Organic-inorganic hybrid coatings for corrosion protection of aluminum alloys are promising alternatives to the current methods based on chromate passivation. This study examined the role of the polymer/silica ratio in terms of the hybrid nanostructure formed and its effect on the thermal stability and anticorrosive performance of the polymethyl methacrylate (PMMA)-siloxane-silica hybrid coatings. The chemical and nanostructural properties of the hybrid coatings assessed using Fourier transform infrared (FTIR) and small angle X-ray scattering (SAXS) were correlated with the thermal stability evaluated by thermogravimetry (TGA) and corrosion protection evaluated by electrochemical impedance spectroscopy (EIS) in saline/acid solution (NaCl 3.5 % + HCl pH 3). TGA showed that the high thermal stability (up to 287 °C) of the hybrid formulations with lower silica fractions is related to the adequate size and spacing of the siloxane nodes in the embedding polymer matrix. Correlation of SAXS and EIS measurements allowed to identify the specific molar ratios and nanostructural configuration in which the polymer and siloxane-silica nodes ideally combine forming thin PMMA-silica coatings (2−5 μm) that present long-term stability (> 6 months) with a corrosion resistance of up to 25 GΩ cm², being approximately 7 orders of magnitude higher than that of the uncoated Al2024-T3 substrate.

用于铝合金防腐的有机-无机杂化涂层是当前基于铬酸盐钝化方法的有前途的替代方法。这项研究检查了聚合物/二氧化硅比例对形成的杂化纳米结构的作用及其对聚甲基丙烯酸甲酯（PMMA）-硅氧烷-二氧化硅杂化涂层的热稳定性和防腐性能的影响。使用傅立叶变换红外（FTIR）和小角度X射线散射（SAXS）评估的杂化涂层的化学和纳米结构性质与通过热重分析（TGA）评估的热稳定性和通过电化学阻抗谱（EIS）评估的腐蚀防护相关在盐水溶液/酸溶液（NaCl 3.5％+ HCl pH 3）中溶解。TGA显示，具有较低二氧化硅含量的杂化配方的高热稳定性（高达287°C）与包埋聚合物基质中硅氧烷节点的适当大小和间距有关。SAXS和EIS测量值的相关性可以确定特定的摩尔比和纳米结构配置，其中聚合物和硅氧烷-二氧化硅节点理想地结合在一起，形成薄的PMMA-二氧化硅涂层（2-5微米），具有长期稳定性（> 6个月）耐腐蚀性高达25GΩcm^{如图2所示}，其比未涂覆的Al 2 O 4 -T 3衬底高大约7个数量级。