【作者】 马海红；

【导师】 史铁钧；

【作者基本信息】 合肥工业大学 ， 材料学， 2009， 博士

【摘要】 有机/无机杂化材料克服了单一材料和传统复合材料性能上的缺陷,它兼具有机材料的优点（如韧性、延展性和易加工性等）及无机材料的的优点（如刚性、高热稳定性和特殊的光电磁性能等）,因而其制备受到人们的广泛关注。有机/无机杂化纤维是有机/无机杂化材料中的一类,目前国内外对杂化纤维的研究报道较少,制备力学、热学及光学性能优良的杂化纤维的研究正逐步引起人们的关注。本论文用溶胶-凝胶法制备了多种SiO₂-TiO₂杂化纤维材料,研究了杂化和聚合机理、形貌、结构和性能。具体研究内容如下:1.以正硅酸乙酯（TEOS）为原料,采用溶胶-凝胶法制备了硅溶胶,探讨了影响硅溶胶可纺性的各种因素及制备SiO₂纤维的最佳反应条件,并采用FT-IR、光学显微镜及XRD等对SiO₂纤维结构和性能进行了分析。溶胶的可纺性受水硅摩尔比,酸硅摩尔比,催化剂种类及反应温度的影响。温度升高,溶胶的可纺性降低;使用HCl作催化剂,水硅摩尔比为1.5,酸硅摩尔比为0.03时溶胶的可纺性最好,所得SiO₂纤维为无定形,直径约为50μm,其透明度和均匀程度都比较好。研究内容为制备无定形SiO₂纤维和制备热学性能、光学性能改进的杂化纤维提供依据。2.以TEOS为原料,用溶胶-凝胶方法,在PMMA存在下制备了PMMA/SiO₂杂化纤维,并用原位聚合法制备了PBMA/SiO₂杂化纤维。通过FT-IR、SEM、TGA及DSC等分析手段,探索其杂化机理,研究两种杂化纤维的形貌、结构与性能。杂化纤维中,聚合物与SiO₂之间形成化学键;两种杂化纤维直径分别为160μm和80μm左右,有机无机相间形成均一的连续相,表面光滑,尺寸均匀,透明度较好;耐热性能均优于纯聚合物。PBMA/SiO₂杂化纤维具有更好的柔性。3.以TEOS和钛酸四丁酯（TBT）为前躯体,采用溶胶-凝胶法和提拉法制备了PMMA/SiO₂-TiO₂、PBMA/SiO₂-TiO₂杂化纤维。研究了它们的形貌、结构与性能,聚合物与SiO₂-TiO₂之间通过化学键连接;两种SiO₂-TiO₂杂化纤维的直径分别为150μm和50μm左右;有机无机相间形成均一的连续相;随TiO₂含量的增加,杂化纤维的紫外透过率不断降低,荧光发射峰的强度不断增加。TiO₂的引入使杂化纤维具有荧光发射性能,并对紫外线具有有效的屏蔽作用,减缓杂化材料的老化。研究结果对于研制开发新型光电纤维材料具有重要意义;同时为硅钛体系杂化纤维材料的制备提供了理论依据。杂化纤维的耐热性能优于纯聚合物的耐热性能。4.采用溶胶-凝胶原位聚合法和静电纺丝技术制备PBMA/SiO₂杂化电纺纤维,聚合物与SiO₂之间通过偶联剂（VTEOS）形成了共价键的连接;随聚合物含量的增加,电纺产物由直径为5μm左右的纤维变为堆聚在一起的表面光滑、大小不均的颗粒;与纯PBMA相比,杂化电纺纤维的热分解温度由260℃升高至348℃左右,热稳定性能优良。另外用静电纺丝技术制备PVA/SiO₂-TiO₂杂化电纺纤维,无机相（SiO₂-TiO₂）与PVA之间主要通过分子间羟基键合形成杂化;纤维直径为几百纳米。随（SiO₂-TiO₂）含量的增加,形成的网络结构增多,纤维的直径不断增加,并出现弯曲和扭曲现象,甚至有带状结构出现。杂化纤维中纳米TiO₂对紫外线的有效屏蔽,可以减慢PVA/SiO₂杂化材料的老化。与纯PVA纤维相比,杂化电纺纤维的结晶度明显降低,热分解温度由230℃升高至317℃左右,在酸性、中性和碱性条件下的疏水性和稳定性增强。5.以MMA、TBT为主要原料,采用溶胶-凝胶法制备了分散良好,无机相粒径为5nm左右的PMMA/TiO₂杂化材料。杂化材料中无机网络与高分子链之间以共价键相结合,相微区尺寸较小,有效的阻止了两相间的相分离;杂化材料以非晶态形式存在。随TiO₂含量的增加,杂化材料的无机相尺寸增大,透光度下降,紫外透过率不断降低。纳米TiO₂对紫外线的有效屏蔽,减缓了PMMA的光老化。与纯PMMA相比,PMMA/TiO₂杂化材料的热分解温度由270℃升高至300℃左右。应用纳米粒子对PMMA进行改性,从而扩大了PMMA的应用范围。研究结果为制备光学性能和热性能优良的杂化材料提供理论依据。更多还原

【Abstract】 Organic/inorganic hybrid materials combine the advantage of the organic materials （rigidity, high thermal stability and unique optical, electric and magnetie properties） and organic materials （toughness, ductility and processability）, which is different from the single marerials and conventional composite materials. So the preparation of such organic/inorganic hybrid materials has received great interest. Organic/inorganic hybrid fiber, which has received few researches at home and abroad, is a kind of organic/inorganic hybrid material. The preparation study of hybrid fibers with excellent mechanical, thermal and optical properties is of burgeoning interest. A variety of silicon-titania hybrid fiber materials with different organic substances were prepared by sol-gel method. Moreover, the hybrid and polymerization mechanisms, morphology, structure and properties of hybrid fiber materials were investigated. Main works are as follows:1. Silica sol was prepared by sol-gel method with tetraethoxysilane （TEOS） as the material. The influencing factors on the spinnability of silica sol and the best reaction conditions of the preparation of SiO₂ fibers were studied. The structures and properties of SiO₂ fibers were analyzed by FT-IR, optical microscope and X-ray diffraction. The spinnability of the sol influenced by the molar ratio of H+ and TEOS, the molar ratio of water and TEOS, the kind of the catalyst and the temperature of the reaction. The spinnability of the sol decreased with the increasing temperature. The sol possessed best spinnability when the molar ratio of water and TEOS is 1.5, the molar ratio of H+ and TEOS is 0.03 with HCl as catalyst. The SiO₂ fibers are amorphous fibers. The diameters of the fibers are about 50μm, and the fibers have good transparence and uniformity. This will provide the basis for the preparation of amorphous SiO₂ fibers and the hybrid fiber, which possessing improved thermal and optical properties.2. PMMA/SiO₂ hybrid fibers were prepared with PMMA existing and PBMA/SiO₂ hybrid fibers were prepared via in-situ polymerization with TEOS as material by sol-gel method. The mechanism of the hybrid reaction, the structures and properties of the two hybrid fibers were studied by FT-IR, SEM, TGA and DSC. In the hybrid fibers, polymer was linked with SiO₂ by chemical bonds. The diameters of the two hybrid fibers were about 160μm and 80μm, respectively. A homogeneous and continuous phase was formed between organic and inorganic phases. The hybrid fibers have smooth surface, uniform size and good transparence. They show better resistance to heat than pure polymer. PBMA/SiO₂ hybrid fibers have better flexibility.3. PMMA/SiO₂-TiO₂ and PBMA/SiO₂-TiO₂ hybrid fibers were prepared with TEOS and tetrabutyl titanate （TBT） as precursor by sol-gel and drawing method. The morphology, structure and property of hybrid fibers were studied. Polymer was linked with SiO₂-TiO₂ network by chemical bonds. The diameters of the two SiO₂-TiO₂ hybrid fibers were about 150μm and 50μm, respectively. A homogeneous and continuous phase was formed between organic and inorganic phases. With the increasing content of TiO₂, the Ultraviolet （UV） permeating ratio of the hybrid fibers decreased and the intensity of the fluorescene emission peak increased. With the introducing of titania, the hybrid fibers possess the fluorescene emission property and shield UV radiation effectively, which decrease the aging of the hybrid materials. The result of the study is significant to the research of new optical fiber materials and provide theory basis for SiO₂-TiO₂ hybrid fiber materials. The hybrid fibers show better resistance to heat than pure polymer.4. PBMA/SiO₂ hybrid electrospun fibers were prepared via sol-gel in-situ polymerization and electrospinning method. Polymer was linked with SiO₂ by covalent bond via coupling agent （VTEOS）. With the increasing content of polymer, the electrospun product changed from the hybrid fibers with the diameters of about 5μm to gathered smooth and heterogeneous granules. Comparing with pure PBMA, the hybrid fibers possess advantage thermal properties and the thermal decomposition temperature of that rises from 260 to 348℃.PVA/SiO₂-TiO₂ hybrid electrospun fibers were prepared by electrospinning method. PVA was linked with SiO₂-TiO₂ network by inter-molecular hydrogen bonds.The diameters of the electrospun fibers were hundreds nanometer. With the increasing content of SiO₂-TiO₂, the network structure increased; the diameter of the fibers increased gradually; blending and contorting structure existed and even ribbon structure appeared. The effective shielding to UV of nano-titania can decrease the aging of the PVA/SiO₂ hybrid materials. Comparing with pure PVA fibers, the crystallinity of hybrid electrospun fibers is decreased distinctly and the thermal decomposition temperature rises from 230 to 317℃. The stability and hydrophobicity of the hybrid fibers are both improved under different pH values.5. PMMA/TiO₂ hybrid materials, which were well-dispersed with inorganic size of 5nm, were prepared by sol-gel method with MMA and TBT as the main material. Polymer chains were linked with inorganic network by covalent bonds; the dimension of phase microdomain is small, which prevented the separation of the two-phase effectively. The hybrid materials existed in the amorphous form. With the increasing content of TiO₂, the dimension of inorganic phase increased, light transmission declined gradually and the transmission of UV reduced gradually. The effective shielding against ultraviolet rays of nanotitania can slow down the light aging of PMMA. Comparing with pure PMMA, the thermal decomposition temperature of PMMA/TiO₂ hybrid materials rises from 270 to about 300℃. PMMA was modified by nanometer particles and thus the scope of the application of PMMA was widened. This will provide the theoretical basis for the preparation of hybrid materials, which possessing improved optical and thermal properties.更多还原