Silver Nanoplatelet Synthesis for Colloidal Stability
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Solution Overview
Problem
Existing methods for synthesizing silver nanoplatelets with high colloidal stability and uniform size distribution are not economically efficient or reproducible at high silver concentrations.
Innovation Solution
The synthesis of silver nanoplatelets with a mean diameter of 20 to 70 nm and a mean thickness of 5 to 30 nm, using surface stabilizing agents that provide high colloidal stability and uniform size distribution, is achieved through a process involving a silver precursor mixture and a reducing agent mixture, with optional additional stabilization agents to maintain optical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If existing synthesis methods are used to produce silver nanoplatelets, then production can be achieved, but colloidal stability and uniform size distribution are not maintained at high silver concentrations
Solution Approach 1:
The patent introduces specific stabilizing agents (surfactants, polymers, or ligands) as intermediary substances that mediate between the silver nanoplatelets and the surrounding medium. These stabilizing agents adsorb onto the nanoplatelet surfaces, providing electrostatic or steric stabilization that prevents aggregation even at high concentrations, thus resolving the contradiction between quantity and stability
Solution Approach 2:
The patent optimizes multiple parameters including pH, temperature, reducing agent concentration, and stabilizing agent ratio to achieve high colloidal stability at high silver concentrations. By systematically adjusting these parameters, the synthesis process maintains nanoplatelet dispersion and prevents aggregation, resolving the contradiction between quantity of substance and stability
2Quantity of substance
If existing synthesis methods are used to produce silver nanoplatelets, then production can be achieved, but uniform size distribution is not obtained
Solution Approach 1:
The patent employs seed-mediated growth where pre-formed small silver nanoplatelets (seeds) are used to initiate controlled growth. This preliminary action ensures that all nanoplatelets start from a uniform size baseline, enabling precise control over final size distribution even when producing large quantities, thus resolving the contradiction between quantity and manufacturing precision
Solution Approach 2:
The synthesis employs periodic addition of reducing agents or controlled multi-stage reduction processes. This periodic action allows gradual and uniform growth of nanoplatelets, preventing burst nucleation that would lead to size polydispersity. The controlled periodic addition ensures uniform size distribution while maintaining high silver concentration utilization
3Productivity
If high silver concentrations are used to improve productivity, then production efficiency increases, but optical stability upon storage is compromised
Solution Approach 1:
The patent uses stabilizing agents as intermediaries that form protective layers around nanoplatelets, preventing oxidation and aggregation that would compromise optical properties. This mediation allows high concentration formulations to maintain optical stability during storage, resolving the contradiction between productivity and reliability
Solution Approach 2:
The patent employs inert atmospheres (nitrogen or argon) during synthesis and storage to prevent oxidation of silver nanoplatelets. By creating an inert environment, the optical properties remain stable even at high concentrations during storage, resolving the contradiction between productivity and reliability
4Quantity of substance
If conventional synthesis approaches are used, then production can proceed, but economic efficiency is not achieved at high silver concentrations
Solution Approach 1:
The patent optimizes synthesis parameters to maximize silver utilization efficiency and minimize waste. By adjusting pH, temperature, and reagent ratios, the process achieves high yield at high silver concentrations without requiring expensive additional materials or complex purification steps, thus resolving the contradiction between quantity and ease of manufacture
Solution Approach 2:
The patent employs self-assembly and self-stabilization mechanisms where the nanoplatelets themselves contribute to their own stabilization through controlled aggregation or surface chemistry. This self-service approach reduces the need for additional stabilizing agents and complex processing steps, improving economic efficiency while maintaining high silver concentration
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 resulting silver nanoplatelets exhibit high colloidal stability, uniform size distribution, and maintain their optical properties upon storage and heat exposure, making them suitable for use in security products and printing inks.
Implementation Method 1
combining the metal precursor mixture with the reducing agent mixture so as to allow the metal precursor compound to react with the reducing agent, thereby synthesizing the metal nanoparticles
Implementation Method 2
The aqueous catalyst solution comprises nanoparticles of one or more metal chosen from silver, gold, platinum, palladium, iridium, copper, aluminum, cobalt, nickel and iron, and one or more stabilizing compounds chosen from gallic acid, gallic acid derivatives and salts thereof
Data Source
AI summary
The present invention relates to compositions, comprising silver nanoplatelets, wherein the mean diameter of the silver nanoplatelets, present in the composition, is in the range of 20 to 70 nm with standard deviation being less than 50% and the mean thickness of the silver nanoplatelets, present in the composition, is in the range of 5 to 30 nm with standard deviation being less than 50%, wherein the mean aspect ratio of the silver nanoplatelets is higher than 1.5, a process for its production, printing inks containing the compositions and their use in security products. The highest wavelength absorption maximum of the population of all silver nanoplatelets in the composition being within the range of 450 to 550 nm. A coating, comprising the composition, shows a red, or magenta color in transmission and a greenish-metallic color in reflection.