摘 要

随着科学水平和技术的不断提高，人类对能源的需求和使用也日益增长，能源短缺的现象也愈发突出。居民生活水平不断提高，建筑的耗能也因为人们追求更舒适的居住环境也越来越高，因此建筑节能成为节能环节的重要一步。将具有超低导热系数的二氧化硅气凝胶运用于建筑外墙涂料，对于建筑节能具有重要的意义。而将二氧化硅气凝胶运用于建筑外墙涂料需要将二氧化硅气凝胶进行修饰和改性的研究，使其具有良好的分散性和憎水的特点。

本文在研究前期采用Stöber法制备了具有单分散性的二氧化硅气凝胶微球，并研究了氨水用量对于所制备微球微观形貌和尺寸的影响，采用SEM进行了表征，测出了部分微球的导热系数。在完成SiO₂气凝胶微球制备的基础上，进行了SiO₂气凝胶微球接枝改性和憎水改性的实验的研究。接枝改性采用的硅烷偶联剂为分散剂(30%m-PCE)，实验研究了分散剂的用量对接枝改性效果和微球在水与乙醇两种极性不同的溶剂分散性能的影响，并采用SEM，EDS，及激光粒度分析进行了表征，确定了合适的分散剂使用比例。憎水改性实验则采用了三甲基氯硅烷作为改性剂，并通过索氏提取器进行表面溶液的置换，使-（CH3）₃取代-OH形成疏水的伞狀，达到疏水的效果，通过SEM观察了改性后微球的形貌，并通过EDS对憎水改性反应进行的程度进行了分析。实验得出，随着氨水用量的增加微球平均尺寸增大，但氨水用量大于一定值时会影响微球的单分散性，导热系数也随着尺寸的增大而增大，分散剂占微球质量比例为2%时，即15g微球加入分散剂6.39g时，接枝改性程度高，且分散性最好。采用体积比为10：1的正己烷与三甲基氯硅烷混合溶液改性程度更好。

关键词；SiO₂气凝胶微球，Stöber法，接枝改性，憎水改性

Abstract

The energy crisis is becoming more prominent as our human beings’ demand for energy increases greatly due to the continuous development of science and technology.The large population of our country.as well as the improvment of our living standards have resulted the requirement of a more suitable living environment which makes the energy consumption of building grow rapidly,thus building energy conservation has become a vital step in energy conservation. While utilizing the silica aerogels with ultra-low thermal conductivity in the coatings for building facades is of great significance to energy conservation.However the silica aerogels requires to be modified to be highly dispersed and hydrophobic

During the early research of this paper,monodispersed silica nanospheres were prepared according to the Stöber Method ,and the impact of the amount of ammonia to the micromorphology and size of the silica nanospheres were studied.The silica nanospheres were characterized by SEM and its thermal conductivity is measured.Based on that,grafting modification and the hydrophobic modification research was conducted.The 30%m-PCE was employed as the dispersing agents in the grafting modification,and the impact of its amount to the dispersity of silica nanospheres in water and ethanol as well as the grafting result was studied. SEM,EDS and laser particle size analysis were taken to characterize the modified nanospheres.The appropriate proportion of dispersants was determined. In the hydrophobic modification ,TMCS was used as the modifier.And the replacement of the surface solution was conducted in a Soxhlet extractor, so that - (CH3) ₃ , the substituent of -OH can form a hydrophobic umbrella, to achieve the hydrophobic effect.SEM and EDS were used to characterize the modified nanospheres.The results of the experiment show as follow：the average microsphere size increases along the increase of the amount of ammonia, monodispersity of the microspheres will be disturbed when greater than a certain amount of ammonia, the thermal conductivity will increases with the increase of the microsphere’s size, when15g microspheres dispersant is added 30% -PCE 6.39g, a high degree of graft modification was gained and its dispersion was of the best.When using a mixed solution of trimethylsilyl chloride and n-hexane in the hydrophobic modification, A preferably monodisperse SiO₂ microspheres was received, and the volume ratio of 10: 1 of trimethylsilyl chloride and n-hexane, the highest degree of graft modification was get.

Key Words：SiO₂ aerogels nanospheres，Stöber Method，graft modification ，hydrophobic modification

摘 要 I

第一章 绪论 - 1 -

1.1背景和意义 - 1 -

1.2 SiO₂气凝胶的特征及发展 - 1 -

1.2.1 SiO₂气凝胶微的基本特征 - 1 -

1.2.2 SiO₂气凝胶的发展史 - 3 -

1.3气凝胶的热学特性及绝热领域的应用 - 4 -

1.4 SiO₂气凝胶的制备工艺研究现状 - 6 -

1.4.1溶胶-凝胶工艺过程 - 6 -

1.4.2 凝胶的老化 - 7 -

1.4. 3溶剂交换 - 8 -

1.4.4 疏水二氧化硅气凝胶与表面改性 - 8 -

1.4.5凝胶的干燥 - 9 -

1.5课题研究目的和意义 - 10 -

1.6 本文主要研究内容 - 10 -

1.6.1 SiO₂气凝胶微粒微球的制备与改性的研究 - 10 -

1.6.2 常压干燥制备SiO₂ 气凝胶微球的表征 - 10 -

第二章 实验试剂、仪器与方法 - 11 -

2.1 实验材料与主要仪器设备 - 11 -

2.1.1 实验原料及试剂 - 11 -

2.1.2 主要实验设备仪器 - 12 -

2.2 实验工艺路线 - 12 -

2.2.1 SiO₂微球的制备 - 12 -

2.2.2 SiO₂微球改性实验 - 13 -

2.3 性能表征 - 16 -

2.3.1 所制备微球的性能表征 - 16 -

2.3.2 改性后微球的性能表征 - 16 -

第三章 实验结果和分析 - 17 -

3.1 SiO₂气凝胶微球制备 - 17 -

3.1.1 Stöber法制备SiO₂气凝胶微球的SEM图像结果和分析 - 17 -

3.1.2 SiO₂微球导热系数结果和分析 - 20 -

3.2 SiO₂气凝胶微球接枝改性实验结果和分析 - 20 -

3.2.1 SEM测试结果分析 - 20 -

3.2.2 激光粒度分析实验结果和分析 - 21 -

3.2.3 EDS实验测试结果和分析 - 25 -

3.2.4 分散性实验 - 27 -

3.3憎水改性实验结果和分析 - 28 -

3.3.1憎水改性微球的SEM图像 - 28 -

3.3.2憎水改性微球的EDS分析 - 28 -

第四章 总结 - 30 -

参考文献 - 31 -

致 谢 - 33 -

第一章 绪论

1.1背景和意义

近几十年来，科学水平和技术不断提高，而能源结构没有得到良好改善。在步入21世纪后，全球经济飞速发展，使得能源短缺的现象也愈发突出，能源危机已然成为了一个全球性的问题。而解决能源危机的方法，一方面是加快对新能源的开发，而另一方面则是采用有效的的节能手段。如今，在我国建筑高能耗的问题也随着国民生活水平的提高也更加更加突出，寻找有效的建筑节能措施迫在眉睫。

除了建材生产的能耗外，房屋和建筑的耗能也因为人们追求更舒适的居住环境也越来越高^[1]。我国人口数量庞大，如果能降低建筑的耗能对我国的能源问题将起到重要的作用。而建筑外墙涂料作为一种有效的，直接的措置受到了广泛关注。

二氧化硅气凝胶是一种由纳米量级颗粒相互聚合形成的连续三维网络结构，孔隙中充满空气介质的高分散轻质多孔非晶态材料^[2]。二氧化硅气凝胶具有高比表面积，高孔隙率，高热绝缘性，低密度，超低介电常数以及低折射系数等优异性能，且性能可随着对结构的控制而具有连续可调性^[2]。因而，可以考虑将具有优异绝热性能的SiO₂气凝胶运用于建筑外墙涂料而使外墙具有绝热保温性能，该运用能显著减少墙体散热，调控室温，对于建筑节能具有重要的意义。此外，SiO₂气凝胶还能进行憎水改性等修饰。在进行疏水改性后，SiO₂气凝胶外墙涂料还能提高建筑的气密性和防水功能，延长建筑寿命，保证舒适的室内环境^[2]。