郝晓茹,张羽,谢军,盛伟.硬脂酸改性三氧化二铝表面润湿性的特性分析[J].表面技术,2023,52(6):400-409.
HAO Xiao-ru,ZHANG Yu,XIE Jun,SHENG Wei.Surface Wetting Characteristics of Aluminum Oxide Modified by Stearic Acid[J].Surface Technology,2023,52(6):400-409 |
| 硬脂酸改性三氧化二铝表面润湿性的特性分析 |
| Surface Wetting Characteristics of Aluminum Oxide Modified by Stearic Acid |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.06.037 |
| 中文关键词: 超疏水 分子动力学 两步喷涂法 纳米氧化铝 硬脂酸 润湿特性 |
| 英文关键词:superhydrophobic molecular dynamics two-step spraying nano alumina stearic acid wetting characteristics |
| 基金项目:河南省重点研发推广项目(202102210266);河南理工大学博士基金(B2018-31) |
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| Author | Institution |
| HAO Xiao-ru | School of Mechanical and Power Engineering, Henan Polytechnic University, Henan Jiaozuo 454003, China |
| ZHANG Yu | School of Mechanical and Power Engineering, Henan Polytechnic University, Henan Jiaozuo 454003, China |
| XIE Jun | School of Mechanical and Power Engineering, Henan Polytechnic University, Henan Jiaozuo 454003, China |
| SHENG Wei | School of Mechanical and Power Engineering, Henan Polytechnic University, Henan Jiaozuo 454003, China;Hami Yuxin New Energy Industry Research Institute, Xinjiang Hami 839000, China |
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| 中文摘要: |
| 目的 研究氧化铝经硬脂酸分子改性后的润湿行为，从表面改性角度探索聚合物自组装润湿性原理，进而制备出一种疏水性能良好的超疏水表面。方法 使用COMPASS力场进行分子动力学模拟，构建基于非键合粒子的Al2O3超晶胞模型体系，采用最速下降法和共轭梯度法进行优化，使所构建的模型在体系平衡下保持能量最小原则，并对其求解分析。进而基于模拟材料，通过两步喷涂法制备以改性纳米氧化铝为涂层的超疏水表面，观察表征特征，验证模型的正确性。最后从模拟构象、径向分布函数以及均方根位移方面分析氧化铝经硬脂酸分子改性前后水分子团簇在玻璃、氧化铝表面的微观润湿行为。结果 经硬脂酸改性后，氧化铝表面由亲水表面成为疏水表面。经分子动力学模拟表明，当硬脂酸浓度增加，每个硬脂酸的表面能由–110.5 kJ/mol变为–80.4 kJ/mol，硬脂酸分子降低了水分子团簇在玻璃和氧化铝表面的扩散系数，对疏水性的强弱有着重要的影响。结论 氧化铝颗粒与玻璃表面都具有强亲水性，且氧化铝对水分子的吸附能力要强于玻璃。硬脂酸能够降低氧化铝的表面能，且与纳米氧化铝发生化学反应后，将氧化铝由超亲水改性为超疏水。 |
| 英文摘要: |
| The work aims to study the wetting behavior of alumina particles modified by stearic acid from the microscopic point of view, in order to explore the wetting principle of polymer self-assembly from the surface modification, and then prepare a superhydrophobic surface with good durability. The method of molecular dynamics simulation and compass force field was used for molecular dynamics simulation and an Al2O3 supercell model system based on non-bonded particles was constructed and optimized by steepest descent method and conjugate gradient method, so as to keep the principle of minimum energy under system equilibrium and solve and analyze the model under periodic boundary conditions. Based on the simulation results, the superhydrophobic surface with cheap stearic acid and nano alumina particles as coating materials was prepared on the glass substrate by two-step spraying method. The contact angle was tested, the surface morphology and surface groups were analyzed, and the correctness of the model was verified from the macro point of view. The micro wetting behavior of water clusters on glass substrate and alumina surface before and after modification by stearic acid was analyzed by simulating conformation, radial distribution function and root mean square displacement. The contact angles of superhydrophobic surface and bare glass surface were 44.7° and 168.8° respectively. The surface morphology, infrared spectrum and group changes were observed. The results showed that the surface of alumina modified by stearic acid changed from hydrophilic surface to hydrophobic surface. Molecular dynamics simulation indicated that when the concentration of stearic acid increased, the surface energy of each stearic acid changed from –110.5 kJ/mol to –80.4 kJ/mol, but the surface energy did not decrease when it increased to a certain concentration. At this time, a layer of molecular film was formed under the action of stearic acid, the hydroxyl group at the head of stearic acid molecule was combined with nano alumina particles by hydrogen bond, and the methyl and methylene in its tail long carbon chain presented the surface hydrophobic characteristics. Thus, the diffusion coefficient of water molecular clusters on the surface of glass and alumina was reduced, and the cluster structure of water molecules on the surface was maintained, which had an important impact on the strength of hydrophobicity. Both alumina particles and glass surface have strong hydrophilicity, and the coordination number of aluminum and silicon particles on alumina surface and glass surface is not enough to fill the system. Therefore, there are some vacancies on the surface. After decomposition of H2O, the free OH– will occupy the vacancy, and the vacancy on aluminum ion surface is excess silicon, which shows that the adsorption capacity of alumina to water molecules is stronger than that of glass. Stearic acid can reduce the surface energy of alumina, and after chemical reaction with nano alumina, alumina is modified from super hydrophilic to superhydrophobic. The superhydrophobic surface remains superhydrophobic after three months, which proves that the superhydrophobic surface prepared in this experiment has stability and durability. By analyzing the surface morphology, it is found that the modified nano alumina particles will agglomerate and grow on the surface of glass carrier, and finally form micro nano rough structure similar to gully. |
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