【作者】 陈慧琴；

【导师】 程江；

【作者基本信息】 华南理工大学 ， 化学工程， 2011， 博士

【摘要】 预涂金属卷材由于其多变的色彩,轻便,易加工及优越的机械性能,越来越多的被应用到建筑、汽车、家电面板等领域。现代城市中,作为外墙建筑在使用的环境中,涂膜时刻遭受外界各种各样的污染。建筑物的保洁一直是难题,因此开发一种低表面能防涂鸦耐污型涂料迫在眉睫。含氟丙烯酸酯聚合物具有良好的特性,如疏水疏油性、化学惰性、热稳定性和良好的机械性能等特点,是目前防涂鸦涂料研究的热点方向之一。然而,要获得优异表面性能往往需要耗费大量昂贵的含氟单体,而且含氟丙烯酸酯聚合物在极性环境中容易发生表面重建,从而丧失了优异的表面性能。因此人们希望在满足性能要求的同时,尽量减少氟单体的用量。以较少含氟量构造具有优异表面性能的疏水疏油表面一直是当今一个巨大的挑战。本文合成了含氟丙烯酸酯共聚物,将无机纳米二氧化硅（SiO₂）粒子掺杂到含氟丙烯酸酯共聚物中,通过交联固化得到含氟丙烯酸酯/SiO₂复合涂层。复合涂层具有好的超疏水和疏油性。主要内容包括:（1）以全氟辛基乙基甲基丙烯酸酯（FOEMA）和不同烷烃链长丙烯酸酯(AA,CH₂=CHCOOC_nH_2n+1,n=4,8,12,16,18)为单体,二甲苯做溶剂,BPO为引发剂,用自由基聚合法合成一系列的含氟丙烯酸酯聚合物。通过傅立叶红外光谱仪（FTIR）、核磁共振光谱（¹HNMR）、凝胶渗透色谱法（GPC）、X-射线衍射仪（XRD）、偏光显微镜（POM）和差示扫描量热仪（DSC）等对含氟丙烯酸酯共聚物化学组成和结晶性进行了分析。结果表明:结晶性与碳氢侧链长密切相关,当n=4,8,12时,在室温下不具有结晶性,为无定形物质;当n=16,18时在室温下结晶。而共聚物组成决定了晶体结构:当氟含量较低时,共聚物主要以烷烃侧链结晶为主;当氟含量较高时,共聚物主要以全氟侧链结晶为主。（2）利用分子动力学模拟软件MaterialStudio中Forcite模块下,在COMPASS力场下,模拟了含氟丙烯酸酯共聚物的X-射线衍射谱（XRD）,研究了不同碳氢侧链长度对结晶性的影响。模拟结果与实验数据基本符合。（3）研究了不同碳氢链长的含氟丙烯酸酯共聚物涂膜的表面润湿性,考察了共聚物结晶性对涂膜的表面润湿性的影响,并对共聚物进行了表面成分和形貌分析。结果发现:碳氢侧链的结晶有利于全氟侧链往表面迁移,相较无定形共聚物,结晶共聚物涂膜中氟元素在表面富集度更高,表面疏水疏油性更好。结晶态共聚物涂膜有着明显的相分离,而相分离导致固体表面的粗糙度大大增加,提高了其表面的疏水性。在氟单体用量少的情况下,要得到疏水和疏油性能良好的涂膜,可以通过选择合适的丙烯酸酯单体,制备结晶态共聚物。（4）以丙烯酸十八酯、氟单体和甲基丙烯酸羟乙酯进行共聚,合成热固性树脂,考查了羟基单体用量和成膜条件对涂膜表面润湿性和机械性能的影响。XRD和DSC结果证明热固性共聚物结晶度比其热塑性共聚物结晶度大,分子排列更规整。XPS和AFM发现热固性共聚物中氟元素更易在表面富集,这是因为热固性共聚物的交联结构能将全氟链段被固定在表面,限制分子迁移与重排,因此具有更好的疏水疏油性和表面稳定性。（5）采用直接共混的方法,将二氧化硅粒子掺杂到含氟丙烯酸酯共聚物中,通过交联固化得到含氟丙烯酸酯/SiO₂复合涂层,分别考察了二氧化硅粒子加入量和涂层溶液浓度复合涂层表面润湿性的影响,结果表明:二氧化硅粒子添加量和涂层溶液的浓度对滤网涂层表面粗糙度具有重要影响,从而显著改变了涂层的疏水亲油性。当二氧化硅添加量为20%,溶液浓度为10 %得到的复合涂层疏水疏油性最佳。测试了复合涂层防涂鸦耐污性和机械性能,防涂鸦耐污性比市售的改性有机硅类涂料和聚氨酯类涂料更好,机械性能均已达到使用要求。更多还原

【Abstract】 Due to properties of variety of colours, easy cut to required lengths, flectional, profiled or deep drawn, without damaging the organic coating, the prepainted coil has numerous applications in various industries, such as in the construction industry, the automotive and transport industries,etc. Films may suffer from all kinds of outdoor pollution as outside walls of building coatings in modern cities. It is extremely urgent to develop a kind of anti-graffiti and anti-fouling coil coating with the low surface energy because buildings cleaning is a challenge.?Fluorinated acrylate copolymers have become one of hot topics as anti-graffiti and anti-fouling coating due to their many special properties, including hydrophobicity and oleophobicity, chemical inertness, and thermal resistance, as well as excellent mechanical behavior. However, the fluorinated monomers are usually costly and the excellent surface performance of fluorinated acrylate copolymer may be lost when exposed in polar environment induced by surface reconstruction, it is challenging to fabricate excellent surface performance of hydrophobicity and oleophobicity with lower fluorine content. In this paper, fluorinated acrylate copolymer was synthesized and SiO₂/polyacryalte composite coating was prepared before further curing with HDI-trimer. Composite coating has good surper hydrophobicity and oleophobicity. The main research contents are listed as follows:First of all, a series of fluorinated acrylate copolymers by using monomers of 2-perfluorooctyl ethyl acrylate （FOEMA） and various lengths of side chains of n-alkyl acrylates （AAs） （n= 4, 8, 12, 16, 18） were synthesized by free radical polymerization in solvent of xylene and initiator of BPO. The copolymer chemical composition and crystallization were analyzed via Fourier Transform Infrared Spectroscopy （FTIR）, Nuclear magnetic resonance spectrum（¹HNMR）, gel permeation chromatography （GPC）, X-ray Diffraction（XRD）, Polarizing Optical Microscope（POM） and Differential Scanning Calorimetry （DSC） etc. The results suggest that crystallization of fluorinated acrylate copolymers closely related to the side-chain length of hydrocarbon. When n numbers of C_nH_2n+1 were 16 and 18, the hydrocarbon side-chain of the copolymers crystallized at room temperature, while the copolymers with n of 4, 8 and 12 might not crystallize and was in the rubbery state at the same condition. The crystalline structure is determined by the copolymer composition: when the content of the fluorinated monomer is low, the copolymer is mainly crystallized with side chains of hydrocarbon chains; when the content of the fluorinated monomer is high, the copolymer is mainly crystallized with perfluoroalkyl side-chain.Secondly, molecular dynamics simulation was used to simulate X-ray Diffraction of fluorinated acrylate copolymers by Forcite module under COMPASS force field. The effect of different length of hydrocarbon side-chain on crystallization of fluorinated acrylate copolymers was studied. Simulation results were consistent with experiment date.Thirdly, surface wetting properties of fluorinated acrylate copolymers with different length of hydrocarbon side-chain were investigated and the effect of crystallization of fluorinated acrylate copolymers on surface wetting properties of films was discussed. In addition, surface composition and topography of copolymers were analysed. The results suggest that the crystallization of hydrocarbon side-chain can promote perfluoroalkyl side-chain to migrate to the polymer–air interface. Compared with amorphous copolymer, the enrichment of fluorine on surface of crystalline copolymers film is higher, and hydrophobicity and oleophobicity on those surface is better. Phase separation is observed obviously on crystalline copolymers film, moreover, it lead to a great increase in roughness and hence improve hydrophobicity. Preparation of crystalline copolymers through choosing a suitable acrylate monomer is an available way to get good hydrophobic and oleophobic copolymer film under the condition of low dosage of fluorinated monomer.Furthermore, thermosetting resin is synthetized by using monomers of stearyl acrylate, fluorinated monomer and hydroxyethyl methacrylate. The influence of hydroxylic monomer dosage and film formation condition on surface wetting and mechanical properties were investigated. XRD and DSC results indicated that the crystallinity of thermosetting copolymer is bigger than that of thermoplastic copolymer and the molecular arrangement is more orderly. XPS and AFM shows the fluorine of thermosetting copolymer prefer to enrich on the film suface, for perfluoroalkyl side-chain of thermosetting copolymers can be fixed on the surface by the cross-linked structure, which limitied molecular migration and rearrangement. Therefore it has better hydrophobicity and oleophobicity and surface stability.Finally, SiO₂/polyfluoroacrylate composite coating were prepared by directly blending nano-silica particles into fluorinated acrylate copolymer and further cured with HDI-trimer. The effects of silica dosage and concentration of coating solution on the wettability of composite coating were studied. The results suggest that the silica dosage and concentration of coating solution have important influence on the roughness of the composite coating. The composite coating has best hydrophobicity and oleophobicity when the silica dosage is 20% and the concentration of coating solution is 10%. Anti-graffiti, anti-fouling and mechanical properties of the composite coating were tested to be better than those of some commercial products with modified silicone and polyurethanes coating.更多还原