Superhydrophobic and transparent coatings prepared by self-assembly of dual-sized silica particles

Superhydrophobic and transparent coatings have been prepared by self-assembly of dual-sized silica particles from a mixed dispersion. The desirable micro/nano hierarchical structure for superhydrophobicity is constructed simply by adjusting the size and ratio of the dual-sized particles without organic/inorganic templates. The transparency of the prepared coatings is also researched, and the light scattering can be reduced by lowering the ratio of big sub-micro particles while the superhydrophobicity maintains unchanged. When nano particles with a diameter of 50 nm and sub-micro particles with a diameter of 350 nm are assembled, a superhydrophobic property with a water contact angle of 161° is achieved. Additionally, the coated glass is also very transparent. The highest transmittance of the coated glass can reach 85%. Compared to traditional colloid self-assembly approach, which often involves dozens of steps of layer-by-layer processing and organic/inorganic templates, the present approach is much simpler and has advantages for large-scale coating.     

单一粒径与两种粒径羰基铁粉磁流变液特性的实验比较研究

通过控制球磨时间,用球磨机球磨出不同粒径的羰基铁粉,制得单一粒径磁流变液8组和两种粒径磁流变液6组。采用旋转流变仪对磁流变液的零场粘度和剪切强度进行了测试。结果表明,在相同磁场强度下,两种粒径磁流变液的剪切强度比单一粒径磁流变液的有明显提升,提升效果与颗粒的成份密切相关,且其零场粘度和沉降稳定性与单一粒径的差别很小。     

溶胶—凝胶法制备SiO2薄膜的研究

硅溶胶制备ＳｉＯ２薄膜时用正交试验法系统研究了各种因素对溶胶稳定性和ＳｉＯ２薄膜成膜性的影响。研究表明：溶液浓度,加水量和催化剂是制备良好成膜性溶胶的关键因素,控制干燥化学添加剂在加入量超过一定比例后对抑制膜层开裂有明显作用。     

静电纺丝法制备超疏水氟硅改性纳米SiO_2/PET共混膜

利用1H,1H,2H,2H-全氟辛基三氯硅烷对SiO_2纳米粒子进行表面改性,制备得到氟硅改性SiO_2纳米粒子(M-SiO_2),并将其与聚对苯二甲酸乙二酯(PET)共混后溶于六氟异丙醇(HFIP)溶剂中进行静电纺丝。采用接触角测量仪、扫描电镜和X射线光电子能谱研究了M-SiO_2/PET电纺膜的疏水性能、表面形貌以及化学组成。结果表明,静电纺丝法制备的M-SiO_2/PET共混电纺膜对水的接触角可高达155.2°,并且对水的滞后角仅为3.4°,即具有超疏水性能。     

细乳液法合成单核核壳结构氧化硅/聚苯乙烯复合微球

采用细乳液聚合法,以3-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)表面改性的直径50nm的氧化硅粒子为核,在乳化剂、助乳化剂、引发剂存在的情况下制备了小粒径、单核核壳结构氧化硅/聚苯乙烯纳米复合微球.研究表明,苯乙烯的浓度、超声细乳化时间,是制备这种小粒径、单分散、单核核壳结构的氧化硅/聚苯乙烯纳米复合微球的关键因素.透射电镜(TEM)的观察显示,在优化的实验条件下,可以制得平均粒径95nm,壳厚20nm,粒径均一、球形规整度较好、单核核壳结构的氧化硅/聚苯乙烯纳米复合微球.其平均粒径远低于用其它聚合方法制备的复合微球.     

静电自组装法制备的纳米多层膜的吸波性能

配制了钡铁氧体溶胶和PSS（聚苯乙烯磺酸钠）溶胶,并利用静电自组装的方法在硅片上组装了纳米多层膜。利用紫外-可见分光光度计测出了单层最佳组装时问及每个双层的层厚。用SEM和XPS考察了纳米多层膜的表面形貌和铁元素的价态。对纳米多层膜进行吸波测试,结果显示：总层数为45个双层、总厚度为300nm左右的纳米多层膜有显著的吸波效应,在频率为8～18GHz范围内,最大吸波率达到16．85dB。基于量子理论探讨了纳米多层膜的吸波机理。     

Effectiveness of amorphous silica encapsulation technology on welding fume particles and its impact on mechanical properties of welds

Stainless steel welding generates nano-sized fume particles containing toxic metals which may cause serious health effects upon inhalation. The objective of this study was to investigate the effectiveness of an amorphous silica encapsulation (ASE) technology by evaluating its silica coating efficiency (SCE), particle morphology, and its impact on the weld’s mechanical properties. Tetramethylsilane (TMS) added to the welding shielding gas decomposed at the high-temperature arc zone to enable the silica coating. Collected welding fume particles were digested by two acid mixtures with different degrees of silica solubility, and the measured mass differences in the digests were used to determine the SCE. The SCEs were around 48–64% at the low and medium primary shielding gas flow rates. The highest SCE of 76% occurred at the high shielding gas flow rate (30 Lpm) with a TMS carrier gas flow of 0.64 Lpm. Transmission electron microscopy (TEM) images confirmed the amorphous silica layer on the welding fume particles at most gas flow rates, as well as abundant stand-alone silica particles formed at the high gas flow rate. Metallography showed that welds from the baseline and from the ASE technology were similar except for a tiny crack found in one particular weld made with the ASE technology. Tensile tests showed no statistical difference between the baseline and the ASE welds. All the above test results confirm that welding equipment retrofitted with the ASE technology has the potential to effectively address the toxicity problem of welding fume particles without affecting the mechanical properties of the welds.     

Superhydrophobic sodium silicate based silica aerogel prepared by ambient pressure drying

The superhydrophobic silica aerogel was prepared by using less expensive sodium silicate as a main silica source through a cost-effective and simple route via ambient pressure drying. The sodium impurity was first eliminated by mixing sodium silicate with a co-precursor methyltriethoxysilane (MTES) followed by ion exchange process. The hydrogel was formed by gelation and the alcogel was further obtained by alcoholization of the hydrogel. The surface of alcogel was modified by reacting with trimethylchlorosilane (TMCS) diluted in n-hexane. It was suggested that MTES accelerated water expelling from the hydrogel, while TMCS modified the surface of silica network by replacing Si–OH with Si–C. As a result, the obtained silica aerogel exhibited excellent physical properties with less than 10% volume shrinkage. The density, surface area and cumulative pore volume were 0.12 g cm⁻³, 684.44 m² g⁻¹, and 3.55 cm³ g⁻¹, respectively. The optical transmission reached 82.8% with the water contact angle of 146°.     

RF-PECVD制备类金刚石膜的研究

采用RF-PECVD法在锗(Ge)基片上沉积类金刚石(DLC)薄膜,研究了气体流量和气压对沉积区域均匀性的影响,以及基片厚度与沉积时间的关系。用拉曼光谱(Raman)分析DLC膜的结构组成,用傅立叶红外光谱仪(IR)对DLC膜的透过率进行了测量。结果表明,在气体流量为50 sccm,气压为10 Pa,功率800 W条件下薄膜厚度均匀性可达2.1%,极值透过率达62%。     

Superhydrophobic transparent films from silica powder: Comparison of fabrication methods

The lotus leaf is known for its self-clean, superhydrophobic surface, which displays a hierarchical structure covered with a thin wax-like material. In this study, three fabrication techniques, using silicon dioxide particles to create surface roughness followed by a surface modification with a film of polydimethylsiloxane, were applied on a transparent glass substrate. The fabrication techniques differed mainly on the deposition of silicon dioxide particles, which included organic, inorganic, and physical methods. Each technique was used to coat three samples of varying particle load. The surface of each sample was evaluated with contact angle goniometer and optical spectrometer. Results confirmed the inverse relationships between contact angle and optical transmissivity independent of fabrication techniques. Microstructural morphologies also suggested the advantage of physical deposition over chemical methods. In summary, the direct sintering method proved outstanding for its contact angle vs transmissivity efficiency, and capable of generating a contact angle as high as 174°.     

Superhydrophobic and Anti-Icing Surface by Femtosecond Laser Direct Writing

Glass fiber-reinforced polymer (GFRP) is formed with glass fiber as the reinforcing material and resin as the matrix. It is widely used in wind turbine blades because of its lightweight, high strength, and corrosion resistance properties. Herein, a method to prepare superhydrophobic GFRP surfaces by femtosecond laser direct writing combined with fluoroalkylsilane modification is demonstrated. The prepared GFRP surface has excellent superhydrophobicity with contact angle of 163.9° and sliding angle of 3.8°. In the ice resistance tests, the icing delay time is extended from 33 to 273 s at −5 °C. The ice adhesion strength is reduced from 217.4 to 40.3 kPa. The surface still has superhydrophobicity and ice adhesion strength of less than 100 kPa after ten cycles of the test. The laser exposure conditions are optimized for water/ice repelling and are at high intensity of 4 TW cm⁻² pulse⁻¹ and 2.5 m s⁻¹ beam travel speed, which make the presented approach efficient for fabrication over industrially large areas.     

Adjuvant properties of mesoporous silica particles tune the development of effector T cells

Alum is the most frequently used adjuvant today, primarily inducing Th2 responses. However, Th1‐type responses are often desirable within immune therapy, and therefore the development of new adjuvants is greatly needed. Mesoporous silica particles with a highly ordered pore structure have properties that make them very interesting for future controlled drug delivery systems, such as controllable particle and pore size; they also have the ability to induce minor immune modulatory effects, as previously demonstrated on human‐monocyte‐derived dendritic cells (MDDCs). In this study, mesoporous silica particles are shown to be efficiently engulfed by MDDCs within 2 h, probably by phagocytic uptake, as seen by confocal microscopy and transmission electron microscopy. A co‐culture protocol is developed to evaluate the capability of MDDCs to stimulate the development of naïve CD4⁺ T cells in different directions. The method, involving ELISpot as a readout system, demonstrates that MDDCs, after exposure to mesoporous silica particles (AMS‐6 and SBA‐15), are capable of tuning autologous naïve T cells into different effector cells. Depending on the size and functionalization of the particles added to the cells, different cytokine patterns are detected. This suggests that mesoporous silica particles can be used as delivery vehicles with tunable adjuvant properties, which may be of importance for several medical applications, such as immune therapy and vaccination.     

透明隔热纳米涂料的研究进展

本文就透明隔热纳米涂料的国内外研究进展、纳米材料的选材、隔热机理及制备方法进行综述,并就其现存的问题和未来的发展进行了展望。     

Antibioadhesive Superhydrophobic Syringe Needles Inspired by Mussels and Lotus Leafs

Fouling of surfaces due to bioadhesion is one of the hurdles in terms of their practical applications. Inspired by mussel and lotus leaf, antibioadhesive superhydrophobic syringe needles are fabricated by sequential bonding of polydopamine, Ag nanoparticles, and 1H,1H,2H,2H‐perfluorodecanethiol (PFDT). The morphology and surface chemical composition of the needles are characterized. The wetting properties and antibioadhesive properties of the needles are evaluated by contact angle (CA) and sliding angle (SA) of water and various aqueous solutions, and their residues on the needles after repeatedly used for liquid handling. The superhydrophobic needles show a rough surface with a layer of PFDT, which endow them with very high CA and low SA for water and various aqueous solutions. In addition, the aqueous solutions are in the Cassie–Baxter state on the surface of the superhydrophobic needles. Thus, the adhesion force between the superhydrophobic needles and aqueous solutions is very low. This endues the needles with excellent antibioadhesive properties and can be repeatedly used for withdrawing and dispensing various aqueous solutions. Moreover, the superhydrophobic needles can be used for the transport of aqueous solutions at high accuracy. The antibioadhesive superhydrophobic needles may find applications in various fields such as liquids transport and inkjet printing devices.     

基于真空辅助层层自组装的透明柔性纳米芳纶薄膜的制备

通过二甲基亚砜（DMSO）-KOH体系溶解宏观芳纶纤维（AF）成功制备了直径为40~50 nm、长度为2~5 μm的纳米芳纶纤维（NAF）,并利用SEM、TEM、FTIR、Raman和XRD对NAF和AF的微观形貌、化学结构、结晶结构进行了分析。结果表明,NAF与AF具有相似的化学结构,同时NAF保留了AF大部分的结晶结构,只是纤维尺寸有一定的差异。通过真空辅助层层自组装法制备了具有层状致密结构的NAF复合薄膜,该薄膜展现出很好的透明、柔性、耐温性和力学性能,具有一定的亲液性能（接触角为81.5°）及优异的抗液体渗透和抗液体吸收性能。      

近红外反射超疏水黄色涂层的制备和性能

将钛铬棕粉末(TCB)、金红石型二氧化钛(TiO₂)、疏水纳米二氧化硅(SiO₂)与聚二甲基硅氧烷(PDMS)溶液混合,一步刷涂制备出超疏水黄色涂层,系统地研究了涂层的表面润湿性、疏水稳定性、耐紫外线老化性能、自清洁性能、以及近红外反射性能。结果表明,这种涂层的水接触角(CA)和滚动角(SA)分别为155.2°和5.4°;涂层在1.0 kPa的压力下经过2 m距离的砂纸磨损后和5 L的水流冲击后依然保持优异的疏水性,其附着力和硬度分别达到2级和6B等级;不同pH值的溶液在涂层表面都具有超疏水效果并具有化学稳定性;用紫外线照射240 h后涂层表面仍然保持极强的疏水性,表明其具有耐紫外线老化性能;涂层表面具有优异的自清洁性能,污染物极易地被水滴带走;涂层的近红外反射率和太阳反射率分别达到0.858和0.672,对普通水泥板具有明显的降温效果,在户外暴露和水流冲击后仍保持较高的反射率。     

多功能单层二氧化硅增透膜的设计与制备

通过膜层设计软件(TFCalcTM)设计了在400~1 100nm波长范围内具有高透过率的单层增透膜。以正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)为共混前驱体、盐酸为催化剂、十六烷基三甲基溴化铵(CTAB)为模板剂制得甲基修饰的二氧化硅溶胶,通过浸渍提拉法结合溶剂挥发自组装技术成功制备了所设计的多功能单层增透膜。结果表明,(1)增透膜在650nm的最大透过率可达到99.9%,在400~1 100 nm波长范围内的光伏透过率(TPV)高达98.7%,与软件设计结果一致;(2)TEOS与MTES共聚后,显著提高增透膜的疏水性,其对水的接触角从24°提高至85°;(3)单层二氧化硅增透膜具有较好的耐磨擦性。这种兼具高透过率、耐磨擦性和一定疏水性的多功能增透膜在太阳能电池领域具有应用价值。     

自组装法制备中空二氧化硅纳米粒子减反射薄膜

以正硅酸乙酯(TEOS)为壳层材料, 聚丙烯酸(PAA)为核材料, 以传统的Stöber水解法为基础制备得到结构规整的中空二氧化硅纳米粒子, 并采用自组装法制备单层减反射薄膜和宽波段双层减反射薄膜。主要研究中空二氧化硅纳米粒子的结构调控方法; 自组装次数和中空二氧化硅纳米粒子分散液的pH值对减反射薄膜透光率的影响规律, 以及具有渐变折射率的双层减反射薄膜的制备。研究结果表明: 通过调节PAA和TEOS的用量可精确调控中空二氧化硅纳米粒子的粒径和空腔体积分率, 进而可精确调控减反射薄膜的厚度和折射率; 通过酸洗工艺, 将自组装次数由10次减少为2次, 简化了涂膜的工艺条件, 在最佳工艺条件下所制备的单层减反射薄膜在350~800 nm波长范围内可显著提高玻璃的透光率, 在最佳波长(λ=520 nm)处将玻璃的透光率由91.6%提高至98.1%; 双层减反射薄膜可在更宽的波段范围内提高基材的透光率, 在400~1500 nm波长范围内将玻璃的透光率提高了5%以上。