竹材表面ZnO超疏水涂层的制备及表征

基于"荷叶效应"仿生原理,首先采用传统一步法和晶核辅助生长法合成ZnO纳米颗粒,再通过层层自组装法分别在竹材表面构建2种不同的微纳结构,并用低表面能物质十七氟癸基三甲氧基硅烷进行修饰,获得超疏水层,最后对其性能进行表征。扫描电子显微镜和原子力显微镜观察显示,传统一步法制备的ZnO纳米颗粒呈球形结构,粒径为200～400 nm,在竹材表面相对分散,粗糙度为18.6;而晶核辅助生长法制备的ZnO纳米颗粒呈纺锤形,粒径为100～300 nm,且具有明显的分层结构,粗糙度为28.9。水静态接触角测试结果显示,随着自组装次数增加,接触角先增加后减少,当自组装次数达到20次时,传统一步法和晶核辅助生长法制备的ZnO纳米颗粒构建的微纳层的水静态接触角达到最大值,分别为142.4°和152.4°,后者达到了超疏水的要求。酸碱试剂浸渍评价纳米颗粒的耐久性结果表明,2种方法制备的ZnO纳米颗粒在强酸强碱溶液中浸泡后,接触角均无明显变化,传统一步法制备的竹材接触角在pH 2的盐酸和pH 12的氢氧化钠溶液中分别浸渍12 h后,接触角仍保持在141.1°和141.7°;晶核辅助生长法制备的竹材在pH 2的盐酸和pH 12的氢氧化钠溶液中分别浸渍12 h后,接触角仍保持在150.2°和150.8°。耐磨性测试结果表明,2种方法制备的疏水竹材具有较好的耐磨性,在30cm的线性摩擦试验后,传统一步法制备的竹材接触角仍在142°左右,晶核辅助生长法制备的竹材接触角在150°左右。X射线衍射测试结果显示,2种方法制备的疏水涂层均具有明显的ZnO晶体的衍射特征峰。2种竹材样品在XRD曲线上均出现了32.45°,34.76°,36.82°和47.65°等一系列新衍射峰,而且这些衍射峰与标准的纤锌矿ZnO的XRD卡片(JCPDS,36-1451)一致。

Preparation and characteristics of super-hydrophobic layer of ZnO nanoparticles on bamboo surface

Based on the bionic principle of lotus effect, firstly, zinc oxide (ZnO) nanoparticles were synthesized by the traditional one-step method and crystal-assisted growth method, respecticely. Secondly, the superhydrophobic layers were constructed on bamboo surface by layer-by-layer method. Then, the microstructure, roughness, static contact angle and resistance of acid-base at room temperature of bamboo specimens were examined. The scanning electron microscope observation indicated that the ZnO nanoparticles prepared by the traditional one-step method showed a spherical structure with a diameter between 200 nm and 400 nm, while the ZnO nanoparticles fabricated by the crystal-assisted growth method showed a spindle-shaped structure with a diameter between 100 nm and 300 nm. The measurement of atomic force microscope indicated that the roughness of ZnO nanoparticle layer prepared by the traditional one-step method was 18.6, which was lower than that of the crystal-assisted growth method. The water static contact angle test results showed that the contact angle of bamboo firstly increased and then decreased with the number of self-assembly processes increased. When the number of self-assembly processes was 20, the static contact angles were up to the maximum. The contact angle of ZnO nanoparticle layer prepared by the traditional one-step method was about 142.4°, while the contact angle of ZnO nanoparticle layer prepared by the crystal-assisted growth method was around 152.4°, which reached the requirement of super-hydrophobicity. The contact angles after soaking in strong acid and alkali solution for 12 h had no significant changes, which meant that the two ZnO nanoparticle layers had strong resistance to acid and alkali. The contact angle of bamboo prepared by the traditional one-step method remained at 141.1° and 141.7°, while the other remained at 150.2° and 150.8°. The abrasion resistance test indicated that the super-hydrophobic bamboo prepared by the two methods had good wear resistance. The contact angle of bamboo prepared by the traditional one-step was still about 142° after 30 cm of linear friction experiment, while the contact angel of bamboo prepared by the crystal-assisted growth method was about 150°.The X-ray diffraction detection proved that the diffraction peaks of ZnO crystals existed on the ZnO nanoparticle layers prepared by both methods. The bamboo prepared by both methods showed a series of new diffraction peaks such as 32.45°, 34.76°, 36.82° and 47.65°,which were consistent with the XRD card of standard wurtzite ZnO (JCPDS, 36-1451).