【作者】 熊芸；

【导师】 杨亚江；

【作者基本信息】 华中科技大学 ， 高分子化学与物理， 2008， 博士

【摘要】 小分子凝胶剂(LMOGs)通过非共价键(例如分子间氢键、π-π堆砌、范德华力、配位作用等)在溶剂中自组装形成纤维状、棒状、管状、盘状、带状、螺旋状等形貌的超分子聚集体结构,进而相互缠绕形成三维网络结构禁锢溶剂分子形成稳定的超分子凝胶(也称为“物理凝胶”),这一研究领域近年来受到了广泛的关注。超分子凝胶因其特殊的热可逆性、环境敏感性和纳米结构的多样性,被广泛地应用于智能材料、药物载体、模板材料、凝胶电解液、手性分离和催化等领域。本文合成了三种不同烷基链长的二脲型凝胶剂,能够使某些有机溶剂在室温下即可发生凝胶化,研究了它们在有机溶剂中的凝胶化能力和自组装机理,探讨了所形成的超分子凝胶的热力学性质和流变学性质。以十八烷基链长的二脲型凝胶剂为模型分子,研究了离心力场和剪切力场作用对小分子凝胶剂在溶剂中组装形成的聚集体的形貌及热力学性能影响。开创性的将二脲型凝胶剂和酰胺类凝胶剂通过加热、超声的作用灌注到有机蒙脱土片层间,研究小分子凝胶剂在片层结构的纳米尺寸受限空间内的聚集组装。首次将凝胶超分子结构用于手性分离薄膜的制备,考察了制备的手性分离膜对D-和L-苯丙氨酸的吸附差别。本论文包括以下几方面内容:1、利用二异氰酸酯与烷基胺的高反应活性,以及产物所带的氢键作用位点和烷基疏水作用力,设计合成了能以极低浓度使多种有机溶剂在室温条件下凝胶化的三种二烷基脲型凝胶剂:1-甲基-2,4-二(N’-十八烷脲基)苯(简称MBB-18)、1-甲基-2,4-二(N’-十二烷脲基)苯(简称MBB-12)和1-甲基-2,4-二(N’-八烷脲基)苯(简称MBB-8)。研究了该类型的凝胶剂在有机溶剂中组装形成超分子凝胶的热力学性质和流变学性质。2、利用傅立叶红外吸收光谱(FT-IR)、核磁共振氢谱(1HNMR)和X射线衍射(XRD),结合Spartan、HyperChem等化学软件,研究了二烷基脲型凝胶剂在有机溶剂中的组装机理并模拟了分子聚集图,利用场发射扫描电镜(FE-SEM)和差示扫描量热仪(DSC)探讨了烷基链的不同对分子组装方式的影响和热力学性质的影响,简单讨论了溶剂作用对分子组装的影响。3、以MBB-18凝胶剂为模型分子,研究小分子凝胶剂在离心力场和剪切力场作用下的自组装。通过测定不同离心力大小作用下凝胶剂的最低凝胶化浓度研究外力作用对凝胶剂凝胶能力的影响;利用FE-SEM和XRD研究了外力作用对凝胶剂分子聚集过程的诱导作用,利用DSC研究了力场诱导下形成的聚集体的热力学性质。4、将不同烷基链长的二脲型凝胶剂MBB-18、MBB-12和酰胺类凝胶剂二(4’-硬脂酰胺苯基)甲烷(简称BSM-18)、二(4’-辛酰胺苯基)甲烷(BOM-8)通过加热、超声的作用灌注到层间距为2-3 nm的有机蒙脱土片层间,利用DSC研究小分子凝胶剂在片层结构的受限空间内形成的超分子凝胶的热力学性质,发现其相变温度远高于本体空间内形成超分子凝胶的相变温度,利用XRD结合分子模拟软件探讨了在片层结构的受限空间内凝胶剂可能采取的聚集方式。5、以Boc-L-苯丙氨酸为模板分子,利用MBB-18在丙烯酸酯类单体中形成的超分子凝胶结构制备手性分离薄膜,用于混旋苯丙氨酸的分离。通过紫外吸收光谱(UV)测定薄膜对D-和L-苯丙氨酸的吸附,利用正交表结合实验分析了凝胶剂浓度、模板分子浓度和单体配比对聚合物薄膜吸附效率的影响。更多还原

【Abstract】 Supramolecular gels (physical gels), formed by the low molecular mass organic gelators (LMOGs) self-assemble in organic solvents through the non-covalent bonds such as intermolecular hydrogen bonding,π-πstacking, van der Waals interactions, donor-acceptor interactions, coordination, solvophobic forces (hydrophobic forces for gels in water) and so on to form the supramolecular structure aggregates with fiber-like, rod-like, tube-like, disk-like, tape-like and other morphology, have generated enormous interest rencently for scientific research and application. Organogelators and their organogels have been used for smart materials, drug delivery systems, templates for nanomaterial preparation, gel electrolytes, chiral separation, catalysis other fields as a result of their thermo-reversibility, chemical sensitivity and diversity of nanostructures.Three kinds of reactable gelators with different alkyl chains were synthesized by using the high activity of isocyanate and alkylamine, and supramolecular gels could be obtained at room temperature. The thermodynamic properties and rheological behavior of gels and the mechanism of self-assembly were investigated. The effect of the centrifugal force field and shear field on morphology and thermodynamic properties of the supramolecular structure aggregates formed by gelator in solvents was investigated. We reported herein new aggregates of low molecular mass organic gelators confined within the nano-scale interlayer space of the mineral organo-montmorillonite (OMMT), the thermodynamic properties and the possible mechanism of self-assembly were studied.This thesis is consisted of several sections as the following:1 Three kinds of reactable gelators 1-methyl-2,4-bis(N’-octadecylureido)benzene (MBB-18), 1-methyl-2,4-bis(N’-dodecaneureido)benzene (MBB-12) and 1-methyl-2,4- bis(N’-octanaureido)benzene (MBB-8) were synthesized, which could aggregate and self-assembly at room temperature, and forming thermal reversible gels with several organic solvents at very low concentrations. The thermodynamic and rheological properties of the supramolecular gels were investigated.2 Field emission electron microscopy (FE-SEM) revealed a three-dimensional (3D) network consisting of fiber-like aggregates. Moreover, various lengths of alkyls led to different morphology of fiber-like aggregates and different thermodynamic properties as Differential scanning calorimetry (DSC) showed. FT-IR and 1HNMR demonstrated that intermolecular hydrogen bonding was the main driving force for the self-assembly and formation of the gels. Finally, a self-assembly mode was proposed through the results of X-ray diffraction (XRD) and molecular stimulation by Spartan and HyperChem software.3 The aggregates of MBB-18 occur under the influence of centrifugal force and shearing force fields was investigated. The minimum gelation concentrations of MBB-18 in organic solvents under a centrifugal force field were significantly higher than those in the absence of a centrifugal force field, indicating a significant effect of the external field on the self-assembly of MBB-18. The oriented aggregation of MBB-18 in solvents induced by centrifugal and shearing forces, as well as the thermotropic behavior of oriented organogels has been investigated by FE-SEM, XRD and DSC respectively.4 Two bisurea gelators MBB-18, MBB-12 and tow acylamide gelators bis(4’- stearamidophbeyl)methane (BSM-18) and bis(4’-octanamidophenyl)methane (BOM-8) were affused into the interlayers of organo-montmorillonite (OMMT) by heating and ultrasonication to investigate the gelation of chlorobenzene and poropylene carbonate (PC) confined within the nano-scale interlayer space. Based on an analysis of the DSC and XRD data for the gels confined within the organo-montmorillonite and formed in the bulk space, we argued that the gelators self-assembled in an unusual manner when confined within the interlayer space of OMMT in comparison with that in bulk space. This novel route for self-assembling of gelators in confined space might offer new insights into the mechanism of natural self-assembling processes, which occured in nano-scale environments.5 Chiral separation films were prepared through the supramolecular structure aggetates formed by MBB-18 in acrylate monomer using Boc-L-phenylalanine as template molecule for the separation of racemic phenylalanine. Adsorption efficiency of D- or L-phenylalanine on the films with different concentration of gelator and template molecule, and with different monomer ratio was carried out by the UV spectra.更多还原