超疏水涂层表面粗糙结构对防覆冰性能的影响

结冰给交通、电力输送和航空等领域带来极大的安全隐患,研究防覆冰技术具有重要的应用价值。目前最具前景的防冰方法是涂层防冰,本文介绍了疏水涂层的构建方法,阐述了涂层疏水性和疏冰性之间的关系;重点论证了涂层表面粗糙结构对其防覆冰性能的影响,指出防覆冰涂层研发中存在的问题,并对该领域的发展趋势进行了分析和展望。     

超疏水涂层防覆冰机理及制备

结构物表面严重覆冰有时会威胁人们的生命财产安全,影响经济社会的平稳运行。超疏水涂层具有超大接触角、低滚动角的特性,在防覆冰领域有很好的应用前景。本文重点总结了超疏水涂层防覆冰机理的相关研究结果,并简单综述了聚合物-微粒复合材料类、特殊表面结构类两种典型超疏水型防覆冰涂层的研究进展,指出了目前在超疏水型防覆冰涂层研究中存在的不足,并对其发展趋势进行了展望。     

防覆冰涂层构建机理及制备

航空、通信、电力和运输设备的覆冰现象给人们的生产、生活带来许多不便,甚至引起重大经济损失,防覆冰涂层主要通过材料表面特殊物理化学性能与微相形貌来实现抗冰目的,这类材料需要兼具防结冰性和疏冰性,从延长结冰时间和降低冰的附着力两方面来减轻甚至消除冰雪积聚,是目前研究的热点。本文从防覆冰机理入手,深入探讨了防结冰性和疏冰性的影响因素,阐述了防覆冰涂层材料的设计与制备方面的最新进展,并对防覆冰涂层目前存在的问题与发展方向进行了分析和展望。     

超疏水低粘着铜表面制备及其防覆冰性能

用喷砂处理在铜片表面形成微米级丘陵状凹坑,再用表面氧化处理在铜片表面制备菊花花瓣状CuO纳米片.通过喷砂-表面氧化处理在铜片表面成功构建了微米-纳米复合结构,这种表面氟化后与水滴的接触角高达161°,滚动角低至1°,显示出优异的超疏水性和很低的粘着性.低温下,这种表面与水滴间的热量交换较小,水滴不易凝结,有效地提高了抗结霜性.抗结霜性良好的超疏水铜有望在热交换器或低温运行设备等领域获得应用,这种简便的超疏水铜表面的制备方法也给其它工程材料超疏水表面的工业化制备提供了一个思路.     

微纳米结构复合表面的疏水-冰性能

通过软复型和水热法制备出一种由有机材料和ZnO纳米棒组成的微纳米结构复合表面,这种表面的微米结构是周期为300μm、高度为70μm的锯齿状结构,ZnO纳米线的直径为300~500 nm,长度为2~3μm.这种有机材料和ZnO纳米线复合成的表面经过全氟硅烷修饰后,具有良好的低黏滞特性和低温超疏水性(约为150°)以及较长的结冰延时性(6000~7630 s),实验结果对设计表面低温疏水/疏冰材料具有参考价值.     

硅烷表面修饰引发的ZnO微米棒膜的超疏水性

采用简单的低温水热法制备出ZnO微米棒薄膜,其经辛基三甲氧基硅烷和十二氟庚基丙基三甲氧基硅烷修饰后显示出超疏水性,静态接触角分别为(150±1.3)°和(155±1.5)°,滚动角依次为5°和3°。 ZnO微米棒的微结构和低表面能材料辛基三甲氧基硅烷、十二氟庚基丙基三甲氧基硅烷的表面修饰是其显示超疏水性的原因,用Cassie理论对膜的润湿性进行了分析。     

金纳米棒在超疏水表面的组装行为研究

采用了"烟囱效应"以及超疏水表面作为基底这两项外力作用来将金纳米棒进行组装。借用"烟囱"技术的侧面向心力所产生的向心空气气流,以及超疏水表面上液滴收缩产生的应力对纳米粒子的向心挤作用,得到了金纳米棒垂直于基片致密排列的特殊的组装花样以及金纳米棒水平短程有序的致密排列的组装花样。这种简便的组装方法不仅对纳米器件的应用有着重要的影响,而且可以广泛地适用于其他的纳米粒子的二维有序组装以得到不同的功能性的纳米组装体。     

表面修饰引发的ZnO纳米棒阵列膜的超疏水性

润湿性是固体表面的重要性质之一 ,它受控于固体表面自由能和表面粗糙度的大小 ,一般可用液体在固体表面接触角的大小来衡量 .由于水与超疏水表面 (水与固体表面的接触角大于 1 5 0°的表面 )的接触面积很小 ,通过水所发生的化学发应和化学键的形成受到限制 ,使这种表面具有防水、防污染和防氧化等多种功能 ,因而备受人们的关注 [1～ 6 ] .作为宽禁带半导体材料 ,Zn O以其独特的光电和催化等性质在短波激光器、气体传感器、高效催化剂、太阳能电池等方面具有广阔的应用前景 .表面润湿性的研究对于将 Zn O用于各种器件非常重要 .Pesika等 […     

防冰材料研究进展及其在风电领域的应用展望

新型防冰材料在风力发电领域具有非常广泛的应用前景。风机叶片表面的覆冰现象通常与冰的成核和冰生长两个因素息息相关。本文总结了本课题组在防冰材料方面的研究进展，包括抑制冰成核、防止冰生长、降低冰粘附力以及在低温与高湿等极端环境下具有光热除冰性能的防冰涂层。防冰材料技术的进步势必极大促进风电行业的发展，对我国的经济转型和能源结构调整具有重要意义。     

基于呼吸图法的环氧树脂基超滑液体灌注防冰涂层

通过呼吸图法构筑了多孔环氧树脂基底,并在此基础上通过聚二甲基硅氧烷改性以及二甲基硅油润滑液灌注制备了具有优异润滑性的液体灌注涂层.实验结果表明,基底表面孔径及孔隙率随着环境湿度增大而增大,且涂层在不同金属基底上都有良好的黏附性能.基于上述基底所制备的液体灌注涂层具有较低的滚动角(2°),且对多种液体具有良好的滑动性.该涂层被用于冰黏附的防治,展现出较低的冰黏附强度(175 kPa)及较长的延迟结冰时间(>600 s),表明其具有优异的防冰性能.     

微模塑法制备PMMA球面微透镜阵列

Micro-lens (ML) and Micro-lens array (MLA) are important optical components widely used in many fields;Soft-lithography, a vital little process technology, has its unique performance to produce ML and MLA;The cylinder and spherical MLA of polymethyl methacrylate (PMMA) were successfully obtained by micromolding inSoft-lithography. Some suitable experimental parameters in the process were discussed, and the imaging property of the MLA was also studied simply.     

薄层软刻蚀法制备PMMA微图案结构

对现有的软刻蚀方法提出了改进,让其与压印技术及毛细力刻蚀技术相结合形成一种薄层软刻蚀技术,并以这种技术制备出PMMA薄膜微图案化结构.在30 mm/h的拉膜速度以及弹性印章表面图形深度确定不变的情况下,PMMA流体能够完全填充到弹性印章的微通道中,SEM和光学显微镜照片证明得到的PMMA微图案是相互分离的.因此,薄层软刻蚀技术可以克服普通微模塑方法制备分离图形困难和纳米压印技术中需要使用巨大机械压力的缺点.     

Filler network structure in graphene nanoplatelet (GNP)-filled polymethyl methacrylate (PMMA) composites: From thermorheology to electrically and thermally conductive properties

In this work, graphene nanoplatelet (GNP) filled polymethyl methacrylate (PMMA) composites were prepared using solution method via a specially designed route and relatively high thermal conductivities of the composites were achieved at a low GNP loading. The effect of GNP content on rheological behavior, thermal and electrical conductivity of the composites was intensively investigated. Thermorheological complexity was displayed at elevated GNP loading, and the rheological percolation threshold of GNP in PMMA decreased from 7.96 wt% at 220 °C to 4.02 wt% at 260 °C according to Winter-Chambon method, suggesting that GNP was more likely to form a seepage network at higher temperature. The DMTA results showed that the increase in moduli of the composites should be ascribed to the formation of the GNP-GNP network structure. The electrical conductivity of the composites underwent a sudden jump by seven orders of magnitude, which also indicated the formation of a GNP conductive pathway in the matrix with an electrical percolation threshold of 2–4 wt%. The results of transient temperature measurement were in good consistent with the thermal conductivity versus GNP loading, which was compared with various thermal conduction models with a modified Agari model presenting an acceptable evaluation of the dispersion status of GNP in the matrix. The experimental electrical and thermal conductivities as a function of GNP content could well be interpreted by the filler network structure as observed in morphological studies.     

Effect of ZnO and organo-modified montmorillonite on thermal degradation of poly(methyl methacrylate) nanocomposites

Since a few years ago, a topic of interest consists in developing composites filled with nanofillers to improve thermal degradation and flammability property of poly(methyl methacrylate) (PMMA). In the present work, the effects of ZnO nanoparticles and organo-modified montmorillonite (OMMT) on the thermal degradation of PMMA were investigated by thermogravimetric analysis (TGA). PMMA-ZnO and PMMA-OMMT nanocomposites were prepared by melt blending with different (2, 5, and 10 wt%) loadings. SEM and TEM analyses of nanocomposites were performed in order to investigate the dispersion of nanofillers in the matrix. According to TGA results, the addition of ZnO nanoparticles does not affect the thermal degradation of PMMA under an inert atmosphere. However, in an oxidative atmosphere, two contrary effects were observed, a catalytic effect at lower concentration of ZnO in the PMMA matrix and a stabilizing effect when the ZnO concentration is higher (10 wt%). In contrast, the presence of OMMT stabilizes the thermal degradation of PMMA whatever be the atmosphere. Differential thermal analysis (DTA) curves showed surprising results, because a dramatic change of exothermic reaction of the PMMA degradation process to an endothermic reaction was observed only in the case of OMMT. During the degradation of PMMA-ZnO nanocomposites, pyrolysis-gas chromatography coupled to mass spectrometer (Py-GC/MS) showed an increase in the formation of methanol and methacrylic acid while a decrease in the formation of propanoic acid methyl ester occurred. In the case of PMMA-OMMT systems, a very significant reduction in the quantity of all these degradation products of PMMA was observed with increasing OMMT concentration. It is also noted that during PMMA-OMMT degradation less energy was released as the decomposition is an endothermic reaction and the material was cooled.     

烷基硫酸钠对MMA种子乳液聚合的影响

研究了烷基硫酸钠纯度，烷基碳链分布对甲基丙烯酸甲酯种子乳液聚合反应的影响。结果表明，烷基硫酸钠中乙醇不溶物含量的增加，可提高ＭＭＡ乳液聚合反应速度，在采用Ｋ２Ｓ２Ｏ８－ＮａＨＳＯ３－Ｃｕ＾２＋三元氧化－还原引发体系的ＭＭＡ乳液聚合中，Ｆｅ＾２＋降低反应速率，而Ｆｅ＾３＋则提高聚合反应速率；     

掺C60有机玻璃的吸收光谱研究

研究了Ｃ６０分别在有机玻璃（ＰＭＭＡ）和正己烷中的吸收光谱，发现Ｃ６０在有机玻璃中的吸收峰同在正己烷中相互对应，同时前者的吸收峰相对于后者峰宽变大，峰位产生红移，分析了产生这种现象的原因。     

The influence of β-FeOOH nanorods on the thermal stability of poly(methyl methacrylate)

Colloidal dispersions consisting of β-FeOOH nanorods with three different aspect ratios (4, 75 and 120) were synthesized using thermal hydrolysis of FeCl₃ solutions. After surface modification with oleic acid, the β-FeOOH nanorods were incorporated in poly(methyl methacrylate). Transmission electron microscopy and X-ray diffraction were applied for structural characterization of the β-FeOOH nanorods. The influence of inorganic phase on the thermal properties of PMMA matrix was studied using thermogravimetry and differential scanning calorimetry. Improvement of the thermal stability and increase of the glass transition temperature were found with the increase of content of inorganic phase and the increase of aspect ratio.     

Effects of clay‐modifying agents on the morphology and properties of poly(methyl methacrylate)/clay nanocomposites synthesized via γ‐ray irradiation polymerization

Via γ‐ray irradiation polymerization, poly(methyl methacrylate) (PMMA)/clay nanocomposites were successfully prepared with reactive modified clay and nonreactive clay. With reactive modified clay, exfoliated PMMA/clay nanocomposites were obtained, and with nonreactive clay, intercalated PMMA/clay nanocomposites were obtained. Both results were confirmed by X‐ray diffraction and high‐resolution transmission electron microscopy. PMMA extracted from PMMA/clay nanocomposites synthesized by γ‐ray irradiation had higher molecular weights and narrow molecular weight distributions. The enhanced thermal properties of the PMMA/clay nanocomposites were characterized by thermogravimetric analysis and differential scanning calorimetry. The improved mechanical properties of PMMA/clay were characterized by dynamic mechanical analysis. In particular, the enhancement of the thermal properties of the PMMA/clay nanocomposites with reactive modified clay was much more obvious than that of the PMMA/clay nanocomposites with nonreactive clay. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3218–3226, 2003     

Proton NMR investigation of the local dynamics of PEO in PEO/PMMA blends

Longitudinal relaxation of proton magnetisation was used to characterize the molecular motions of PEO chains in compatible PEO (hydrogenated)/PMMA (deuterated) blends. Both the temperature and the PEO concentration, Φ, were varied. A maximum in the spin–lattice relaxation rate was observed and its properties were analyzed as a function of Φ. For Φ ≤ 0.50, the maximum is observed below the glass transition temperature of the blend; this shows that PEO chains dispersed in a matrix of PMMA remain highly mobile on a local scale even below T_g(Φ). A frequency–temperature correspondence procedure, applied to the measurements performed at two Larmor frequencies, 32 and 60 MHz, leads to a characteristic correlation time for PEO molecular motions. Its temperature dependence obeys a WLF free volume relation above the glass transition of the blends. The PEO free volume fraction and its thermal expansion are strongly reduced by the presence of the PMMA chains. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1095–1105, 1997     

Controllable synthesis of nanosilica surface-grafted PMMA macromonomers via catalytic chain transfer polymerization

Catalytic chain transfer polymerization (CCTP) has emerged as an efficacious method to produce low-molecular weight polymers. In this paper, we reported the first controllable synthesis of nanosilica surface-grafted poly(methyl methacrylate) (PMMA) (SI-PMMA) macromonomers by using bis(aqua)bis((difluoroboryl)-dimethylglyoximato)cobalt(II) (CoBF) as a chain transfer catalyst via CCTP. In a typical run, we firstly prepared functionalized nanosilica by using 3-(trimethoxysilyl)propylmethacrylate (MPS) as the coupling agent, allowing naosilica containing unsaturated double bonds in end groups. Subsequently, SI-PMMA macromonomers were prepared by PMMA surface-grafted onto the functionalized nanosilica via CCTP. The as-prepared products were characterized by Fourier transforms infrared (FT-IR) spectrum, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transforms Raman (FT-Raman) spectrum and gel permeation chromatography (GPC). We also investigated the dependence of macromonomers on CoBF concentrations.