Surface modification method using a rare-earth metal oxide solution mixed with a binder

Hydrophobic surface coating technology for rare-earth oxides using carboxyl-containing polymer binders

This technology is a surface modification method that forms a hydrophobic surface by dissolving rare-earth metal precursors in ethanol, synthesizing rare-earth metal oxides with an aqueous hydroxide solution, and coating a substrate with a solution mixed with a carboxyl-containing polymer binder.

Hydrophobic surfaces created with conventional organic polymer modifiers are heat-sensitive, often losing their water-repellent properties due to thermal degradation at high temperatures. While rare-earth oxides offer excellent heat resistance and durability, simple coating of sol-gel synthesized nanoparticles has been limited by weak adhesion to substrates, causing the coating layer to peel off easily.

In this technology, the carboxyl groups of binders like polyacrylic acid form hydrogen bonds to firmly anchor CeO2 nanoparticles, creating a highly adhesive and thermally stable hydrophobic layer through simple wet processes like spin coating. It can be applied to heat-resistant water-repellent coatings for cookware and kitchenware, as well as semiconductor surface treatments, allowing for easy application of durable, high-temperature-resistant water-repellent layers on large-area substrates.

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Key Features:

• Step of preparing rare-earth metal oxides by adding an aqueous hydroxide solution to a solution of rare-earth metal precursors dissolved in ethanol
• Step of adding at least one carboxyl-containing polymer binder, such as polyacrylic acid, polyaspartic acid, or polyglutamic acid, to the rare-earth metal oxide solution
• Configuration using rare-earth metal nitrates or chlorides, such as cerium nitrate or cerium chloride, as precursors and forming oxides with 0.01–1M NaOH or KOH aqueous solution
• Step of spin-coating the rare-earth metal oxide and binder mixture onto silicon, silica, or platinum substrates 3–12 times, followed by sintering at 80°C

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This invention was developed with support from the Ministry of Education for research on easy superhydrophobic film formation using hydrophobic polymer and nanoparticle composites.

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