acrylate group grafted to the clay layer by covalent bonds and also on organo-modified layered double hydroxide.The epoxy nanocomposites based on the ternary system of DGEBA,hyperbranched epoxy and LDH was also prepared.Furthermore,we aim to explore possible applications of these functionalized layered materials in high performance nanocomposites.1.The half adduct of isophorone diisocanate and 2-hydroxyethyl acrylate (IPDI-HEA),as a reactive organic modifier,was used to functionalize Na-montmorillonite(Na-MMT) clay.Unlike the electronic interaction in the conventional cation-exchange method,the driving force for the organic modification came from the chemical reaction between IPDI-HEA and framework hydroxyl groups on the surface of clay.With high degree of organic modification(48%),the d-spacing of clay layer was greatly enlarged to 3.32 nm,and the clay became more organophilic.After in situ photopolymerization among the IPDI-HEA grafted MMT clay,monomers and oligomers,the exfoliated polymer/clay nanocomposites were obtained. X-ray diffraction and transmission electron microscopy were used to detect the structure and morphology of the clay dispersed in the polymer matrix. Compared with the pure polymer materials,the exfoliated polymer/clay nanocomposites exhibited enhancements in mechanical and thermal properties.2.The thermal and mechanical properties of UV curing coatings consisted of urethane acrylates as an oligomer and a diacrylate monomer were reinforced by using layered double hydroxide(LDH).The LDH was organically modified by an ion-exchange process,in which the nitrate anions were replaced by long alkyl sulfate anions.With organic modification,the d-spacing of inorganic LDH layers was greatly enlarged to 2.75 nm from 0.78 nm,leading the LDH to be organophilic.During in situ photopolymerization process,the d-spacing of LDH layers was further enlarged to 4.29 nm,indicating the intercalation of polymer chains.For comparison,polymer/LDH nanocomposite filled with un-modified LDH was also prepared,and showed less enhancement in thermal and mechanical properties.3.The effects of organically modified layered double hydroxide(O-LDH) and epoxy functionalized hyperbranched aliphatic polyester(E1),on the mechanical strength,thermal property and toughness of diglycidyl ether of bisphenol A(DGEBA) epoxy resin were studied in details.The crystalline structure and morphology of the nanocomposites composed of DGEBA/O-LDH and DGEBA/E1/O-LDH were investigated by wide angle X-ray diffraction analysis and transmission electron microscopy observation. Both results showed that the LDH nanosheets were sufficiently exfoliated and randomly dispersed in the epoxy matrix.The thermal and mechanical properties were compared with the corresponding neat polymer matrix.The enhancement in strength and toughness was achieved by the addition of O-LDH and E1,respectively,and confirmed in terms of fracture surface analysis by scanning electron microscopy.更多还原