Introduction 介绍

Environmental concerns regarding the use of fossil fuels are not a new subject and have triggered the investigation of alternative energy sources for many years. Solar energy has been the subject of great interest among renewable energies due to its abundance, accessibility, and technical development.1 However, photovoltaic systems are prone to dust accumulation and other pollutant matter, reducing light transmittance and power generation efficiency.2 Cleaning of photovoltaic modules mainly includes manual cleaning, mechanical dust removal, and electrostatic dust removal technologies. However, there are some drawbacks associated with these cleaning methods such as waste of manpower, excessive water consumption, damage to the photovoltaic modules, high costs, and low cleaning efficiency.3 Develo** strategies to clean these systems with minimum human intervention are crucial to get the maximum potential from the existing solar panels.4 Large-scale renewable energy systems are often used in places with severe climactic conditions, where they are subjected to negative temperatures. This is a problem because ice and snow accumulation on photovoltaic devices will also impair their power generation efficiency.5
关于使用化石燃料的环境问题并不是一个新话题,多年来已经引发了对替代能源的研究。由于其丰富性、可获取性和技术发展,太阳能一直是可再生能源中备受关注的主题。 1 然而,光伏系统容易产生灰尘等污染物堆积,降低透光率和发电效率。 2 光伏组件的清洁主要有人工清洁、机械除尘、静电除尘技术。然而,这些清洗方法存在浪费人力、耗水过多、损坏光伏组件、成本高、清洗效率低等缺点。 3 制定以最少的人为干预来清洁这些系统的策略对于充分发挥现有太阳能电池板的潜力至关重要。 4 大规模的可再生能源系统通常用于气候条件恶劣的地方,承受负温度。这是一个问题,因为光伏设备上的冰雪积聚也会损害其发电效率。 5

A promising approach to obtaining self-cleaning surfaces is the application of hydrophobic and superhydrophobic coatings.6 In these surfaces, the adhesive forces between water and solid are substantially reduced which will allow the dust and dirt contaminants to be repelled by sliding away or rolling off the particles from the surface.7 Furthermore, if water and wet snow can be readily repelled, ice formation can be avoided instead of sticking on the surface.8
获得自清洁表面的一种有前途的方法是应用疏水和超疏水涂层。 6 在这些表面中,水和固体之间的粘附力大大降低,这将使灰尘和污垢污染物通过从表面滑走或滚落的颗粒而被排斥。 7 此外,如果水和湿雪可以很容易地被排斥,则可以避免结冰而不是粘在表面上。 8

Superhydrophobicity has been inspired by Nature, and it can be created by a unique combination of two parameters: surface energy and micro/nanoscale surface roughness.9,10 Hydrophobicity and surface energy are inversely proportional to each other. The surface energy is defined by the chemical composition of a surface which will influence its wetting behavior.9,10 A standard protocol for reducing the surface energy has been the use of fluorinated-based compounds, due to their intrinsically low surface energy as a result of their nonpolar chemistries.11,21 zinc oxide,22 alumina23 and zirconia.24 Such nanostructures will generate the nano-level roughness and their surface energy can be further decreased by using low surface-free energy functionalizing agents such as long alkyl silanes.25
超疏水性的​​灵感来自于大自然,它可以通过两个参数的独特组合来创建:表面能和微/纳米级表面粗糙度。 9,10 疏水性和表面能彼此成反比。表面能由表面的化学成分定义,这会影响其润湿行为。 9,10 降低表面能的标准方案是使用氟化基化合物,因为它们的非极性化学性质导致其本质上具有较低的表面能。 11,21 氧化锌、 22 氧化铝 23 和氧化锆。 24 这种纳米结构会产生纳米级的粗糙度,并且通过使用低表面自由能功能化剂(例如长烷基硅烷)可以进一步降低其表面能。 25

Among the several options to create micro- and nanoscale roughness, silica nanoparticles are the most often reported due to their low toxicity, optical transparency, and ease of surface modification.26 For instance, Liu et al.27 reported a superhydrophobic and transparent surface coating antifogging for optical lenses, using layer-by-layer assembly deposition of polyelectrolytes and silica nanoparticles followed by a fluorination treatment. Luo et al. proposed a non-fluorinated dip-coating method to create a superhydrophobic coating with high transparency for photovoltaic glass covers.28 The approach comprised several steps: an antireflective layer was first formed with a pore-forming agent; this layer was then coated with a superhydrophobic silica layer; and finally immersed in hexamethyldisilazane. The film presented a water contact angle of 152° and an average light transmittance of approximately 94%. More recently, a non-fluorinated approach has been proposed by Wu et al. in which siloxane-containing acrylate copolymers and silica nanoparticles resulted in coatings with great superhydrophobicity (water contact angle of 162.2°) and high transparency (approximately 90.83% transmittance at 550 nm).29
在产生微米级和纳米级粗糙度的多种选择中,二氧化硅纳米颗粒因其低毒性、光学透明性和易于表面改性而最常被报道。 26 例如,刘等人。 27 报道了一种用于光学镜片的超疏水透明表面涂层防雾,采用聚电解质和二氧化硅纳米颗粒的逐层组装沉积,然后进行氟化处理。罗等人。提出了一种非氟化浸涂方法,为光伏玻璃盖板创建高透明度的超疏水涂层。 28 该方法包括几个步骤:首先用成孔剂形成抗反射层;然后将该层涂上超疏水二氧化硅层;最后浸入六甲基二硅氮烷中。该薄膜的水接触角为152°,平均透光率约为94%。最近,Wu 等人提出了一种非氟化方法。其中含硅氧烷的丙烯酸酯共聚物和二氧化硅纳米颗粒形成的涂层具有良好的超疏水性(水接触角为162.2°)和高透明度(550 nm处的透过率约为90.83%)。 29

Zinc oxide is another material that has been the subject of great interest for its ability to be grown in a wide range of nanomorphologies and different functional properties.30 Li et al. reported a Zn/ZnO superhydrophobic coating with pine needle-like structure which was finally modified by stearic acid. Coatings exhibited a water contact angle of 167° and superior corrosion resistance.31 Other zinc oxide nanomorphologies reported to prepare superhydrophobic surfaces also include nanoparticles,32 nanoflowers33 and nanorods.34
氧化锌是另一种备受关注的材料,因为它能够以各种纳米形态和不同的功能特性生长。 30 李等人。报道了一种具有松针状结构的 Zn/ZnO 超疏水涂层,最终用硬脂酸进行改性。涂层的水接触角为167°,具有优异的耐腐蚀性。 31 据报道可制备超疏水表面的其他氧化锌纳米形态还包括纳米颗粒、 32 纳米花 33 和纳米棒。 34

Despite the great number of reported strategies to prepare superhydrophobic surfaces, there is a limited number of available coating strategies in the market. Important challenges in the development of superhydrophobic coatings that need to be addressed are the use of more eco-friendly reagents and easily scale-up approaches, and their durability so they can withstand harsh environmental conditions and high transparency for the particular case of photovoltaic applications.26
尽管有大量报道的制备超疏水表面的策略,但市场上可用的涂层策略数量有限。开发超疏水涂层需要解决的重要挑战是使用更环保的试剂和易于扩大规模的方法,以及它们的耐久性,以便它们能够承受恶劣的环境条件和针对光伏应用特殊情况的高透明度。 26

In this study, simple and non-fluorinated coating strategies were prepared through the incorporation of materials with different morphologies and chemistries on a commercially available waterborne acrylic polymer. Materials investigated include synthesized silica nanoparticles, alumina nanofibers, zinc oxide with different morphologies and commercially available zirconia and fumed silica. Silica, alumina, and zirconia were modified with the non-fluorinated hexadecyltrimethoxy silane (HDMTS) to decrease their surface-free energy. Formulations were then applied using a Mayer rod on glass substrates, a well-established coating process used in the industry due to its structural simplicity and ease of scaling up.35
在这项研究中,通过在市售水性丙烯酸聚合物上掺入具有不同形态和化学性质的材料,制备了简单的非氟化涂层策略。研究的材料包括合成的二氧化硅纳米粒子、氧化铝纳米纤维、不同形态的氧化锌以及市售的氧化锆和气相二氧化硅。使用非氟化十六烷基三甲氧基硅烷 (HDMTS) 对二氧化硅、氧化铝和氧化锆进行改性,以降低其表面自由能。然后使用 Mayer 棒将配方涂覆在玻璃基板上,这是业界使用的一种成熟的涂层工艺,因为其结构简单且易于放大。 35

Materials and methods 材料和方法

Materials 材料

Tetraethyl orthosilicate (TEOS), cetrimonium chloride (CTAC, 25% in water solution), triethylamine (TEA), zinc nitrate hexahydrate (Zn(NO3)2.6H2O) were purchased from Sigma-Aldrich. Ammonium hydroxide (25% in water solution) and aluminum butoxide were purchased from Acros Organics. Toluene, tetrahydrofuran (THF), and ethyl acetate were purchased from Ficher Chemical. Fumed silica CAB-O-SIL TS-382 was kindly provided from CABOT. Zirconia was purchased from Saint-Gobain. Hexadecyltrimethoxy silane (HDMTS) was kindly provided by Wacker. The self-crosslinking acrylic dispersion Alberdingk AC2403 was kindly provided by Alberdingk. The additive Aquaslip 671 was kindly provided by Lubrizol. Glasses (100 × 100 mm2) with a thickness of 3 mm were purchased from Vidraria Santa Cruz (Braga, Portugal). All the reagents were analytical grade and used as received without any further purification.
原硅酸四乙酯 (TEOS)、西三甲基氯化铵(CTAC,25% 水溶液)、三乙胺 (TEA)、六水合硝酸锌 (Zn(NO 3 ) 2 .6H 2 O) 购自 Sigma-Aldrich。氢氧化铵(25% 水溶液)和丁醇铝购自 Acros Organics。甲苯、四氢呋喃(THF)和乙酸乙酯购自Ficher Chemical。气相二氧化硅 CAB-O-SIL TS-382 由 CABOT 友情提供。氧化锆购自圣戈班。十六烷基三甲氧基硅烷 (HDMTS) 由瓦克友情提供。自交联丙烯酸分散体 Alberdingk AC2403 由 Alberdingk 友情提供。添加剂 Aquaslip 671 由路博润友情提供。厚度为 3 mm 的玻璃(100 × 100 mm 2 )购自 Vidraria Santa Cruz(葡萄牙布拉加)。所有试剂均为分析纯,按原样使用,无需任何进一步纯化。

Materials synthesis and chemical modifications

Silica nanoparticle synthesis and HDTMS modification

In the first step, 64 mL of deionized water was mixed with absolute ethanol (10.5 mL) and CTAC (10.4 mL) and stirred for 5 min at room temperature. Then, 4.1 mL of TEA was added to this solution, which was stirred for an additional 5 min. Next, 60 mL of this solution was heated at 60°C, and 4.35 mL of TEOS was then drop-wise added with a syringe. The reaction was kept at 60°C, under reflux for 2 h. The reaction was stopped by adding ethanol. Silica nanoparticles were separated by centrifugation at 4400 rpm, for 15 min, and washed three times with ethanol. Finally, they were dried overnight at 80°C.
第一步,将 64 mL 去离子水与无水乙醇 (10.5 mL) 和 CTAC (10.4 mL) 混合,并在室温下搅拌 5 分钟。然后,将 4.1 mL TEA 添加到该溶液中,再搅拌 5 分钟。接下来,将 60 mL 该溶液加热至 60°C,然后用注射器滴加 4.35 mL TEOS。将反应保持在60°C、回流下2小时。通过添加乙醇终止反应。通过以 4400 rpm 离心 15 分钟分离二氧化硅纳米粒子,并用乙醇洗涤 3 次。最后,将它们在 80°C 下干燥过夜。

Modification of silica nanoparticles with HDTMS was performed using two different procedures. HDTMS (3 mL) was added during synthesis for in situ modification, namely drop-wise added simultaneously with TEOS. For ex situ modification, 3 g of silica nanoparticles were dispersed in 150 mL of toluene, and this solution was heated at 60°C. HDTMS (3 mL) was then added drop-wise with a syringe and the reaction was kept at 60°C, under reflux, for 2 h and with constant agitation. Silica nanoparticles modified with HDTMS were washed and dried as aforementioned. These samples were designated as SiO2 in/ex situ HDMTS.
使用两种不同的程序用 HDTMS 对二氧化硅纳米颗粒进行改性。在合成过程中添加HDTMS (3 mL)进行原位修饰,即与TEOS同时滴加。对于异位改性,将 3 g 二氧化硅纳米颗粒分散在 150 mL 甲苯中,并将该溶液在 60°C 下加热。然后用注射器滴加HDTMS (3 mL),并将反应混合物在回流下保持在60°C 2小时并持续搅拌。用HDTMS改性的二氧化硅纳米颗粒按照前述进行洗涤和干燥。这些样品被指定为 SiO 2 in/ex situ HDMTS。

Alumina synthesis and HDMTS modification

Alumina nanostructures were prepared using a facile template-free thermal reaction previously described.36 Briefly, 20 g of water and an organic solution comprised of 20 g of aluminum butoxide in 20 g of toluene were put separately in different Teflon-lined chambers within one steel-lined autoclave. Thermal reaction was kept at 110°C so the water and organic phases diffused and encountered at an interface area. Alumina nanostructures obtained were finally obtained through calcination under 600°C.
使用先前描述的简单的无模板热反应制备氧化铝纳米结构。 36 简而言之,将20克水和由20克丁醇铝在20克甲苯中组成的有机溶液分别放入一个钢衬高压釜内的不同聚四氟乙烯衬里室中。热反应保持在110°C,因此水相和有机相扩散并在界面区域相遇。所得到的氧化铝纳米结构最终通过600℃的煅烧获得。

Alumina modification with HDTMS was performed as described for ex situ modification of silica nanoparticles. These samples were designated as Al2O3 ex situ HDMTS.
按照二氧化硅纳米粒子的非原位改性所述的方法用 HDTMS 进行氧化铝改性。这些样品被指定为 Al 2 O 3 非原位 HDMTS。

Zirconia modification with HDTMS
使用 HDTMS 进行氧化锆改性

Zirconia modification with HDTMS was performed as described for ex situ modification of silica nanoparticles and alumina. These samples were designated as ZrO2 ex situ HDMTS.
按照二氧化硅纳米粒子和氧化铝的异位改性所述的方法,用 HDTMS 进行氧化锆改性。这些样品被指定为 ZrO 2 非原位 HDMTS。

Zinc oxide microstructures synthesis

Zinc oxide with needle-like structures was prepared as previously described by using the precursor zinc nitrate hexahydrate.37 Ammonium hydroxide was added to a water solution of 0.05 M of Zn(NO3)2.6H2O until a pH of 10 was reached. The mixture was kept under reflux at 95°C for 5 h, without agitation. The precipitate was then filtered, washed several times with water and finally dried at 80°C, overnight. These samples were designated by needle-like ZnO. A prism-like structure was also prepared by adding a step to the previous procedure which was based on previous work.16 After reaching the pH of 10, the solution was stirred for 2 h at room temperature before being subjected to reflux at 95°C for 3 h, without agitation. These samples were designated by prism-like ZnO.
如前所述,使用前体六水合硝酸锌制备具有针状结构的氧化锌。 37 将氢氧化铵添加到 0.05 M Zn(NO 3 ) 2 .6H 2 O 的水溶液中,直至 pH 值达到达到了10个。将混合物在95℃下保持回流5小时,不搅拌。然后过滤沉淀物,用水洗涤数次,最后在80℃下干燥过夜。这些样品被命名为针状 ZnO。还通过在基于先前工作的先前程序中添加一个步骤来制备棱柱状结构。 16 pH达到10后,将溶液在室温下搅拌2小时,然后在95℃下不搅拌地回流3小时。这些样品被命名为棱柱状 ZnO。

Materials characterization

Fourier transform infrared (FTIR) spectroscopy
傅里叶变换红外 (FTIR) 光谱

Chemical modifications were evaluated by FTIR analysis. The spectra of materials were recorded with a Bruker FTIR VERTEX 80/80v (Boston, USA) in Attenuated Total Reflectance mode (ATR) with a platinum crystal accessory in the wavenumber range: 4000–400 cm-1, using 16 scans at a resolution of 4 cm-1. Before analysis, an open bean background spectrum was recorded as a blank.
通过 FTIR 分析评估化学修饰。使用 Bruker FTIR VERTEX 80/80v(美国波士顿)在衰减全反射模式 (ATR) 下记录材料的光谱,并使用波数范围为 4000–400 cm -1 的铂晶体附件,使用16 次扫描,分辨率为 4 厘米 -1 。在分析之前,将开放豆背景光谱记录为空白。

X-ray diffraction (XRD) analysis
X 射线衍射 (XRD) 分析

The phase composition of ZnO microstructures was determined using XRD on an X’Pert PRO diffractometer (PANanalytical) equipped with Ni-filtered Cu Kα radiation and a PIXcel detector. Data was collected using Bragg-Brentano geometry in a 2θ range from 20° to 80°. The XRD patterns were matched to the International Center for Diffraction Data (ICDD) PDF-4 database using the HighScore software package (PANalytical).
ZnO 微观结构的相组成是在配备 Ni 过滤的 Cu K α 辐射和 PIXcel 检测器的 X’Pert PRO 衍射仪 (PANanalytical) 上使用 XRD 测定的。使用 Bragg-Brentano 几何形状在 20° 至 80° 的 2θ 范围内收集数据。使用 HighScore 软件包 (PANalytical) 将 XRD 图案与国际衍射数据中心 (ICDD) PDF-4 数据库进行匹配。

Materials morphology 材料形貌

Materials morphology was observed using scanning electron microscopy (SEM) with an accelerating voltage of 15 kV (Quanta FEG 650, FEI, USA). Before analysis, samples were mounted on aluminum stubs using carbon adhesive tape and sputter-coated with gold.
使用加速电压为 15 kV 的扫描电子显微镜 (SEM)(Quanta FEG 650,FEI,美国)观察材料形态。在分析之前,使用碳胶带将样品安装在铝棒上,并溅射镀金。

Coatings preparation 涂料制备

Before coatings application, glasses were washed with a commercial detergent to remove impurities and grease, followed by rinsing with deionized water and isopropanol. Cleaned glasses were then dried using compressed air and further subjected to oxygen plasma cleaning for 10 min. As schematically shown in Fig. 1, materials were dispersed on the acrylic dispersion AC2403 at 2% (w/w) and these formulations were stirred for at least 24 h, at room temperature. Each formulation was further mixed using a homogenizer (Homogenizer M, VWR) for a few seconds and then used to coat the glass substrates using a Mayer bar with a wet thickness of 24 μm. Coatings were cured at 80°C for 24 h and left at room temperature for 7 days.
在涂覆涂层之前,用商业洗涤剂清洗玻璃以去除杂质和油脂,然后用去离子水和异丙醇冲洗。然后使用压缩空气干燥清洁的玻璃并进一步进行氧等离子体清洁10分钟。如图 1 示意性所示,材料以 2% (w/w) 分散在丙烯酸分散体 AC2403 上,并将这些制剂在室温下搅拌至少 24 小时。使用均质器(Homogenizer M,VWR)进一步混合每种配方几秒钟,然后使用湿厚度为 24 μm 的 Mayer 棒涂覆玻璃基材。涂层在 80°C 下固化 24 小时,并在室温下放置 7 天。

Fig. 1 图。1
figure 1

Schematic representation of the coating process

Coatings characterization

Hydrophobic properties were determined by measuring the static water contact angle, using a sessile drop method, in an automated contact angle measurement apparatus (DSA 100, Kruss) that allows image acquisition and data analysis. Contact angles were measured using 8 μL drops of deionized water. The total surface energy of coatings was calculated from the contact angle values of water and diiodomethane, as previously reported.38,39
通过在允许图像采集和数据分析的自动接触角测量装置(DSA 100,Kruss)中使用固滴法测量静态水接触角来确定疏水性。使用 8 μL 去离子水滴测量接触角。如先前报道的,涂层的总表面能是根据水和二碘甲烷的接触角值计算的。 38,39

Coatings morphology was evaluated by SEM and their surface roughness was determined with the Elcometer 7062 surface roughness tester.
通过SEM评估涂层形貌,并使用Elcometer 7062表面粗糙度测试仪测定其表面粗糙度。

The ability to prevent ice formation was evaluated by measuring the time a 10 µL droplet of deionized water took to freeze on coated surfaces, using a homemade setup. For that, substrates were kept at − 20°C for 1 and 6 h and after this period, they were placed on top of a frozen surface to keep their low temperature. A droplet was added on top of each surface, and the time needed to freeze was recorded for a maximum of 10 min.
通过使用自制装置测量 10 µL 去离子水滴在涂层表面上冻结所需的时间来评估防止结冰的能力。为此,将基材在 - 20°C 下保持 1 和 6 小时,在此期间后,将它们放置在冷冻表面的顶部以保持低温。在每个表面顶部添加一滴液滴,记录最多 10 分钟的冻结时间。

The transmittance spectra were obtained on a Lambda 950 UV–VIS NIR (PerkinElmer) in the wavelength range of 400–900 nm.
透射率光谱是在 Lambda 950 UV-VIS NIR (PerkinElmer) 上获得的,波长范围为 400-900 nm。

Self-cleaning behavior was determined by leaning the coated glasses in a Petri dish and using sand as an artificial contaminant.

The chemical stability of coatings was evaluated by a spot test in which droplets of different chemicals were placed on top of them for 24 h at room temperature. Chemicals tested include ethanol, ethyl acetate, THF and an aqueous solution with a pH adjusted to 5.6 to simulate acid rain.
涂层的化学稳定性通过点测试进行评估,其中将不同化学品的液滴在室温下置于其顶部 24 小时。测试的化学品包括乙醇、乙酸乙酯、THF 和 pH 值调整至 5.6 以模拟酸雨的水溶液。

Coatings adhesion to the glass was evaluated by a tape peeling test performed based on the standard ASTM D3359. In this test, the adhesion is evaluated by applying and removing pressure-sensitive tape over cuts previously made in the coating. This test was done before and after immersion of the coatings in water at 40°C for 3 days.
涂层对玻璃的附着力通过基于标准 ASTM D3359 进行的胶带剥离测试来评估。在此测试中,通过在涂层中先前制作的切口上施加和去除压敏胶带来评估粘附力。该测试是在将涂层浸入 40°C 水中 3 天之前和之后进行的。

Statistical analysis 统计分析

Statistical analysis and graphs were performed using the Origin data analysis and graphing software (Origin version 9.0). Means and standard deviations were calculated, and statistical analysis was carried out by one-way ANOVA followed by Tukey’s multiple comparisons, and \(p\) values < 0.05 were considered significant.
使用 Origin 数据分析和绘图软件(Origin 版本 9.0)进行统计分析和绘图。计算平均值和标准差,并通过单向方差分析和 Tukey 多重比较进行统计分析,p 值 < 0.05 被认为是显着的。

Results and discussion 结果与讨论

Materials characterization

As an alternative to the use of fluorinated compounds, HDMTS, a silane coupling agent was used in this study to impart silica, zirconia, and alumina with hydrophobic properties. Chemical modifications were investigated by ATR-FTIR and the results are shown in Fig. 2.
作为氟化化合物 HDMTS 的替代品,本研究中使用了一种硅烷偶联剂,赋予二氧化硅、氧化锆和氧化铝疏水性。通过ATR-FTIR对化学修饰进行了研究,结果如图2所示。

Fig. 2 图2
figure 2

Materials characterization: ATR-FTIR spectra of silica (a), zirconia (b) and alumina (c) before and after HDMTS modification; XRD pattern of needle-like (d) and prism-like zinc oxide (e)
材料表征:HDMTS 改性前后二氧化硅 (a)、氧化锆 (b) 和氧化铝 (c) 的 ATR-FTIR 光谱;针状氧化锌 (d) 和棱柱状氧化锌 (e) 的 XRD 图

Results showed that all silica spectra (Fig. 2a) before and after in/ex situ modification with HDMTS have absorption peaks at 791 and 1032 cm-1, which may be attributed to the antisymmetric and symmetric contraction vibration peaks of the Si–O–Si bond.25,40 At about 950 cm-1, there is a small absorption peak in the spectrum of unmodified silica, which can be assigned to the stretching vibration of Si–OH on the surface of silica nanoparticles. Unmodified silica also presents two absorption peaks at 2852 e 2923 cm-1, representing the stretching vibrations of –CH2 and –CH3 bonds,41 respectively, which are an indication that CTAC, the template used during silica synthesis was not completely removed.42,43 After chemical modification with HDMTS, the absorption peaks in these two places were stronger, especially for the silica-modified in situ, suggesting that the long-chain hydrophobic alkyl groups of HDMTS were successfully grated on the surface of silica nanoparticles.
结果表明,HDMTS原位/异位改性前后的所有二氧化硅光谱(图2a)均在791和1032 cm处有吸收峰 -1 ,这可能归因于二氧化硅的反对称和对称收缩振动峰。 Si-O-Si 键。 25,40 在约 950 cm -1 处,未改性二氧化硅的光谱中有一个小的吸收峰,这可以归因于二氧化硅纳米颗粒表面 Si-OH 的伸缩振动。未改性的二氧化硅还在 2852 e 2923 cm -1 处呈现两个吸收峰,代表 –CH 2 和 –CH 3 键的伸缩振动, 41 HDMTS化学修饰后,这两个地方的吸收峰更强,特别是原位修饰的二氧化硅,表明HDMTS的长链疏水烷基成功地磨在了表面。二氧化硅纳米颗粒。

In the spectra of zirconia before and after HDMTS modification (Fig. 2b), it is possible to identify the presence of an absorption peak at about 566 cm-1, which has been attributed to the vibrational stretch of the Zr–O bond.44 The successful modification of zirconia with HDMTS was suggested by the presence of three new absorption peaks at about 1467, 2857 and 2919 cm-1, corresponding to the stretching vibrations of C–O, –CH2 and –CH3 bonds, respectively.
在HDMTS改性前后的氧化锆光谱中(图2b),可以识别出在约566 cm -1 处存在吸收峰,这归因于Zr的振动拉伸–O 键。 44 在 1467、2857 和 2919 cm 处出现三个新的吸收峰,表明 HDMTS 成功修饰了氧化锆 -1 ,对应于 C-O 的伸缩振动,分别为 –CH 2 和 –CH 3 键。

Similar results were obtained after HDMTS modification of alumina (Fig. 2c). Both spectra have an absorption peak at about 761 cm-1 which can be attributed to the Al–O bond.45 HDMTS modification was suggested by the appearance of the absorption peaks corresponding to the stretching vibrations of –CH2 and CH3.
对氧化铝进行 HDMTS 改性后也得到了类似的结果(图 2c)。两个光谱在约 761 cm -1 处都有一个吸收峰,该吸收峰可归因于 Al-O 键。 45 HDMTS 修饰通过对应于 –CH 2 和 CH 3 伸缩振动的吸收峰的出现表明。

In recent years, the development of superhydrophobic surfaces just by controlling the micro/nano-roughness without the need for any additional modification step has been the subject of great interest.46 For this reason, zinc oxide with needle-like and prism-like structures was also investigated in this study. The crystal structure of synthesized zinc oxide with needle-like structures was determined by XRD analysis (Fig. 2d), and the XRD pattern obtained was consistent with the compound being ZnO (zincite, ICDD no. 96-900-8878). Regarding the prism-like structures (Fig. 2e), the XRD pattern was consistent with the compound being mostly Zn(OH)2 (wulfingite, ICDD no. 96-101-1224).
近年来,仅通过控制微/纳米粗糙度而不需要任何额外的修饰步骤来开发超疏水表面已引起人们极大的兴趣。 46 为此,本研究还研究了具有针状和棱柱状结构的氧化锌。通过X射线衍射分析确定了合成的针状结构氧化锌的晶体结构(图2d),获得的X射线衍射图谱与化合物为ZnO(红锌矿,ICDD号96-900-8878)一致。关于棱柱状结构(图2e),XRD图谱与主要为Zn(OH) 2 的化合物一致(红铝锌矿,ICDD no. 96-101-1224)。

The morphology of all materials investigated in this study is shown in Fig. 3. Results showed that silica nanoparticles (Figs. 3a, b) exhibit a spherical shape with a diameter of around 700 nm. Images also suggest that the presence of HDMTS during the synthesis of silica results in fewer particles agglomeration as opposed to their ex situ modification. Both modified zirconia (Fig. 3c) and alumina (Fig. 3d) presented a more complex and no structured morphology. The commercial fumed silica (Fig. 3e) also investigated in this study consists of fractal-like aggregates of nanoparticles as previously described.47 Zinc oxide can exhibit a needle-like structure (Fig. 3f) with a variable length between 2 and 5 µm or a prism-like structure (Fig. 3g) with a variable length in the microscale (6–9 µm).
本研究中研究的所有材料的形貌如图 3 所示。结果表明,二氧化硅纳米颗粒(图 3a、b)呈球形,直径约为 700 nm。图像还表明,与非原位改性相比,在二氧化硅合成过程中 HDMTS 的存在会导致更少的颗粒团聚。改性氧化锆(图3c)和氧化铝(图3d)都呈现出更复杂且无结构的形态。本研究还研究了商业气相二氧化硅(图 3e),它由纳米颗粒的分形聚集体组成,如前所述。 47 氧化锌可以呈现出长度在 2 至 5 µm 之间可变的针状结构(图 3f)或在微米尺度(6 –9 微米)。

Fig. 3 图3
figure 3

SEM images of silica-modified in situ with HDMTS (a), silica-modified ex situ with HDMTS (b), zirconia modified ex situ with HDMTS (c), alumina modified ex situ with HDMTS (d), fumed silica (e), needle-like (f) and prism-like (g) zinc oxide
用 HDMTS 原位改性的二氧化硅 (a)、用 HDMTS 异位改性的二氧化硅 (b)、用 HDMTS 异位改性的氧化锆 (c)、用 HDMTS 异位改性的氧化铝 (d)、气相二氧化硅 (e) 的 SEM 图像、针状 (f) 和棱柱状 (g) 氧化锌

Coatings characterization

The wettability of a surface can be controlled by two major factors: surface chemistry and surface roughness. In terms of chemistry, HDMTS was used to provide functional moieties with low surface energy and subsequently more hydrophobic.25 To create the surface roughness, materials with different morphologies were incorporated into the acrylic dispersion. The hydrophobic properties of the coatings prepared were evaluated by measuring the static water contact angle, and results are shown in Fig. 4.
表面的润湿性可以通过两个主要因素控制:表面化学和表面粗糙度。在化学方面,HDMTS 用于提供具有低表面能和随后更加疏水的功能部分。 25 为了产生表面粗糙度,将具有不同形态的材料加入到丙烯酸分散体中。通过测量静态水接触角来评价所制备涂层的疏水性能,结果如图4所示。

Fig. 4 图4
figure 4

Water contact angle of glass before and after application of different coatings. Significant differences were found for (*) p < 0.05, compared to glass and (#) p < 0.05, compared to AC2403 controls
施加不同涂层之前和之后的玻璃的水接触角。与玻璃相比,(*) p < 0.05 存在显着差异;与 AC2403 对照相比,(#) p < 0.05 存在显着差异

Results showed that the hydrophilic glass could be imparted with hydrophobic features just by the application of the acrylic dispersion AC2403, as evidenced by the water contact angle of approximately 106°. Incorporation of both modified silica, fumed silica, needle-like and prims-like zinc oxide resulted in an increase in the water contact angle and the maximum value of about 118° was reached for the needle-like zinc oxide coating. Zirconia and alumina were not able to confer more hydrophobic properties than the ones imparted by the acrylic dispersion alone. Results confirm, therefore, that the incorporation of materials with a more controlled morphology is an advantage to create hydrophobic surfaces.
结果表明,仅通过丙烯酸分散体AC2403的应用就可以赋予亲水玻璃疏水特性,水接触角约为106°。改性二氧化硅、气相二氧化硅、针状和初级状氧化锌的加入导致了水接触角的增加,并且针状氧化锌涂层达到了约 118° 的最大值。氧化锆和氧化铝不能赋予比单独丙烯酸分散体赋予的疏水性更多的疏水性。因此,结果证实,加入具有更受控形态的材料有利于创建疏水表面。

To complement these data, the surface-free energy was also determined based on the contact angles of water and diiodomethane and results are presented in Table 1.
为了补充这些数据,还根据水和二碘甲烷的接触角确定了表面自由能,结果列于表 1。

Table 1 Surface-free energy determined of glass before and after application of different coatings
表1 玻璃涂覆不同涂层前后的表面自由能测定

Results showed that the surface energy of glass could be significantly decreased just by the application of the acrylic dispersion. The incorporation of fumed silica and both zinc oxide morphologies on this dispersion resulted in a decrease in this parameter, especially the needle-like zinc oxide, achieving the lowest value of free energy. Comparing these data with the water contact angles in Fig. 4, it is possible to conclude that results agree with a theory which states that surface-free energy and hydrophobicity are inversely proportional to each other.10
结果表明,仅通过丙烯酸分散体的应用就可以显着降低玻璃的表面能。在该分散体中加入气相二氧化硅和两种氧化锌形态导致该参数下降,特别是针状氧化锌,实现了最低的自由能值。将这些数据与图 4 中的水接触角进行比较,可以得出结论,结果与表面自由能和疏水性彼此成反比的理论一致。 10

To better understand the hydrophobic properties exhibited by the different coatings, their surface morphology was evaluated by SEM and results obtained are presented in Fig. 5.
为了更好地了解不同涂层表现出的疏水性能,通过 SEM 评估了它们的表面形态,所得结果如图 5 所示。

Fig. 5 图5
figure 5

SEM images of glass after being coated with AC2403 before (a) and after incorporation of silica-modified in situ with HDMTS (b), silica-modified ex situ with HDMTS (c), zirconia modified ex situ with HDMTS (d), alumina modified ex situ with HDMTS (e), fumed silica (f), needle-like (g) and prism-like (h) zinc oxide
玻璃在涂覆 AC2403 之前 (a) 和掺入 HDMTS 原位改性二氧化硅 (b)、HDMTS 异位改性二氧化硅 (c)、HDMTS 异位改性氧化锆 (d)、氧化铝之后的 SEM 图像使用 HDMTS (e)、气相二氧化硅 (f)、针状 (g) 和棱柱状 (h) 异位改性氧化锌

Results showed that glass coated with only AC2403 (Fig. 5a) exhibited a homogenous and smooth morphology while the incorporation of the different materials caused significant changes in the surface morphology. In all the coatings with materials incorporated, it was possible to observe the presence of microcracks. Usually, these defects are caused by the evaporation of solvents during the curing process.48 However, if that was the case, they should also be present in the AC2403 coating as they were subjected to the same curing process. The defects observed were, therefore, attributed to the incorporation of the materials. Results suggest that coatings with silica-modified in situ with HDMTS (Fig. 5b), alumina modified ex situ with HDMTS (Fig. 5e) and fumed silica (Fig. 5f) present a similar morphology. The morphology of coatings with silica-modified ex situ with HDMTS (Fig. 5c) is similar but has fewer defects throughout the surface. The incorporation of zirconia modified ex situ with HDMTS (Fig. 5d) resulted in deeper cracks. A different morphology was presented by the coatings with needle-like (Fig. 5g) and prism-like (Fig. 5h) zinc oxide. Some materials agglomeration can also be observed on the higher magnitude inset pictures.
结果表明,仅涂有 AC2403 的玻璃(图 5a)表现出均匀且光滑的形态,而不同材料的加入导致了表面形态的显着变化。在所有含有材料的涂层中,可以观察到微裂纹的存在。通常,这些缺陷是由于固化过程中溶剂的蒸发造成的。 48 然而,如果是这样的话,它们也应该存在于 AC2403 涂层中,因为它们经历了相同的固化过程。因此,观察到的缺陷归因于材料的掺入。结果表明,用 HDMTS 原位改性二氧化硅的涂层(图 5b)、用 HDMTS 异位改性的氧化铝涂层(图 5e)和气相二氧化硅涂层(图 5f)呈现相似的形态。用 HDMTS 异位二氧化硅改性的涂层的形态(图 5c)相似,但整个表面的缺陷较少。将异位改性氧化锆与 HDMTS 结合(图 5d)会产生更深的裂纹。针状(图5g)和棱柱状(图5h)氧化锌涂层呈现出不同的形态。在更高级别的插图上也可以观察到一些材料的聚集。

Surface roughness is a critical factor in the development of hydrophobic surfaces. To evaluate this parameter a surface roughness tester was used to measure the roughness over a specified distance, recording peak-to-valley average. The average roughness determined for each coating is presented in Fig. 6.
表面粗糙度是疏水表面发展的关键因素。为了评估该参数,使用表面粗糙度测试仪测量指定距离上的粗糙度,记录峰谷平均值。每个涂层的平均粗糙度如图 6 所示。

Fig. 6 图6
figure 6

Average roughness of glass after application of different coatings. Significant differences were found for (*) p < 0.05 compared to AC2403 control
应用不同涂层后玻璃的平均粗糙度。与 AC2403 对照相比,(*) p < 0.05 存在显着差异

Results showed that the incorporation of the following materials increased the surface roughness of the polymer coating: silica-modified in/ex situ with HDMTS, fumed silica, needle-like and prism-like zinc oxide. These were the same materials able to increase the hydrophobic properties presented in Fig. 4, so there is a correlation between surface roughness increase and higher contact angle. However, the coating with the higher contact angle (needle-like zinc oxide) was not the coating with the highest values of roughness. Such results may be explained by the fact that the roughness measured using this equipment is within the microscale. However, it is well known that hydrophobicity is determined by the micro- and nano-roughness.
结果表明,以下材料的加入增加了聚合物涂层的表面粗糙度:用 HDMTS 进行原位/非原位改性的二氧化硅、气相二氧化硅、针状和棱柱状氧化锌。这些材料与图 4 所示的能够增加疏水性的材料相同,因此表面粗糙度的增加与较高的接触角之间存在相关性。然而,具有较高接触角的涂层(针状氧化锌)并不是具有最高粗糙度值的涂层。这样的结果可以用以下事实来解释:使用该设备测量的粗糙度处于微米级范围内。然而,众所周知,疏水性是由微米和纳米粗糙度决定的。

An important feature in the development of a coating strategy for photovoltaic systems is their ability to prevent ice formation, especially when these devices are placed in regions subjected to negative temperatures such as the desert. To investigate the anti-icing properties of the coatings, a simple setup was applied in which coated glasses were kept at − 20°C for different periods, and the time that a drop of water took to freeze on top of the coatings was then registered and the values obtained are presented in Table 2.
光伏系统涂层策略开发的一个重要特征是其防止结冰的能力,特别是当这些设备放置在沙漠等负温地区时。为了研究涂层的防冰性能,采用了一种简单的设置,将镀膜玻璃在 - 20°C 下保持不同的时间,然后记录一滴水在涂层顶部结冰所需的时间所得值如表 2 所示。

Table 2 The time (in seconds) that a drop of water took to freeze on glass before and after application of different coatings and after being at − 20°C for different periods: 1 h and overnight
表 2 施加不同涂层之前和之后以及在 - 20°C 下不同时间(1 小时和过夜)后,一滴水在玻璃上结冰所需的时间(以秒为单位)

Results showed that, in general, all coatings were able to delay ice formation, as compared to bare glass. The only exception was found for coatings with silica-modified ex situ. When the coatings were kept at − 20°C for 1 hour, the best anti-icing properties were exhibited by the formulations with silica nanoparticles modified in situ with HDMTS and zirconia modified ex situ with HDMTS. In these coatings, the droplet of water could never freeze. Coatings with alumina were also able to significantly delay ice formation while coatings with fumed silica, needle-like and prism-like zinc oxide presented anti-icing properties similar to the bare glass. Increasing the time during which the coatings were kept at − 20°C compromised their ability to delay ice formation, as compared to when they were subjected to negative temperatures for a shorter period. These results suggest that coatings will exhibit better anti-icing features if placed in regions with temperatures higher than − 20°C. Results showed, however, that coatings with silica nanoparticles modified in situ with HDMTS and alumina modified ex situ with HDMTS could significantly delay ice formation after being kept at − 20°C overnight. A possible explanation for this performance may be attributed to the similar morphology of these coatings as suggested by the SEM micrographs (Fig. 5).
结果表明,总体而言,与裸露玻璃相比,所有涂层都能够延迟结冰。唯一的例外是异位二氧化硅改性的涂层。当涂层在− 20°C下保持1小时时,用HDMTS原位改性二氧化硅纳米颗粒和用HDMTS异位改性氧化锆的配方表现出最好的防冰性能。在这些涂层中,水滴永远不会结冰。氧化铝涂层还能够显着延迟结冰,而气相二氧化硅、针状和棱柱状氧化锌涂层则具有与裸露玻璃类似的防冰性能。与短时间处于负温度下相比,增加涂层在− 20°C 下保持的时间会损害其延迟结冰的能力。这些结果表明,如果放置在温度高于 - 20°C 的区域,涂层将表现出更好的防冰特性。然而,结果表明,用 HDMTS 原位改性的二氧化硅纳米粒子和用 HDMTS 异位改性的氧化铝的涂层在 - 20°C 下保存过夜后可以显着延迟冰的形成。对于这种性能的可能解释可能是由于这些涂层的形态相似,如 SEM 显微照片所示(图 5)。

Previous studies have also used the delay time of water droplets to determine the anti-icing properties of coatings. For instance, Liu et al. prepared a superhydrophobic fluorinated coating which exhibited a delay time of 551 seconds at − 20°C.21 The conditions used to perform these studies are, however, different, so we cannot compare the delay time.
此前的研究也利用水滴的延迟时间来确定涂层的防冰性能。例如,刘等人。制备了超疏水氟化涂层,其在-20°C下的延迟时间为551秒。 21 然而,进行这些研究的条件不同,因此我们无法比较延迟时间。

It has been described that anti-icing properties are associated with hydrophobicity because hydrophobic surfaces will limit the amount of water available for nucleation and ice formation.8,49 However, results showed that coatings with higher water contact angles were not the ones with the best ability to prevent ice formation. Coatings with silica, zirconia and alumina were better than zinc oxide, the most hydrophobic one. Such results are corroborated by the ones reported by Zou et al. that concluded that a higher water contact angle is not necessarily good for preventing ice adhesion if the surface has high roughness.50 Other authors have also reported about the challenge of finding correlating surface parameters.51
据描述,防冰性能与疏水性相关,因为疏水性表面将限制可用于成核和冰形成的水量。 8,49 然而,结果表明,具有较高水接触角的涂层并不是具有最佳防止结冰能力的涂层。二氧化硅、氧化锆和氧化铝涂层比疏水性最强的氧化锌涂层更好。 Zou 等人报道的结果证实了此类结果。结论是,如果表面粗糙度较高,则较高的水接触角不一定有利于防止冰粘附。 50 其他作者也报告了寻找相关表面参数的挑战。 51

To ensure optimal power generation efficiency in photovoltaic systems, coatings application must not compromise the visible light transmittance of glass. For this reason, the UV–visible transmittance of coatings was determined, and the results are shown in Fig. 7.

Fig. 7 图7
figure 7

UV-visible transmittance spectra of glass before and after application of different coatings

Results showed that glass coated with the acrylic dispersion AC2403 was less transparent as evidenced by the slight decrease in the visible light transmittance. Further introduction of materials into this polymeric matrix led to a decrease in the visible light transmittance. The formulation with the best optical properties was the one with silica-modified ex situ with HDMTS. Fumed silica and alumina lead to a significant decrease in the visible light transmittance, but the worst performance was attributed to prism-like zinc oxide.
结果表明,涂​​有丙烯酸分散体AC2403的玻璃透明度较差,可见光透射率略有下降。进一步将材料引入该聚合物基质中导致可见光透射率降低。具有最佳光学性能的配方是用 HDMTS 进行二氧化硅非原位改性的配方。气相二氧化硅和氧化铝导致可见光透过率显着下降,但性能最差的是棱柱状氧化锌。

The challenges of poor durability and complex fabrication procedures associated with the development of coatings with both superhydrophobic and transparent features are well established.52 The high roughness required to create hydrophobic surfaces is the main cause of their opacity, and it can be explained by the Mie scattering effect. In this theory, surface roughness can be considered as non-absorbing spherical particles with the ability to deflect incident light, which results in a loss of transparency. The light transmittance of coatings will increase when the roughness dimension is much less than the wavelength of light. Light scattering is proportional to the square of the particle size, so, surfaces with a roughness lower than 100 nm are preferable to combine both transparency in the visible light and water-repellent features.53 Therefore, the decreased light transmittance of the prepared coatings in this study may be attributed to a higher roughness.
开发具有超疏水性和透明特性的涂层所面临的耐久性差和制造程序复杂的挑战是众所周知的。 52 创建疏水表面所需的高粗糙度是其不透明的主要原因,这可以通过米氏散射效应来解释。在该理论中,表面粗糙度可以被视为具有偏转入射光能力的非吸收性球形颗粒,从而导致透明度损失。当粗糙度尺寸远小于光的波长时,涂层的透光率会增加。光散射与粒径的平方成正比,因此,表面粗糙度低于100 nm更适合兼具可见光透明性和防水特性。 53 因此,本研究中制备的涂层的透光率降低可能归因于较高的粗糙度。

Another important feature associated with hydrophobic surfaces is their ability to easily clean dust and dirt particles. In these kinds of surfaces, because of the higher contact angle between the water and the surface, water droplets will readily roll off taking the dirt away.54 To evaluate the self-cleaning properties of prepared coatings, sand was used to simulate the contaminates and dyed colored water was then applied. Representative pictures taken during self-cleaning tests on the glass before and after coatings application are shown in Fig. 8.
与疏水表面相关的另一个重要特征是它们能够轻松清洁灰尘和污垢颗粒。在这些类型的表面中,由于水与表面之间的接触角较大,水滴很容易滚落,带走污垢。 54 为了评价所制备涂层的自清洁性能,使用沙子模拟污染物,然后涂上染色的有色水。图 8 显示了在涂覆涂层之前和之后对玻璃进行自清洁测试期间拍摄的代表性照片。

Fig. 8 图8
figure 8

Images of the self-cleaning experiments of bare glass (a, b) and coated glass (c, d)

It was observed that when the water was dropped on bare glass (Figs. 8a, b), the droplets readily infiltrated the contaminants and the contaminants mixed with the water remained on the surface. On the other hand, the contaminants on the coated glass (Fig. 8c, d) could be easily removed by rolling water and the washed area remained transparent, indicating the self-cleaning properties of the coating. All coating formulations prepared in this study exhibited these features.

A key aspect to consider in the development of any coating strategy is its adhesion to the substrate. A standard “scotch tape test” was carried out on the coated glasses to determine the adhesion of the coatings. In this test, adhesion is evaluated by applying and removing pressure-sensitive tape over cuts previously made in the coating. To also evaluate the robustness of the coatings, this test was performed before and after immersion of the coated glasses in hot water (40°C) for 3 days. Results were classified according to standard ASTM D3359 and are presented in Table 3.
制定任何涂层策略时要考虑的一个关键方面是其对基材的附着力。对镀膜玻璃进行标准“透明胶带测试”以确定涂层的附着力。在此测试中,通过在涂层中先前制作的切口上施加和去除压敏胶带来评估附着力。为了评估涂层的坚固性,在将涂层玻璃浸泡在热水(40°C)中 3 天之前和之后进行了该测试。结果根据 ASTM D3359 标准进行分类,如表 3 所示。

Table 3 Classification of the coating’s adhesion to glass based on ASTM D3359 before and after immersion in water at 40°C for 3 days
表 3 根据 ASTM D3359 在 40°C 水中浸泡 3 天之前和之后涂层对玻璃的附着力分级

Results showed that acrylic dispersion AC2403 by itself had good adhesion to the glass, as evidenced by the 5B classification. According to standard ASTM D3359, a classification of 5B means that the coating was not removed after applying the tape to the cut area. Further incorporation of materials into this polymeric matrix did not compromise its adhesion to the glass. All the coatings resisted the water immersion test, presenting the same classification, which is an indication of their durability and robustness.
结果表明,丙烯酸分散体 AC2403 本身对玻璃具有良好的附着力,正如 5B 分类所证明的那样。根据 ASTM D3359 标准,5B 级意味着将胶带粘贴到切割区域后涂层没有被去除。将材料进一步掺入该聚合物基质中并不会损害其与玻璃的粘附力。所有涂层都通过了水浸测试,呈现出相同的分类,这表明了它们的耐用性和坚固性。

The chemical resistance of prepared coatings was also evaluated to better predict their practical applicability. A solution with acid pH to represent the acid rain and three solvents (ethanol, ethyl acetate and THF) were applied on top of the coatings for 24 h and chemical resistance was evaluated as excellent (E) when no stains could be observed, good (G) when some light stains could be observed but the coating was not destroyed and not recommended (X) when the coating was destroyed. Results are presented in Table 4.
还评估了所制备涂层的耐化学性,以更好地预测其实际适用性。将代表酸雨的酸性 pH 溶液和三种溶剂(乙醇、乙酸乙酯和 THF)涂在涂层上 24 小时,当没有观察到污渍时,耐化学性评价为优秀(E),良好( G) 当可以观察到一些轻微污点但涂层没有被破坏并且不推荐时 (X) 当涂层被破坏时。结果如表 4 所示。

Table 4 Chemical resistance tests of coatings
表4 涂层耐化学药品性试验

It was possible to conclude that all coatings were able to resist the acid rain solution and ethanol, with no discoloration or loss of adhesion. Some discolouration could be observed on coatings exposed to ethyl acetate. The most aggressive chemical was THF, as evidenced by the loss of adhesion caused on all coatings except for the acrylic dispersion AC24023 and the coatings with needle-like and prism-like zinc oxide which only showed some discoloration. Such results may be attributed to the higher polarity of THF, as compared to the other solvents.
可以得出结论,所有涂层都能够抵抗酸雨溶液和乙醇,不会变色或失去附着力。在暴露于乙酸乙酯的涂层上可以观察到一些变色。最具腐蚀性的化学物质是 THF,除了丙烯酸分散体 AC24023 以及针状和棱柱状氧化锌涂层(仅表现出一些变色)外,所有涂层均造成附着力损失,这证明了这一点。与其他溶剂相比,这样的结果可能归因于 THF 的极性较高。

Conclusions 结论

In this work, materials with different morphologies were incorporated into a commercially available acrylic dispersion to create hydrophobic surfaces using a simple and non-fluorinated coating strategy for glass substrates.

Results showed that materials with a more controlled morphology (spherical shape of silica nanoparticles, needle-like and prism-like zinc oxide) were the best ones to impart the glass with hydrophobic features. All coatings exhibited self-cleaning properties and good adhesion to the glass substrate. Coatings application compromised the visible light transmittance of bare glass. Coatings comprising silica nanoparticles, zirconia and alumina modified with HDMTS were the best at preventing ice formation. In terms of chemical stability, all the coatings resisted acidic conditions close to acid rain pH and solvents with mild polarity. Further studies should be conducted toward increasing the coatings’ ability to transmit the visible light, by reducing the roughness without compromising their hydrophobic and self-cleaning features.
结果表明,形态更受控制的材料(球形二氧化硅纳米粒子、针状和棱柱状氧化锌)是赋予玻璃疏水特性的最佳材料。所有涂层均表现出自清洁性能以及对玻璃基材的良好附着力。涂层的应用损害了裸露玻璃的可见光透射率。由 HDMTS 改性的二氧化硅纳米粒子、氧化锆和氧化铝组成的涂层在防止冰形成方面效果最好。在化学稳定性方面,所有涂料都能抵抗接近酸雨pH值的酸性条件和弱极性溶剂。应该进行进一步的研究,通过降低粗糙度而不损害其疏水性和自清洁特性来提高涂层传输可见光的能力。