Zeta Negative Nanodiamond Dispersion pH Control
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Solution Overview
Problem
Current methods for producing zeta negative single digit carboxylated nanodiamond dispersions face challenges due to agglomeration issues during beads milling, leading to clogging and reduced zeta potential, which limits the production of high-concentration, stable dispersions with optimal zeta potential values.
Innovation Solution
Adjusting the pH of the zeta negative carboxylated nanodiamond suspension to a neutral to alkaline region using base additives prevents the reduction of carboxylic acid functions to hydroxyl groups during beads milling, allowing for the production of highly zeta negative single digit carboxylated nanodiamond dispersions with high concentrations and stable zeta potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If beads milling is performed on carboxylated nanodiamond suspension without pH adjustment, then nanodiamond particles can be processed, but carboxylic acid functions are reduced to hydroxyl groups causing agglomeration and clogging
Solution Approach 1:
The patent applies preliminary action by adjusting the pH of the nanodiamond suspension to a neutral or alkaline range (pH 7-14) before performing beads milling. This pre-adjustment prevents the reduction of carboxylic acid functions to hydroxyl groups during milling, thereby maintaining surface functionality and preventing agglomeration while enabling successful milling processing.
2Stability of the object's composition
If pH is adjusted to neutral or alkaline region before beads milling, then carboxylic acid functions are protected from reduction, but additional processing step is required
Solution Approach 1:
The patent applies parameter changes by modifying the pH parameter of the nanodiamond suspension from acidic to neutral or alkaline range before beads milling. This parameter adjustment fundamentally changes the chemical environment to prevent unwanted reduction reactions, protecting carboxylic acid functions while enabling successful milling. The pH adjustment is a simple, well-established chemical parameter control that adds minimal complexity.
3Quantity of substance
If nanodiamonds are used in agglomerated form, then filler loading can be increased, but application performance deteriorates due to agglomeration
Solution Approach 1:
The patent applies preliminary anti-action by taking measures before agglomeration can occur. By adjusting the pH to neutral or alkaline conditions before beads milling, the carboxylic acid groups on nanodiamond surfaces are preserved in their deprotonated, negatively charged state. This creates electrostatic repulsion between particles that prevents agglomeration during and after processing, enabling high concentrations to be maintained without performance deterioration.
4Stability of the object's composition
If zeta potential is not maintained at high negative values, then dispersion stability is reduced, but production cost and complexity increase
Solution Approach 1:
The patent applies parameter changes by controlling the pH parameter to maintain high negative zeta potential values (> -50 mV). By adjusting and maintaining pH in the neutral to alkaline range, the carboxylic acid groups remain deprotonated, creating strong negative surface charges that provide electrostatic stabilization. This simple pH control approach efficiently maintains both high zeta potential and dispersion stability without requiring complex additional processes.
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 method effectively prevents agglomeration and clogging, enabling the production of zeta negative single digit carboxylated nanodiamond dispersions with zeta potentials over -50 mV and concentrations above 2 wt-%, ensuring stability and optimal performance in various applications.
Implementation Method 1
Adjusting the pH of the zeta negative carboxylated nanodiamond suspension to a neutral to alkaline region using base additives
Implementation Method 2
subjecting the pH adjusted suspension to beads milling
Implementation Method 3
The zeta potential indicates the degree of repulsion between adjacent, similarly charged particles in dispersion
Data Source
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AI summary
The present invention relates to a method for producing zeta negative single digit carboxylated nanodiamond dispersion. The method comprises adjusting pH of zeta negative carboxylated nanodiamond suspension to at least 7, and subjecting the pH adjusted suspension to beads milling. The present invention further relates to zeta negative single digit carboxylated nanodiamond dispersion comprising zeta negative single digit carboxylated nanodiamond particles and a liquid medium, wherein zeta potential of the zeta negative single digit carboxylated nanodiamond dispersion is over -37 mV measured at pH over 7, zeta negative single digit carboxylated nanodiamond particle concentration in the dispersion is over 2 wt-% and D90 average primary particle size distribution of the zeta negative single digit carboxylated nanodiamond particles is from 2 nm to 12 nm.