Ampholytic Polymers for Boron Nitride Dispersion Stability
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Solution Overview
Problem
Existing methods face challenges in effectively dispersing and stabilizing solid inorganic particles in liquid media, particularly in aqueous solutions, due to inadequate surface charge distribution, which affects their incorporation and stability in galvanic processes and other applications.
Innovation Solution
The use of specific water-soluble polymers, comprising a combination of monomers such as 3-trimethylammonium propyl methacrylamide chloride, N-isopropyl acrylamide, acrylic acid, and 2-acrylamido-2-methylesulfonic acid, which are ampholytic and increase the surface charge of particles, measured by zeta potential, to enhance dispersion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional dispersants or nonionic surfactants are used to stabilize solid particles, then some dispersion stability is achieved, but the particles can only be dispersed poorly or not at all in aqueous media due to inadequate surface charge distribution
Solution Approach 1:
The patent changes the surface charge parameter of particles by using ampholytic polymers that can reversibly change their charge state in response to pH changes or ionic strength variations. This allows the particles to transition between charged and neutral states, enabling effective dispersion in aqueous media while maintaining stability under processing conditions.
Solution Approach 2:
The invention employs composite polymer structures containing both cationic and anionic functional groups within the same polymer chain or mixture. These ampholytic polymers combine opposing charge characteristics to provide both dispersion promotion and stability, resolving the contradiction between achieving good dispersion and maintaining manufacturing ease.
2Stability of the object's composition
If surface-active substances are used as dispersants to prepare or stabilize dispersions, then dispersion stability is improved, but the surface charge on particle surfaces does not or only partially allow uniform incorporation into the solvent
Solution Approach 1:
The ampholytic polymers respond to changes in pH and ionic strength by reversing their charge, allowing uniform incorporation of particles into aqueous solvents. The charge reversal mechanism ensures that particles can be uniformly dispersed while maintaining stability, resolving the contradiction between dispersion stability and uniform incorporation.
3Stability of the object's composition
If electrostatic repulsion is used for stabilization, then particle stability is improved, but the complexity of the system increases due to the need for charged dispersants
Solution Approach 1:
The ampholytic polymers provide self-regulating electrostatic stabilization by automatically adjusting their charge state in response to environmental conditions. The polymers can switch between cationic and anionic states, providing electrostatic repulsion when needed without requiring external control mechanisms, thus maintaining particle stability while minimizing system complexity.
Data Source
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AI summary
Use of a polymer in the form of polymerized units comprising: (a) a monomer containing amide unit (I), (b) a monomer containing amide unit (II); (c) acrylic and/or methacrylic acid; and/or (d) further monomers comprising 3-6C ethylenically unsaturated carboxylic acids such as crotonic acid, maleic acid, maleic acid anhydride, fumaric acid, itaconic acid or their salts or half esters, or sulfonic acid compound (III) or their salts, preferably alkali metal- and ammonium salts for dispersing solid particles in liquid, preferably aqueous media, is claimed. Use of a polymer in the form of polymerized units comprising: (a) a monomer containing an amide unit of formula (H 2C=CR 1>-CO-NH-R 2>-N +>R 3>R 4>R 5>X ->) (I), (b) a monomer containing an amide unit of formula (H 2C=CR 6>-CO-NR 7>R 8>) (II); (c) acrylic and/or methacrylic acid; and/or (d) further monomers comprising 3-6C ethylenically unsaturated carboxylic acids such as crotonic acid, maleic acid, maleic acid anhydride, fumaric acid, itaconic acid or their salts or half esters, or sulfonic acid compound of formula (H 2C=CR-CO-NH-CR1aR2aR3a-SO 3H) (III) or their salts, preferably alkali metal- and ammonium salts for dispersing solid particles in liquid, preferably aqueous media, is claimed, where the polymer is water-soluble at 20[deg] C, and the amount of the component (c) is not more than 25 wt.%, R 1>H or 1-4C-alkyl; R 2>1-12C alkylene; R 3>-R 5>H, 1-18C-alkyl or phenyl residue; X ->anions from the group of halo, sulfate or alkyl sulfate for hydroxide, phosphate, acetate, formate or ammonium; R 6>R 1>; R 7>, R 8>H, 1-4C alkyl or 3-6C cycloalkyl; and R, R1a-R3a : H or 1-4C alkyl. Provided that R 7>and R 8>are not simultaneously represents a hydrogen atom. Independent claims are included for: (1) the solid particles, produced by contacting carrier particles in an aqueous medium with the polymer, where the polymer remains in the aqueous medium and after treatment the solid particles are separated, dried or left the particles in the medium; and (2) a method for galvanic or autocatalytic metal deposition on metal surfaces, preferably for nickel plating of metal surfaces, comprising adding aqueous nickel solution containing at least one nickel salt, organic acid and inorganic phosphorus compound to an aqueous dispersion of boron nitride particles, and contacting the solution with the metallic surface until dispersion layer from metal and boron nitride particles are separated.