Colloidal-based self-assembly promoted stratified multifunctional coating with self-healing ability for superior adhesion strength and hardness Diksha Sharma and Dr. Debaprasad Mandal * Indian Institute of Technology, India Self-stratifying coatings refer to coatings that are designed to automatically separate into distinct layers with different functionalities or properties upon application. This stratification occurs due to the self-assembly of colloidal particles within the coating, driven by the interplay of attractive and repulsive forces between the particles. The self-assembly process enables the colloidal particles to organize themselves into well-defined, ordered structures within the coating, resulting in the formation of distinct layers with different compositions and functionalities. The behavior of colloidal particles in a coating influenced by various factors, including the size, shape, and surface chemistry of the particles, as well as the properties of the surrounding medium, such as the solvent and temperature. The concepts introduced here will help us better understand the recent development in coating technologies.
We developed a novel inorganic-organic hybrid coating material from the self-assembly of tannic acid (TA) with a network of PVA (polyvinylalcohol) and oligosiloxane, followed by in-situ acetalization with valeraldehyde to form bimodal micelles allowing the emergence of a self-stratifying system in THF/Ethanol solution. This hybrid coating material forms bimodal micelles allowing self-stratification by size segregation during drying to deliver multifunctional properties by a single coat on different surfaces. TA controls the assembly from unimodal to bimodal, suggesting that the small particles are the self-assembled PVA-oligosiloxane formed by the interaction of PVA with the surface silanol, but the larger particles are due to further assembly of few particles of PVA- oligosiloxane with TA. These types of multifunctional coatings provide outstanding performance by simultaneously improving surface and adhesion qualities, making them suitable for speciality coatings in varieties of industrial applications. It is challenging to create a hard, flexible, and transparent material for high adhesion strength for coating application by a single coat with self-healing and anti-icing properties. This highly crosslinked continuous network endows the coating with an excellent hardness of 1.0 GPa, adhesion strength up to 12.63 MPa on aluminium and good coating stability even after heating at 150 °C or in liq. N 2 . References 1. Liu, Z. Wang, P. Liu, Z. Wang, H. Yao, X. Yao, Sci. Adv. 2019, 5, eaaw5643.Beaugendre, S. Degoutin, S. Bellayer, C. Pierlot, S. Duquesne, M. Casetta, M. Jimenez, Prog. Org. Coat. 2017, 110, 210-241. 2. P. Howard, A. Nikoubashman and A. Z. Panagiotopoulos, Langmuir, 2017, 33 , 3685-3693. 3. Hou, G. Zhu, J. Cui, N. Wu, B. Zhao, J. Xu and N. Zhao, J. Am. Chem. Soc., 2022, 144 , 436-445. 4. R. Chen, Y. Zhang, Q. Xie, Z. Chen, C. Ma and G. Zhang, Adv. Funct. Mater., 2021, 31 , 2011145. 5. Li, F. Liu, S. Chen, A. Tsyrenova, K. Miller, E. Olson, R. Mort, D. Palm, C. Xiang, X. Yong and S. Jiang, Mater. Horiz., 2020, 7 , 2047-2055.
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