【作者】 徐恒启；

【导师】 宋健；

【作者基本信息】 天津大学 ， 应用化学， 2012， 博士

【摘要】 本文建立了一种预测有机凝胶形成的简单模型，阐明了溶剂粘度、分子体积对MPBG（甲基-4,6-O-对氯苯亚甲基-α-D-吡喃葡萄糖苷，一个新型凝胶因子）自组装结构和凝胶性质的重要影响。将MPBG、膨胀石墨（EG）、1,3:2,4-二（3,4-二甲基亚苄基）-D-山梨醇（DMDBS）与三硬脂酸甘油酯（GT）结合，构建了一种新型复合定形储热相变材料（PCM2）。通过DSC、TG-DTA、FT-IR、SEM、TEM、XRD检测，研究了PCM2的储热性能和微观结构，揭示了凝胶因子对PCM2的定形机制。凝胶化检测研究揭示，Teas图可以用来预测有机凝胶的形成。使用4个未检测溶剂和8个文献报道的凝胶因子，验证了该方法。溶剂作用研究表明，在一元醇和芳香烃溶剂中，MPBG聚集体的形貌和影响凝胶性质的关键因素明显不同。SEM和XRD研究结果表明，在一元醇类溶剂中，MPBG分子自组装是溶剂粘度控制的扩散限制过程。进一步研究发现，尽管极性溶解度参数（δ_a）对凝胶因子聚集体形貌、凝胶相转变温度(T_gel)和凝胶数(N_gel)产生影响，但溶剂粘度是影响这些性质的关键因素。对于芳烃溶剂而言，δ_a是决定T_gel和N_gel的关键因素，但溶剂分子体积对它们也产生重要影响。在新型复合定形相变材料PCM2中，GT（86.6wt%）、EG（4.6wt%）分别用作储热和导热材料，作为支撑材料的凝胶因子（MPBG和DMDBS）起到定形作用。DSC结果显示，PCM2的熔点、熔化潜热分别为49℃和97J/g；凝固点、凝固潜热是46℃和69J/g。TG-DTA和FT-IR检测发现，在工作温度范围内，PCM2具有极佳的热稳定性和化学相容性（组份间）。SEM、TEM和FT-IR研究揭示，在PCM2中，凝胶因子MPBG和DMDBS自组装形成三维（3D）纤维网络，具有片层网络结构的EG被包埋于3D纤维网络之中。通过毛细管作用，3D网络束缚GT于其网孔之中，从而形成定形储热相变材料。XRD和FTIR研究表明，PCM2中的添加剂（EG、MPBG和DMDBS）并未影响GT的晶体结构，凝胶因子和EG的3D网络结构限制了GT分子热运动，从而导致PCM2相变焓的损失。更多还原

【Abstract】 This paper proposes a simple method for estimating organogel formation, andhighlights the important role played by solvent viscosity （η） and molecular size （V） ininfluencing the gel properties and the aggregate structures of methyl4,6-O-（p-chlorobenzylidene）-α-D-glucopyranoside （MPBG, a novel gelator） indifferent solvents. Furthermore, a novel form-stable composite phase change material（PCM2） was prepared by incorporating MPBG,1,3:2,4-di-（3,4-dimethyl） benzylidenesorbitol （DMDBS, a gelator） and expanded graphite （EG） into glyceryl tristearate （GT）matrix, and its thermal and structural characteristics were analyzed by DSC, TG-DTA,FT-IR, SEM, TEM and XRD. The form-stability mechanism of PCM2was alsorevealed.The research of gelation tests shows that Teas plot derived from solubilityparameters can be used to estimate the behaviour of a known gelator in untestedsolvents. The method has successfully been tested on the eight gelators reported inliteratures and the untested solvents in the gelation test of MPBG. The research ofsolvent role reveals that the aggregate morphologies of MPBG and the main factorsdetermining the gel properties are obviously different in the monohydric alcohols andthe aromatic hydrocarbons. According to SEM images and X-ray diffraction patterns,in monohydric alcohols with high viscosity value, the self-assembly of MPBG is adiffusion-limited aggregation process resulting from solvent viscosity. Furthermore, itis found that solvent viscosity, compared with the secondary role of polar solubilityparameter （δ_a）, plays a key role in determining the morphologies of aggregates, thesol-gel phase-transition temperature (T_gel) and the gelation number(N_gel). In contrast,for the aromatic hydrocarbon gels, solvent molecular size is very important indetermining T_geland N_gelalthough δ_ais the key factor.In PCM2, GT （86.6wt％） is used as the phase change material for thermalenergy storage, and EG （4.6wt%） acted as the thermal conductivity filler. In order toprevent the leakage of GT, gelators （MPBG and DMDBS）, as the supporting material,were added in the composite. The DSC results show that PCM2solidifies at46℃with a latent heat of69J/g and melts at49℃with a latent heat of97J/g when themass percentage of GT in the composite is86.6％. The TG-DTA and FT-IR resultssuggest that PCM2, in operating temperature range, exhibits good thermal stability and chemical compatibility（between the components of the composite）. According toSEM/TEM images and FT-IR spectroscopies, The MPBG and DMDBS molecules, inPCM2, self-assemble into nanofibers that form three-dimensional （3D） networksembedding EG with a3D lamellar network structure. By capillary and surface tensionforces, GT is retained in the pores of the3D networks, so leakage of the melted GTfrom PCM2is prevented. X-ray diffraction patterns and FT-IR data reveal thatadditives （MPBG, DMDBS and EG）in PCM2do not affect the crystal structure ofglyceryl tristearate, and the3D networks of gelators and EG confine the molecule heatmovement of GT in PCM2, which leads to the decrease in the latent heat of theform-stable composite phase change material.更多还原