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/超润滑表面的防疏冰机理及其应用

超疏水/超润滑表面作为一种新的防疏冰方法,具有耗能低、重量轻、结构简单等优点,展现出了良好应用前景,却也存在一些问题,吸引了大量的学者开展了广泛的研究和讨论。本文从结冰的微观物理过程出发,结合实际应用背景,讨论了超疏水/超润滑表面的防疏冰机理及其影响因素;综述了防疏表面的相关研究成果及设计进展,总结了目前研究的问题,并进行了相关评述;同时提出了一种兼顾防冰和疏冰特性的性能评价方法;最后对防疏冰表面应用所面临的挑战进行了总结和展望。关于防疏冰表面研究进展的综述,不但可以深化我们对其作用机制的认识,更能为设计可工程化应用的防疏冰表面提供思路。     

抗结冰涂层: 从表面化学到功能化表面

在交通运输、航空航天、电力通信等诸多领域,结冰给人类和社会带来很大危害和安全隐患。现有的抗结冰方法如机械除冰、加热除冰以及喷洒化学试剂等虽然有效,但是存在耗能大和环境污染等问题。在基体表面涂装具有抗结冰性能的功能涂层被认为是一种必要的切实有效的方法,近年来备受关注。本文在介绍了涂层抗结冰原理及基体表面结冰影响因素的基础上,详细综述了近年来各类抗结冰涂层取得的研究成果,主要包括牺牲性涂层、疏冰涂层和超疏水涂层。重点介绍了制备抗结冰涂层所用的材料及方法,并分析了各种抗结冰涂层的优缺点,指出了抗结冰涂层目前存在的问题,最后对抗结冰涂层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。     

有机硅改性聚氨酯/纳米SiO2复合超疏水涂层的制备

以4,4'-二苯基甲烷二异氰酸酯(MDI)、聚四氢呋喃醚二醇(PTMEG)、羟基封端的聚二甲基硅氧烷(HO-PDMS)、1,4-丁二醇(BDO)为原料,合成了有机硅改性的聚氨酯溶液,通过核磁共振、红外光谱技术对其结构进行表征,并研究了羟基硅油加入量对聚氨酯热稳定性、疏水性的影响.以有机硅改性的聚氨酯溶液为基体、含氟硅烷偶联剂改性的纳米二氧化硅颗粒为填料,喷涂制备超疏水涂层,研究了填料添加量对复合涂层疏水性的影响.结果表明:当硅油加入量为9 wt%,填料加入量为60 wt%时,复合涂层性能最优,水接触角为153.3°,滞后角为6.3°.经过200℃加热1 h后,仍然具有大于150°的水接触角.对复合涂层进行磨损实验与防冰测试,结果表明:该复合涂层在磨损过程中,在基底暴露之前,整个涂层基体都具有超疏水性;并且该涂层能有效降低结冰温度,延长结冰时间,具有良好的防冰性能.     

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.     

防冰高分子材料

防冰高分子材料作为一种新型功能高分子材料,在电力、通讯及运输等领域有广泛应用.表面的覆冰现象往往开始于冰的成核,发展于冰的传递,危害于冰的积聚.针对材料表面冰晶形成的环节,揭示冰晶形成的分子机制是设计和开发防冰高分子材料的关键.本文简要介绍了本课题组在防冰高分子材料领域的研究进展,包括设计搭建的基本研究设备,以及具有调控冰成核、控制冰传递、降低冰黏附等不同功能的防冰高分子材料.     

柔性抗结冰表面的制备及其性能

冰的附着和累积是常见自然现象,但给人类社会带来诸多不便甚至发生重大事故。抗结冰表面是当前研究的热点课题之一,其表面特性是影响结冰最为关键的因素。但是结冰条件的复杂性及结冰类型的多样性致使抗结冰材料的研究面临很大挑战,存在的稳定性差、应用条件局限性等诸多问题尚未解决,不能满足实际应用的需求。本文根据表面分子的柔性或滑移性对抗结冰性能的影响,提出了柔性抗结冰表面的概念,总结了柔性抗结冰表面的种类(本征柔性表面、缓释柔性表面、润滑柔性表面)及其抗结冰机理和近年来取得的一些重要研究成果,并对柔性抗结冰表面存在的问题进行了分析,以期为抗结冰材料的研究提供新的研究思路和方法。     

低压供热涂层材料制备及热性能研究

低压供热技术具有安全系数高和节能降耗等优势,因而成为石化稠油长输管线、风力发电叶片冬季防覆冰和室内供暖等领域的研究热点之一。本文制备了一系列低压供热涂层材料,研究不同碳功能填料对涂层发热速率、发热功率及最高发热温度的影响规律,并揭示石墨烯和碳纤维对提升涂层材料热性能的协同作用。其中石墨烯纳米片的还原程度对材料热性能具有重要影响,降低其表面官能团密度对提升涂层供热特性具有促进作用,但是官能团密度过低会导致石墨烯纳米片的团聚现象,引起涂层发热不均匀。加入适量碳纤维可以提高石墨烯的均匀分散性,提升发热速率。优化石墨烯纳米片和碳纤维的比例后,采用24V电压驱动时,涂层材料的发热速率达到7.1℃·s^-1,功率密度为800W·m^-2,最高发热温度为124℃。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.