Single-Layer Superhydrophobic Coating via Silane-Functionalized SiO2
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Solution Overview
Problem
Current superhydrophobic coatings are costly and time-consuming to produce, requiring multiple layers and the use of fluorinated compounds, while also lacking in durability and resistance to chemical agents and dust detachment.
Innovation Solution
A single-layer superhydrophobic coating is achieved using a fresh acid suspension of SiO2 particles with specific size and functionalization, applied in a single step without a prelayer, providing excellent adhesion, chemical resistance, and abrasion resistance, even in acidic environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple layers of silica nanoparticles with different particle sizes are deposited, then superhydrophobic performance and durability are improved, but manufacturing complexity and production time increase
Solution Approach 1:
The patent combines multiple functional layers (adhesion layer and superhydrophobic layer) into a single composite coating layer applied in one step. The coating simultaneously provides substrate adhesion, superhydrophobicity, and mechanical durability through the synergistic combination of silane-functionalized silica nanoparticles and crosslinking agents, eliminating the need for separate layer deposition steps.
Solution Approach 2:
The coating composition is segmented into distinct functional components: silane-functionalized silica nanoparticles for adhesion and roughness, crosslinking agents for chemical bonding, and hydrophobic agents for water repellency. Each component performs a specific function, allowing the complex performance requirements to be achieved through a simplified single-layer structure.
2Reliability
If fluorinated compounds and multiple coating layers are used, then hydrophobicity and durability are enhanced, but production cost and time increase
Solution Approach 1:
The coating process uses continuous crosslinking reactions of silane groups that proceed at ambient or elevated temperatures to form a durable, chemically resistant network. This continuous chemical bonding process eliminates the need for multiple separate coating and curing cycles, reducing production time while maintaining durability and chemical resistance.
Solution Approach 2:
The patent replaces expensive fluorinated compounds with cost-effective silane-functionalized silica nanoparticles and common crosslinking agents. The coating achieves comparable or superior durability and chemical resistance using these cheaper, readily available materials, significantly reducing production costs.
3Strength
If a prelayer of silica nanoparticles is deposited first, then adhesion and roughness are improved, but the number of steps and production complexity increase
Solution Approach 1:
The patent merges the adhesion layer and superhydrophobic layer into a single coating application. The silane-functionalized silica nanoparticles in the coating simultaneously provide substrate adhesion through silane bonding and superhydrophobicity through surface roughness and hydrophobic agents, eliminating the need for a separate prelayer deposition step.
Solution Approach 2:
The silane-functionalized silica nanoparticles are pre-functionalized with adhesion-promoting silane groups before coating application. This preliminary functionalization ensures strong substrate adhesion is achieved as part of the single coating layer, eliminating the need for a separate adhesion-promoting prelayer.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The coating exhibits a static contact angle of over 135°, excellent resistance to acids and chemicals, and easy dirt removal, with improved mechanical and chemical durability, and is cost-effective and quick to produce.
Implementation Method 1
by depositing an outer layer of silica nanoparticles with a particle size of 70 to 300 nanometers in the presence of a silane compound onto a sublayer of silica nanoparticles
Implementation Method 2
a superhydrophobic coating having an outer surface for which a water droplet (10μl) placed on this outer surface in a horizontal position defines a static recoil contact angle of more than 135°
Data Source
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AI summary
The superhydrophobic coating comprises an outer layer having a thickness of less than 500 mu m, and an inner layer disposed above the outer layer. The coating is obtained by applying 97 wt.% of a fresh suspension acid constituted of solid particles having a size of less than 500 mu m, preferably 300 mu m, alcohol and/or mixture of alcohols comprising 1-6C, preferably 1-4C, 2-20 (preferably 3-15) wt.% of tetraethylorthosilicate, acid and water on a substrate at a temperature of = 20[deg] C and then drying to obtain the superhydrophobic coating. The superhydrophobic coating comprises an outer layer having a thickness of less than 500 mu m, and an inner layer disposed above the outer layer. The coating is obtained by applying 97 wt.% of a fresh suspension acid constituted of solid particles having a size of less than 500 mu m, preferably 300 mu m, alcohol and/or mixture of alcohols comprising 1-6C, preferably 1-4C, 2-20 (preferably 3-15) wt.% of tetraethylorthosilicate, acid and water on a substrate at a temperature of = 20[deg] C and then drying to obtain the superhydrophobic coating. The solid particles are constituted of more than 80 wt.%, preferably more than 90 wt.% of agglomerates of primary silicon dioxide nanoparticles. The primary silicon dioxide nanoparticles have a number average particle size of less than 70 nm, preferably 50 nm. The agglomerates of primary silicon dioxide nanoparticles: are functionalized with dimethyloxy and/or trimethyloxy to have a residual content of silicon hydroxide of 40-60%; and have a specific surface of 50-150 m 2>/g. The amount of particles is 0.6-6 (preferably 2-4) wt.%. A molar ratio of water and tetraethylorthosilicate is 0.5-2.5, preferably 0.5-1.5. A molar ratio of tetraethylorthosilicate and solid particles is 1-10. The primary silicon dioxide nanoparticles have a particle size distribution of 40 (preferably 100) nm, and a degree of polydispersity of greater than 0.2, preferably greater than 1. A molar ratio of silicon dioxide and tetraethylorthosilicate is 0.8-1.2. The external layer has a magnification factor of 50, a root mean square surface roughness of 1.1-20 mu m, and/or a wenzel roughness factor of greater than 1.2. An independent claim is included for a product including a side or a primary covering layer; and #a method for applying a superhydrophobic coating on a side of a product.