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石墨烯基层状纳米材料改性水性涂层的制备及防腐蚀性能研究
杨凝
Subtype硕士
Thesis Advisor李伟华
2019-05-17
Degree Grantor中国科学院大学
Place of Conferral中国科学院海洋研究所
Degree Discipline海洋腐蚀与防护
Keyword水性涂层 改性 氧化石墨烯 聚苯胺 防腐蚀
Abstract

常用的传统有机涂料应用和储存过程涉及有毒挥发性有机物的排放,近年来环境友好的水性涂料越来越多的走进了人们的视线,然而水性涂料成膜过程易形成孔隙,造成屏障效果差,涂料与金属基体附着力差等缺陷,亟待解决。

石墨烯所具有许多显著特征,如尺寸效应,较高的疏水性和电导率。由于石墨烯基二维纳米材料独特的二维层状晶体结构和高各向异性,层状结构具有良好的可控性,可以通过升降维、插层和功能改性等方法对材料的性能进行调控,二维层状纳米材料比表面积大并且具有丰富的共轭结构和官能团附加位点,因此在电化学相关研究尤其是腐蚀与防护方向有极强的应用潜力。

导电聚苯胺及其取代衍生物易于化学或电化学合成,具有良好的环境稳定性,不同的氧化还原状态使其性能可调节,因此在防腐涂料中得到了广泛的应用。导电聚苯胺和氧化石墨烯的复合材料由于其优异的力学性能,电流变性能和屏障效应已应用于许多领域,但由于石墨烯与聚合物的结合力和兼容性不够强等因素,最终可能导致填料在提高防腐性能方面的局限性。

聚多巴胺具有无毒、可生物降解等绿色特性,是一种颇具发展前景的环保材料。氧化石墨烯骨架中含有大量多种含氧基团,可以与聚多巴胺发生反应,因此聚多巴胺有望作为分子连接剂将氧化石墨烯纳米片与基体表面连接,增强氧化石墨烯纳米片的粘附性,合成致密稳定的氧化石墨烯膜。纳米二氧化硅微球具有抗紫外线、耐化学性等优良性能,二氧化硅填料的添加能提高单一涂料的抗老化性能和力学强度,广泛的应用于特种涂层、防火材料、工业添加剂和建材防腐蚀等领域。

对二维层状氧化石墨烯纳米材料进行复合与改性,构建氧化石墨烯的空间结构并增强其在涂层中的分散性是改善涂料防腐蚀性能的可行方法。本文创新性地将氧化石墨烯与几种纳米级材料进行改性和复合,将复合物作为智能填料添加到水性涂层中对其进行改性,并探究改性后水性涂层的防腐机理。

通过设计实验,研究不同反应条件和配比参数对聚苯胺-氧化石墨烯、聚多巴胺-聚苯胺-氧化石墨烯、二氧化硅-聚苯胺-氧化石墨烯纳米复合物的形貌和性能的影响,优化实验参数。然后将氧化石墨烯、聚苯胺-氧化石墨烯、聚多巴胺-聚苯胺-氧化石墨烯、二氧化硅-聚苯胺-氧化石墨烯等作为填料添加到水性醇酸涂层,利用电化学阻抗测试和动极化曲线测试研究改性的水性涂层防腐蚀机理,同时研究改性的水性涂层的力学性能、涂层和基底的粘附性和涂层的疏水性能。

SEMFT-IRXRD等多种材料表征的结果表明聚苯胺-氧化石墨烯的最佳制备参数为室温反应18小时,电化学阻抗谱和动极化曲线表征结果显示聚多巴胺-聚苯胺-氧化石墨烯的最佳配比为21,聚多巴胺-聚苯胺-氧化石墨烯改性水性醇酸清漆的防腐性能提高,可能的机理是水性醇酸清漆的低表面张力,涂层在固化过程中易于产生微缺陷和收缩裂缝。在腐蚀性环境中,腐蚀性物质很容易通过微缺陷渗透涂层,严重腐蚀基板。而聚多巴胺-聚苯胺-氧化石墨烯复合材料的结构是纳米片层,同时具有均匀的纽扣形凸起,可以提供物理屏障效应并且增强涂层表面疏水效果,增加了腐蚀性物质接触和侵蚀材料的基体难度。此外,聚苯胺-氧化石墨烯含有大量刚性结构,聚多巴胺具有高粘性,因此复合材料可以填补纯水性醇酸清漆的缺陷和裂缝。而二氧化硅-聚苯胺-氧化石墨烯的配比为14时,二氧化硅-聚苯胺-氧化石墨烯改性水性醇酸清漆的防腐性能大幅提高,添加物的防腐机理是复合材料是由层状氧化石墨烯、珊瑚状的聚苯胺和二氧化硅球状纳米凸起构成的点线面结合的三维立体屏障结构,能够提供多方位的物理屏障效应,增加了腐蚀性物质接触基体表面的路径和腐蚀的难度,同时在聚苯胺-氧化石墨烯复合物的优异性能基础上,纳米二氧化硅增强了涂层的抗紫外线和耐化学性等性能。

Other Abstract

The application and storage process of conventional organic coatings involves the emission of toxic volatile organic compounds (VOCs) into atmosphere, which continuingly damaging the environment. In recent years, more and more environmentally friendly water-based coatings have drawn to people's attention. However, the film-forming process of water-based coatings is prone to form pores, resulting in poor barrier effect.

Graphene has many remarkable characteristics, such as size effect, high hydrophobicity and conductivity. The unique two-dimensional layered crystal structure, high anisotropy and good controllability of graphene based two-dimensional nanomaterial. And the two-dimensional laminar nano-material has a large specific surface area and rich conjugate structures and functional groups of additional sites. There are many methods of dimensionality reduction and inserted layer and the function of modification to adjust and control the performance of the material so graphene based two-dimensional materials have been used widely in the field of anti-corrosion has good application prospect.

Conductive polyaniline and its substituted derivatives are easy to be synthesized by chemistry or electrochemistry, have good environmental stability and different REDOX states, and can adjust their properties, so they are widely used in anticorrosive coatings. Conductive polyaniline and graphene oxide composites due to its excellent mechanical properties, electrorheological effect and the barrier performance have been applied in many fields. As a result of many factors such as low adhesion strength and compatibility of the individual elements of the polymer between graphene may not be strong, the application of fillers in improving anticorrosion performance were limitations. Polydopamine is a promising green material, which is non-toxic and biodegradable. Graphene oxide two-dimensional skeleton contains abundant oxygen-containing groups, which can react with the amine group of polydopamine. Therefore, polydopamine is expected to be used as molecular linkers to connect the graphene oxide nano-sheet to the surface of the metallic matrix, enhancing the adhesion of graphene oxide nano-sheet, and synthesized a dense and stable graphene oxide film. Nano-silica has excellent properties such as ultraviolet resistance, chemical resistance, as coating filler; it can improve the anti-aging performance and mechanical strength of the coating, and has been widely used in the fields of special coating, fireproof materials, industrial additives and building materials anti-corrosion.

The composite and modification of two-dimensional layered GO nanomaterial, increasing the spatial structure of graphene oxide and enhancing its dispersion in the coating are feasible methods to improve the anti-corrosion performance of the coating. This paper innovatively modified and compounded GO with different nanomaterial, by adding these composite as an smart filler into the water-based coating, and explored the anti-corrosion mechanism of the modified water-based coating.

The effects of different reaction conditions and ratio parameters on the morphology and properties of PANI-GO, PDA-PANI-GO and SiO2-PANI-GO nanocomposites were studied by orthogonal design, and the experimental parameters were optimized. Then the GO, PANI-GO, PDA- PANI-GO, SiO2-PANI-GO were used as fillers by adding into the water-borne alkyd coatings. Using electrochemical impedance tests and dynamic polarization curve tests studied the anticorrosion mechanism of modified waterborne coating, at the same time, the mechanical properties of modification of waterborne coating, the adhesion of the base and the coating and hydrophobic properties of the coating.

SEM, XRD, FT-IR and other materials characterization were conducted and the results show that the best preparation parameters of PANI-GO was reacting at room temperature for 18 hours, electrochemical impedance spectroscopy and dynamic polarization curves characterization results showed that best ratio of PDA and PANI-GO was 2:1. The anti-corrosion performance of PDA-PANI-GO modified waterborne alkyd varnish was improved; possible mechanism is due to the low surface tension of water-borne alkyd varnish, the coating prone to form micro defects shrinkage cracks in the process of solidification. In corrosive environments, corrosive substances can easily penetrate the coating through those micro-defects and then severely corrode the substrate. The structure of PDA-PANI-GO composite is nano-layer with uniform button shape, which can provide physical barrier effect and enhance the hydrophobicity of the coating surface, increasing the difficulty of the corrosive substances to contact the material and corroding materials. In addition, PANI-GO contains a large number of rigid structures and PDA is highly viscous, so the composite can fill the defects and cracks of pure water-based alkyd varnish. The ratio of SiO2 to PANI-GO is 1: 4; the SiO2-PANI-GO modified waterborne alkyd varnish anticorrosion performance is greatly increased.

The anticorrosive mechanism of the additives may due to structure of the composite which is the combination of layered GO, fibrous PANI and spherical SiO2. The three-dimensional barrier structure of point, line and plane, can provide all-round physical barrier effect, increase the difficulty of the corrosive substances to contact the material and the path of the surface to the substrate. Based on the excellent properties of PANI-GO compound, nano-SiO2 enhances the ultraviolet resistance and chemical resistance of the coating.

Language中文
Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/156833
Collection海洋环境腐蚀与与生物污损重点实验室
Recommended Citation
GB/T 7714
杨凝. 石墨烯基层状纳米材料改性水性涂层的制备及防腐蚀性能研究[D]. 中国科学院海洋研究所. 中国科学院大学,2019.
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