论文总字数：25062字

摘 要

在炎热的夏季，太阳辐射较强，会透过建筑外墙、屋顶玻璃等导致室内温度升高，很多地区会使用降温设备，造成能源浪费。在寒冷的冬季，由于温度较低，外墙、玻璃表面的水雾易冻结，如车窗表面，给生活带来不便。因此在材料表面涂覆一层具有疏水性、防覆冰性、高反射率的降温涂层，可以减少能源的浪费同时为生活提供便捷。

聚甲基丙烯酸甲酯（PMMA）具有良好的透过率、韧性及耐热性等优良性能，可用于制备涂层。本实验首先采用硬脂酸对亚微米级二氧化钛（TiO₂）进行表面疏水改性，再将改性前后的TiO₂加入PMMA与丁腈橡胶（NBR）的复合基材中，制备一种具有疏水性、防覆冰性以及高太阳光反射性能的降温涂层。本次工作研究了TiO₂改性前后的表面疏水性、防覆冰性、光反射率及TiO₂表面改性对PMMA/NBR/TiO₂复合涂层的疏水性、防覆冰性、光反射率及降温性能的影响。

本实验采用接触角测定仪、傅里叶红外光谱仪、热重分析仪、紫外-可见-近红外分光光度计（UVPC）、太阳光模拟器等对材料进行测试和表征。实验结果表明未改性的TiO₂接触为27^o，而采用3 wt%硬脂酸改性后的TiO₂接触角达132^o，表现出优异的疏水性能。在-10 ^oC条件下，10 μL蒸馏水在未改性的TiO₂表面结晶时间为6 s，而在改性后的TiO₂表面延迟结晶时间为1284 s，可见疏水改性后的TiO₂具有优异的防覆冰性能而改性前后的TiO₂对太阳光的反射率变化不大，未改性的TiO₂在可见光和近红外的反射率分别为94.94%和74.17%，疏水改性后的TiO₂在可见光和近红外的反射率分别为89.87%和74.51%，均具有较高的反射率。

添加了TiO₂的PMMA/NBR/TiO₂复合涂层，在加入了疏水改性的TiO₂后，涂层表面的接触角和表面水珠的结晶时间都得到改善。PMMA/NBR涂层的接触角为112^o，添加50 wt%改性后TiO₂的复合涂层的接触角为118^o。PMMA/NBR涂层的延迟结晶时间为753 s，添加50 wt%改性后TiO₂的疏延迟结晶时间为1010 s，延迟了257 s。另外，TiO₂表面改性几乎不影响涂层的太阳光反射性能及降温效果，且涂层的太阳光反射性能随着TiO₂含量的增加而提高。PMMA/NBR涂层的反射率为14.1%，加入质量分数为50%的疏水改性的TiO₂后复合涂层的光反射率高达到76.61%，提高了62.51%。初始温度为24.3 ^oC、光强为0.3 W/cm²条件下光照1 h后，PMMA/NBR涂层的温度为41 ^oC，添加50 wt%的改性后的TiO₂的复合涂层的温度为27.4 ^oC，温度降低了13.6 ^oC。

关键词：TiO₂ PMMA 疏水改性 反射率 降温

Hydrophobic modification of TiO₂ surface and preparation of PMMA/TiO₂ functional coating

Abstract

In the hot summer, the sun's radiation is strong, and the temperature rises through the ordinary glass,Building exterior and roof. In many areas, cooling equipment is used, resulting in waste of energy. In the cold winter, due to the low temperature, the water mist on the surface of the glass is easy to freeze, such as the surface of the window, which brings inconvenience to life. Therefore, coating a surface of the glass with a hydrophobic, ice-repellent, and high-reflection coating can reduce energy waste while providing convenience for life.

Polymethyl methacrylate (PMMA) has excellent properties with good transmittance, toughness and heat resistance, which can be used to prepare coatings. In this experiment, the sub-micron titanium dioxide (TiO₂) was firstly hydrophobically modified with stearic acid, and the unmodified and modified TiO₂ was added to the composite substrate of PMMA and nitrile rubber (NBR) to prepare a hydrophobic and temperature-lowering coating that resists icing and high solar reflectance. In this study, the surface hydrophobicity, anti-icing property, light reflectance and surface modification of TiO₂ on the hydrophobicity, anti-icing property, light reflectance and cooling of PMMA/NBR/TiO₂ composite coating were studied.

In this experiment, the materials were tested and characterized by contact angle meter, Fourier infrared spectrometer, thermogravimetric analyzer, UV-Vis-NIR spectrophotometer (UVPC), and solar simulator. The experimental results show that the unmodified TiO₂ contact is 27^o, and the contact angle of TiO₂ modified with 3 wt% stearic acid is 132^o, showing excellent hydrophobic properties. Under the condition of -10 °C, the crystallization time of 10 μL distilled water on the surface of unmodified TiO₂ is 6s, and the delayed crystallization time of the modified TiO₂ surface is 1284 s. The hydrophobic titanium dioxide has good anti-icing performance. However, the reflectance of unmodified and modified TiO₂ did not change a lot. The reflectance of unmodified TiO₂ in visible light and near-infrared was 94.94% and 74.17%, respectively. The reflection of hydrophobically modified TiO₂ in visible and near-infrared The rates are 89.87% and 74.51%, respectively, both of which have higher reflectance.

The PMMA/NBR/TiO₂ composite coating with TiO₂ was added, and the contact angle of the coating surface and the crystallization time of the surface water beads were improved after the hydrophobically modified TiO₂ was added. The contact angle of the PMMA/NBR coating was 112^o, and the contact angle of the composite coating with 50 wt% modified TiO₂ was 118^o. The delayed crystallization time of the PMMA/NBR coating was 753 s, and the delayed crystallization time of the modified TiO₂ after adding 50 wt% was 1010 s, which was delayed by 257 s. In addition, the surface modification of TiO₂ hardly affects the solar light reflection performance and temperature drop effect of the coating, and the solar light reflection performance of the coating increases with the increase of TiO₂ content. The reflectivity of the PMMA/NBR coating was 14.1%, and the light reflectivity of the composite coating after the addition of the hydrophobically modified TiO₂ with a mass fraction of 50% reached 76.61%, an increase of 62.51%. After the initial temperature was 24.3 ^oC and the light intensity was 0.3 W/cm², the temperature of the PMMA/NBR coating was 41 ^oC, and the temperature of the composite coating of 50 wt% modified TiO₂ was 27.4 ^oC. The temperature is reduced by 13.6 ^oC.

Key words: TiO₂; PMMA; hydrophobic modification; reflectivity; cooling

目录

摘 要 I

Abstract III

第一章 绪论 1

1.1课题背景 1

1.2 国内外研究进展 1

1.2.1 TiO₂研究进展 1

1.2.2 PMMA研究进展 2

1.2.3 功能涂层研究进展 2

1.3 本课题的工作内容 3

1.4 TiO₂简介 3

1.5 PMMA简介 3

1.6 表面润湿机理 4

1.6.1 Young理论 4

1.6.2 Wenzel模型 4

1.6.3 Cassie-Baxter模型 5

1.6.4 表面疏水性影响因素 5

1.7 紫外屏蔽效应 5

1.8 光散射机理 6

第二章 实验部分 7

2.1 原材料 7

2.2 实验仪器与设备 7

2.3 实验配方 7

2.4 样品制备 8

2.5 测试表征 8

2.5.1 傅里叶红外光谱 8

2.5.2 热重分析仪 8

2.5.3 数码照片 8

2.5.4 接触角 9

2.5.5 防覆冰性能测试 9

2.5.6 紫外光-可见光-近红外分光光度计测试分析 9

2.5.7 降温性能 9

第三章 结果与讨论 10

3.1改性前后TiO₂粉体测试表征结果 10

3.1.1 傅里叶红外光谱测试 10

3.1.2 热重分析 11

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