【作者】 徐壁；

【导师】 蔡再生；

【作者基本信息】 东华大学 ， 纺织化学与染整工程， 2010， 博士

【摘要】 随着社会的发展以及生活水平的提高,人们对多功能纺织品的需求愈来愈旺盛,而纳米技术的迅猛发展为纺织品的功能化提供了有利条件。其中,ZnO是一种重要的直接宽带隙半导体材料,一维纳米结构ZnO应用于纺织品整理可以赋予纺织品良好的抗紫外线、抗菌、自清洁等功能。SiO2气凝胶是一种由纳米SiO2颗粒相互连接形成三维网络骨架,并在网络孔隙中充满空气的轻质纳米固态材料。由于其独特的结构,SiO2气凝胶是目前世界上最好的隔热材料,应用SiO2气凝胶制备的纺织品具有绝佳的隔热阻燃效果。因此研究基于纳米结构ZnO、SiO2的功能纺织品及新型气凝胶中的制备和性能具有十分重要的科学价值和现实意义。本文正是围绕这一主题开展了一系列研究工作,主要的研究内容包括：(一)棉纤维表面ZnO纳米棒阵列的原位生长。利用水热法在覆盖有ZnO纳米晶种层的棉纤维表面竖直生长ZnO纳米棒阵列。探讨棉纤维表面ZnO纳米晶种层、水热反应溶液浓度、水热反应温度、水热反应时间对ZnO纳米棒阵列的制备与形貌结构的影响。研究表明：纤维表面的ZnO纳米晶种层是ZnO纳米棒阵列生长的前提和基础；通过调节水热反应条件可实现对ZnO纳米棒阵列形貌尺寸的控制；纤维表面生长有ZnO纳米棒阵列的棉织物具有超强的抗紫外线性能。(二)棉纤维表面微观粗糙结构的构筑与疏水性研究。利用SiO2纳米颗粒与ZnO纳米棒阵列在棉纤维表面构筑不同的微观粗糙结构,结合低表面能物质修饰成功制备超疏水棉织物。静态接触角和滚动角测试结果表明基于SiO2纳米颗粒构筑粗糙表面的棉织物具有更大的静态接触角,但纤维表面生长有ZnO纳米棒阵列的棉织物显示出更小的滚动角。我们认为,这主要和水滴与纤维表面接触时形成的固/液/气三相接触线有关,水滴与ZnO纳米棒阵列接触时更容易形成扭曲的、非连续性的固/液/气三相接触线,因而水滴更容易在其表面滚动。(三)柔性超疏水Si02气凝胶的常压干燥制备。以甲基三甲氧基硅烷(MTMS)作为反应前躯体,控制反应温度,常压干燥条件下制备SiO2气凝胶,制备过程避免传统常压干燥法制备SiO2气凝胶所需的溶剂置换、低表面能物质修饰等繁冗过程。研究表明：老化温度与凝胶化温度对SiO2气凝胶的制备具有重要影响。老化温度提高,SiO2醇凝胶网络进一步完善,网络骨架进一步增强,其抵御毛细管张力的能力增强,SiO2气凝胶体积收缩率与密度逐渐降低。凝胶化温度提高,凝胶网络内孔隙逐渐增大,通过调节凝胶化温度从而控制凝胶网络内孔隙结构可实现低密、低收缩SiO2气凝胶的制备。此外,制备的MTMS基SiO2气凝胶表现出良好的弹性和超疏水性能。(四)机械增强SiO2气凝胶的常压干燥制备。以MTMS和乙烯基三甲氧基硅烷(VTMS)作为共前躯体,常压干燥条件下制备SiO2气凝胶。研究表明：常压干燥过程中,孔隙结构是决定SiO2气凝胶形貌和性能的关键因素。如果凝胶网络比较致密,常压干燥过程中的毛细管效应比较显著,容易造成SiO2气凝胶的破裂。如果凝胶网络比较疏松,纳米颗粒团簇间的孔隙增大,降低毛细管效应在常压干燥过程中对凝胶网络的影响,有助于制备块状无碎裂的SiO2气凝胶；但过大的孔隙会降低纳米颗粒团簇间的连接密度,削弱SiO2气凝胶的物理机械性能,制备的SiO2气凝胶比较脆弱。前躯体浓度与凝胶化温度对凝胶网络的孔隙结构具有重要影响,因此控制前躯体浓度和凝胶化温度对SiO2气凝胶的制备十分重要。此外,MTMS/VTMS基SiO2气凝胶具有优良的弹性,在经受垂直方向多次重复压缩后几乎不发生收缩。为进一步改善SiO2气凝胶的物理机械性能,在MTMS/VTMS基SiO2溶胶中加入苯乙烯制备聚苯乙烯(PS)/SiO2杂化气凝胶。制备的PS/SiO2杂化气凝胶仍具有低密、高孔隙率的特点,但随着苯乙烯加入量的增多,纳米颗粒团簇变大,纳米颗粒间的部分孔隙被聚苯乙烯堵塞,导致PS/SiO2杂化气凝胶的比表面积逐步减少。红外光谱、核磁共振谱图表明PS成功沉积在凝胶网络内SiO2颗粒表面。压缩实验表明所制备的PS/SiO2杂化气凝胶具有良好的弹性,且杂化气凝胶的机械强度随着苯乙烯加入量的增多而迅速增大。此外,杂化气凝胶具有超疏水的特性。更多还原

【Abstract】 With the development of society and the improvement of standard living, people’s demands for multi-functional textiles have become increasingly stronger. The rapid development of nanotechnology provides advantageous conditions to the functionalization of textiles. ZnO is an important direct wide band gap semiconductor. Applying one dimensional nano-structured ZnO materials onto textiles can endow the textiles with UV-blocking, antimicrobial and self-cleaning properties. Furthermore, SiO2 aerogel is such a kind of solid materials which consists of SiO2 nanoparticles and has a continuous random network structure filling with gaseous dispersive medium. Due to its unique structure, SiO2 aerogel is currently the world’s best heat insulator. The textiles incorporated with SiO2 aerogel show excellent thermal insulation and inflame-retarding effects. Therefore, investigating the preparation and properties of functional textiles and novel aerogels based on nano-structured ZnO and SiO2 is very important. A series of studies have been carried out, and the major studies include:(1) In situ growth of ZnO nanorod arrays on cotton fibers.By hydrothermal method, oriented ZnO nanorod arrays were vertically grown onto the surface of cotton fibers which were precoated with layers of ZnO nanocrystals. The effects of the precoated ZnO nanocrystals, the concentration of the hydrothermal solution, hydrothermal temperature, hydrothermal reaction time on the preparation and morphology structure of ZnO nanorod arrays were investigated. The results show that the ZnO nanocrystals onto the cotton fibers are the prerequisite to ZnO nanorod growth. Morphology control of the ZnO nanorod arrays can be achieved by adjusting the hydrothermal reaction conditions. The grown ZnO nanorod arrays on cotton fibers endow the cotton fabrics with remarkable UV-blocking property.(2) The fabrication of microscale rough structures on cotton fibers and the corresponding superhydrophobicities.Different microscale rough structures were fabricated onto the surface of the cotton fibers by SiO2 nanoparticles and ZnO nanorod arrays. Then superhydrophobic cotton fabrics were prepared by subsequent modification with low surface energy material. Static contact angle and roll-off angle measurements show that SiO2 modified cotton fabric displays a higher contact angle while the ZnO modified cotton fabric shows a much smaller roll-off angle. It is believed by us that the difference in roll-off angle is related to the solid/liquid/gas three-phase contact line. Distorted and non-continuous solid/liquid/gas three-phase contact line is more easily formed for the ZnO modified cotton fabric when the water droplet contacts with the ZnO nanorod arrays, and therefore the water droplet is more easily to roll off from the ZnO modified cotton fabrics.(3) Preparation of elastic and superhydrophobic SiO2 aerogel by ambient pressure drying.Methyltrimethoxysilane (MTMS) derived aerogel was prepared by controlling the reaction temperatures via ambient pressure drying. Tedious solvent exchange and hydrophobic modification which are commonly used during SiO2 aerogel preparation by ambient pressure drying were avoided. The studies show that the ageing temperature and gelation temperature have great influences on the preparation of SiO2 aerogel. Increasing the ageing temperature will further improve the SiO2 alcogel network and strengthen the gel network skeleton, enhancing the resistance of gel network against capillary forces generated during the ambient pressure dyring and resulting in the decreased volume shrinkage and bulk density. Increasing the gelation temperature leads to larger pore sizes within gel network. Low density and low volume shrinkage SiO2 aerogel can be obtained by adjusting the gelation temperature and controlling the pore structure within the gel network. In addition, MTMS derived SiO2 aerogel shows excellent elasticity and superhydrophobicity.(4) Preparation of ambient pressure dried hybrid aerogel with enhanced mechanical property.Methyltrimethoxysilane (MTMS) and vinyltrimethoxysilane (VTMS) derived aerogel was prepared by ambient pressure drying. The studies show that the pore structure is the key factor in determining the morphology and properties of SiO2 aerogel by ambient pressure drying. If the gel network is dense, the capillary pressure effects during ambient pressure drying are more significant, leading to cracks. If the gel network is loose, the spaces between SiO2 clusters increase, reducing the impact of capillary effect on the gel network during ambient pressure drying. This is beneficial for the preparation of crack-free and monolithic SiO2 aerogel. However, too large pore sizes will decrease the overall connectivity of the SiO2 clusters, weakening the physical and mechanical properties of SiO2 aerogels and the prepared SiO2 aerogel is very fragile. The precursor concentration and gelation temperature have great influences on the pore structure of gel network. Therefore, adjusting the precursor concentration and gelation temperature is crucial for preparing SiO2 aerogel. In addition, MTMS/VTMS based SiO2 aerogel shows excellent elasticity and no obvious shrinkage was observed after repeated compression.To further improve the mechanical property of SiO2 aerogel, polystyrene (PS)/ SiO2 hybrid aerogel was prepared by adding styrene into the MTMS/VTMS derived alcosol. The prepared PS/SiO2 hybrid aerogels keep low bulk density and high porosity. The as-obtained hybrid aerogels show an increased cluster feature size and a decreased specific surface area with the increased volume of styrene. FTIR and solid state NMR spectra show that polystyrene was deposited onto the surface of the SiO2 particles within the gel network. The compression testing shows that the PS/SiO2 hybrid aerogel is elastic and the strength of the hybrid aerogel is drastically increased with the increase of the added styrene. Furthermore, the hybrid aerogel shows superhydrophobicity.更多还原