Polysilazane Film Composition for Storage Stability
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Solution Overview
Problem
Existing methods for forming water repellent films on substrates face issues with chemical stability and storage stability due to the use of low-reactivity silane compounds, which can lead to volatility and precipitation of insoluble solids, and high-reactivity chlorosilanes that result in unstable coating solutions.
Innovation Solution
A water repellent film-forming composition comprising a polysilazane with a specific structure, untreated metal oxide nanoparticles, and an aprotic solvent, where the polysilazane has a C3-C20 monovalent hydrocarbon group bonded to a silicon atom, and the nanoparticles have an optionally fluorinated C1-C20 monovalent hydrocarbon group or alkylsilyl/alkoxysilyl group on their surface, providing improved stability and reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If low-reactivity silane compounds are used to form water repellent films, then chemical stability is improved, but storage stability deteriorates due to volatility and precipitation of insoluble solids
Solution Approach 1:
The patent changes the chemical reactivity parameter of the silane compound by introducing a hydrolyzable group (alkoxysilyl or halosilyl) that enables controlled hydrolysis and condensation reactions. This parameter change transforms the low-reactivity silane into a polysilane with enhanced stability while maintaining solubility and preventing precipitation during storage.
Solution Approach 2:
The patent creates a composite water repellent film combining polysilane polymer chains with hydrophobic alkyl or fluoroalkyl groups. This composite structure integrates the stability of the polysilane backbone with the water repellency of the hydrophobic side chains, achieving both chemical stability and storage stability simultaneously.
2Speed
If high-reactivity chlorosilanes are used to form water repellent films, then film formation speed is improved, but coating solution stability deteriorates
Solution Approach 1:
The patent performs preliminary hydrolysis of the alkoxysilyl or halosilyl groups to form silanol intermediates before coating application. This preliminary action enables controlled polymerization after coating, achieving fast film formation while maintaining coating solution stability during storage through the use of stable precursors.
Solution Approach 2:
The patent introduces silanol groups as intermediary species that mediate between the stable precursor (alkoxysilane or halosilane) and the final crosslinked polysilane network. These silanol intermediates enable controlled reaction kinetics, providing both solution stability and rapid film formation when triggered by moisture.
3Stability of the object's composition
If a smooth surface is used for water repellency, then water contact angle can be increased, but droplet sliding properties deteriorate
Solution Approach 1:
The patent creates local quality variations on the film surface by incorporating microparticles with different sizes, shapes, and surface properties. These localized heterogeneities generate microscopic irregularities that reduce adhesion between water droplets and the surface, enabling droplet sliding while maintaining high water contact angle through the hydrophobic polysilane matrix.
Solution Approach 2:
The patent utilizes the porous or micro-rough structure formed by packed microparticles to create air pockets between water droplets and the solid surface. This porous structure reduces the actual contact area between water and solid, enhancing both water repellency (high contact angle) and droplet mobility (sliding properties) simultaneously.
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 composition achieves good storage stability and forms a water repellent, especially superhydrophobic film with excellent water repellency, droplet sliding properties, and durability, maintaining performance even after washing.
Implementation Method 1
the polysilazane has a C3-C20 monovalent hydrocarbon group bonded to a silicon atom
Implementation Method 2
forms a water repellent, especially superhydrophobic film
Implementation Method 3
untreated metal oxide nanoparticles, metal oxide nanoparticles having an optionally fluorinated C1-C20 monovalent hydrocarbon group on their surface
Implementation Method 4
the nanoparticles have an optionally fluorinated C1-C20 monovalent hydrocarbon group or alkylsilyl/alkoxysilyl group on their surface
Data Source
AI summary
A composition is provided comprising (a) a polysilazane having a monovalent hydrocarbon group, (b) untreated metal oxide nanoparticles, metal oxide nanoparticles having a monovalent hydrocarbon group, or metal oxide nanoparticles having an alkylsilyl or alkoxysilyl group, and (c) an aprotic solvent. The composition has storage stability and is suitable for forming a film having water repellent, especially superhydrophobic properties.