Stable Nanodiamond Dispersion via pH and Conductivity Control
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Solution Overview
Problem
Existing methods for producing nanodiamond dispersions result in unstable colloids with large particle diameters and low concentrations, prone to aggregation over time, especially at high concentrations.
Innovation Solution
A method involving the purification of detonation nanodiamond aggregates by adjusting the pH to 8-10.5 and electric conductivity to 300 µS/cm or less, followed by deaggregation using a bead mill or ultrasonic treatment, to produce a stable single-nano-sized nanodiamond dispersion with a concentration of 4 weight percent or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nanodiamond particles are produced by detonation technique and dispersed in water, then high concentration dispersion can be achieved, but the particles undergo aggregation over time and particle diameter increases
Solution Approach 1:
The patent applies preliminary action by adjusting the pH to 8-10.5 and electric conductivity to 300 µS/cm or less before dispersion. This pre-treatment of the nanodiamond aggregates creates optimal conditions for stable high-concentration dispersion, preventing aggregation before it occurs. The pH adjustment and conductivity control are performed in advance to ensure long-term stability.
Solution Approach 2:
The patent changes key parameters including pH (adjusted to 8-10.5), electric conductivity (reduced to 300 µS/cm or less), and uses deaggregation treatment. These parameter changes transform the nanodiamond aggregates into a stable dispersion state that maintains both high concentration and long-term stability without aggregation.
2Manufacturing precision
If bead mill or ultrasonic homogenizer is used to pulverize nanodiamond aggregates, then particle size is reduced to single-nano-sized, but the concentration becomes low
Solution Approach 1:
The patent applies partial action by using deaggregation treatment (bead mill or ultrasonic homogenizer) selectively on the nanodiamond aggregates under controlled conditions. Rather than excessive pulverization that would dilute the dispersion, the treatment is applied just enough to achieve single-nano-sized particles while maintaining high concentration through the optimized pH and conductivity parameters.
3Duration of action of stationary object
If nanodiamond dispersion is left stand at room temperature for long time, then aggregation gradually occurs and particle diameter increases, but maintaining stability requires additional control measures
Solution Approach 1:
The patent applies preliminary action by adjusting the pH to 8-10.5 and electric conductivity to 300 µS/cm or less before storage. This pre-treatment creates a stable environment that prevents aggregation during long-term storage at room temperature, allowing the dispersion to maintain its properties over extended periods without additional control measures.
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 achieves excellent dispersion stability even at high concentrations, preventing aggregation and maintaining particle size stability over time, resulting in a highly stable single-nano-sized nanodiamond dispersion.
Implementation Method 1
pulverized using a disperser such as a bead mill or an ultrasonic homogenizer
Implementation Method 2
The agglutinate structure was broken up using a bead mill
Data Source
AI summary
A suspension of nanodiamond aggregates according to the present invention is a suspension of detonation nanodiamond aggregates. The suspension has such a pH and an electric conductivity as to meet one of conditions (1) and (2) as follows. (1) The suspension has a pH of 4 to 7 and an electric conductivity of 50 µS/cm or less per weight percent of the solids concentration of the suspension; and (2) the suspension has a pH of 8 to 10.5 and has an electric conductivity of 300 µS/cm or less per weight percent of the solids concentration of the suspension.