Room-Temperature Synthesis of Germanium Oxide Nanofilaments and Their Potential Use as Luminescent Self-Cleaning Surfaces

Germanium oxide nanofilaments (GNFs) have been synthesized under ambient conditions from the gas phase using germanium tetrachloride as a precursor. Non-crystalline GNFs synthesized by this procedure are 1–10 μm in length and 80–110 nm in diameter applying Droplet Assisted Growth and Shaping (DAGS) Chemistry. The relative humidity has been adjusted at various values in order to demonstrate the crucial role of humidity in the gas phase for the nanofilament synthesis. The novel GNFs show a strong luminescence emission in the ultra-violet and light blue region. In addition, a self-cleaning and superhydrophobic properties could be introduced in the luminescent GNF nanofilaments by simple treatment with silane molecules.     

基于无机纳米材料的抗菌抗病毒功能涂层和薄膜

COVID-19在全球的大流行对人类的健康生活和社会的正常运行都造成了严重的危害. 阻断致病微生物通过受污染表面与人类间接接触传播, 或者避免与其直接接触是保护我们免受伤害的主要方法. 目前的解决措施包括设计开发抗菌抗病毒表面涂层和研发由自清洁薄膜或织物制成的个人防护设备. 综述了近年来几种研究广泛的金属、金属氧化物、金属有机框架材料等用于抗菌抗病毒涂层或薄膜的工作, 对其作用机制和微生物灭活效果进行了总结讨论, 并且评估了其本身的毒性以及实际应用的局限性, 最后就抗菌抗病毒涂层和薄膜开发的挑战和新兴研究方向提出了未来展望.     

新型自然循环自动清洗式蒸发器及设计原理

以高效蒸发器为目标，旨在以自然循环替代高能耗的强制循环泵、以自动清洗取代加热面盐垢的周期性停车清洗．主要研究沸腾室内的不平衡汽化过程机理，提出动力温度的新概念，采用显热与汽化热转换平衡的研究方法，得到自然循环推动力的工程设计计算式，并且由此引出推动力强化的基本原则，进而获得中试的成功．还提出加热室必须采用能够低流速下自转清洗又高效传热强化的螺旋齿带，才能保障循环总阻力低于推动力．     

Cotton fabric coated with nano TiO2-acrylate copolymer for photocatalytic self-cleaning by in-situ suspension polymerization

Two kinds of nano TiO₂-polyacrylate hybrid dispersions, TBM-w and TBM-e were synthesized by in-situ suspension polymerization and solution polymerization respectively, in order to fix the nano TiO₂ on fabrics. The photocatalytic self-cleaning fabrics have received much attention in recent years for its water-saving and environment-protection advantages. However, the fixation of the photocatalyst on fabrics is still a key problem that inhibits industrialization of these eco-friendly fabrics. The cotton fabric was treated by the two hybrid dispersions. The photocatalytic self-cleaning property was characterized. Infrared spectroscopy, burning loss test and thermogravimetry showed that some copolymer chains entangled with the nano TiO₂. Transmission electron microscope illustrated that there was a polymeric layer on the surface of nano TiO₂. The average diameter of TBM-w was smaller than that of TBM-e based on size analysis. The photocatalytic decoloration of the grape syrup indicated that the fabric with TiO₂-polymer hybrid had excellent self-cleaning property.     

Photocatalytic Activity and Photo-Induced Wettability Conversion of TiO2 Thin Film Prepared by Sol-Gel Process on a Soda-Lime Glass

We have developed the transparent photoactive TiO₂ thin film coated on soda lime glass (SLG) by sol-gel process. Titanium dioxide thin films coated on SLG exhibit lower photocatalytic activity due to the thermal diffusion of Na ion from the SLG substrate. Thin SiO₂ film precoating is very effective to prevent the thermal diffusion of Na ion. We have evaluated the photocatalytic decomposition of gaseous acetaldehyde and the photo-induced surface wettability of TiO₂ films with and without SiO₂ precoating layer. As expected, the TiO₂ film on SiO₂/SLG is more photoactive to decompose acetaldehyde than that on SLG. However, as for wettability conversion, there was little difference in the conversion rate between TiO₂ film without SiO₂, and TiO₂ film with SiO₂. Different dependence of Na ion diffusion on two kinds of photo-induced reaction on TiO₂ is discussed based on the difference of the photo-induced reaction mechanism.     

Electrospun N‐Substituted Polyurethane Membranes with Self‐Healing Ability for Self‐Cleaning and Oil/Water Separation

Membranes with special functionalities, such as self‐cleaning, especially those for oil/water separation, have attracted much attention due to their wide applications. However, they are difficult to recycle and reuse after being damaged. Herein, we put forward a new N‐substituted polyurethane membrane concept with self‐healing ability to address this challenge. The membrane obtained by electrospinning has a self‐cleaning surface with an excellent self‐healing ability. Importantly, by tuning the membrane composition, the membrane exhibits different wettability for effective separation of oil/water mixtures and water‐in‐oil emulsions, whilst still displaying a self‐healing ability and durability against damage. To the best of our knowledge, this is the first report to demonstrate a self‐healing membrane for oil/water separation, which provides the fundamental research for the development of advanced oil/water separation materials.     

Counterion-Dictated Self-Cleaning Behavior of Polycation Coating upon Water Action: Macroscopic Dissection of Hydration of Anions

The counterions of polydiallyldimethylammonium (PDADMA) coatings were altered by incubation in aqueous solutions of different electrolytes. Oil de-wetting on the resulting polycationic surfaces upon water action exhibited a straightforward connection with the Jones–Dole viscosity B-coefficient (Bη) sign of surface counteranions. Upon water action, surface counteranions with negative Bη render PDADMA coatings oil-adhering, but those with positive Bη furnish PDADMA coatings with excellent self-cleaning. The oil-adhering PDADMA surfaces can become self-cleaning upon water action in response to the Bη of surface counteranions sign-switching with increasing water temperature. Courtesy of surface counter-anions with Bη>0, self-cleaning PDADMA coatings enable not only conversion of conventional meshes into self-cleaning membranes for oil/water separation, but also regioselective maneuver of oil flow on polycationic surfaces according to the Bη sign of surface counteranions patterned atop.     

微乳-水热法制备具有自清洁功能的TiO2薄膜

采用热陈化微乳液及浸渍-提拉技术,制备了具有自清洁功能的TiO2薄膜。考察了微乳液中表面活性剂十二烷基苯磺酸(DBS)的用量对TiO2薄膜的表面形态和微观结构的影响。进而对合成的TiO2薄膜的光催化活性、光致亲水性能及实际环境中的自清洁效果进行了测试评价。随着表面活性剂DBS用量的增加,微乳液中的分散质点尺寸减小,但热陈化后所获得的TiO2粒子表现出凝集现象。在DBS用量为0及58 mg/L时,所获得薄膜表面较为平整,由15～20 nm大小的TiO2粒子组成。这些薄膜在无紫外光照射时,水接触角增大的速度较慢,并且在紫外光照射下能迅速恢复其超亲水性能。将薄膜置于室外25 d后其表面无灰尘粘结,水接触角由原来的0°增大至14°～18°。当DBS用量为580 mg/L以上时,薄膜表面起伏不平,粗糙度过大,对应TiO2薄膜光致亲水性能较差,室外放置25 d后,水接触角由原来的0°增大至46°～48°。     

超亲水性SiO2-TiO2纳米颗粒阵列结构的制备与性能研究

用分子自组装的方法在玻璃衬底上分别制备了TiO₂纳米颗粒层和SiO₂-TiO₂复合纳米颗粒阵列结构. 其中,SiO₂ 纳米颗粒层用旋涂法制备,得到密排阵列结构,而TiO₂纳米颗粒层则用浸渍提拉法制备. 文章分析了TiO₂纳米颗粒层和SiO₂-TiO₂复合纳米颗粒阵列结构的理论粗糙度,并通过扫描电子显微镜研究了它们的微观结构,用接触角 关键词： 自清洁 表面粗糙度 光催化 分子自组装     

Biomimetic Self-Cleaning Anisotropic Solid Slippery Surface with Excellent Stability and Restoration

Anisotropic slippery surfaces are widely used in anti-fouling, smart control of liquid movement and directional liquid transportation. However, anisotropic slippery liquid-infused porous surfaces (SLIPS) cannot meet the need of practical applications owing to loss and contamination of liquid lubricants. Inspired by solid epicuticular wax on the surface of land plant leaves, we herein report a type of biomimetic anisotropic solid slippery surface (ASSS) based on paraffin wax-incorporated paper with directional micro-grooves. This ASSS material shows anisotropic sliding behavior for liquid droplets with different surface tensions. It is demonstrated to be of excellent stability compared with SLIPS as the solid lubricant cannot be lost and stain the contacting surfaces. It also exhibits outstanding acid and alkali corrosion resistance and restoration capability upon physical damage. Both hydrophilic and hydrophobic contaminants on our ASSS can be self-cleaned by using only water droplets. Our ASSS extends the fabrication of new slippery materials and overcomes some drawbacks of SLIPS.