Core/Shell Nanoparticle Synthesis via Tubular Membrane Reactor
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Solution Overview
Problem
Current methods for producing core/shell nanoparticles face challenges such as lattice strains between core and shell materials, leading to irregular shapes and reduced quantum yield, and are not suitable for continuous production or large-scale quantities, resulting in variations in product properties and broad size distributions.
Innovation Solution
A method involving a tubular reactor where core nanoparticles are dispersed in a solvent, and shell starting materials are selectively mixed and continuously fed through the reactor, forming a shell around the core with a transition zone composed only of core and shell components, minimizing lattice strain and suppressing unwanted nucleation, thereby achieving a narrow particle size distribution and high quantum yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If core and shell materials are directly combined to form core/shell nanoparticles, then the quantum yield increases due to passivation, but lattice strains arise from mismatched lattice constants leading to irregular shapes and reduced quantum yield
Solution Approach 1:
The patent introduces a transition zone with gradient composition between the core and shell materials. This transition zone has locally varying material properties, with the composition gradually changing from core material to shell material, thereby reducing lattice strain at the interface while maintaining the passivation effect on the core surface.
Solution Approach 2:
The transition zone acts as an intermediary layer between the core and shell materials. It mediates the lattice mismatch by providing a gradual compositional transition, reducing the abrupt interface strain that would otherwise occur between directly contacting core and shell materials with different lattice constants.
2Manufacturing precision
If batch processes are used for producing core/shell nanoparticles, then product properties can be controlled, but the production is not suitable for continuous production or large-scale quantities, resulting in variations in product properties
Solution Approach 1:
The patent describes a continuous flow process where reactants are continuously fed through a microfluidic reactor system. The core and shell materials are continuously synthesized and assembled in a streamlined process, enabling large-scale production while maintaining consistent product properties through controlled flow conditions and uniform mixing.
3Ease of manufacture
If shell starting materials are mixed together before adding to core dispersion, then the mixing is simple, but unwanted nucleation occurs leading to broad size distributions
Solution Approach 1:
The patent segments the addition of shell starting materials into separate streams that are introduced at different locations or times within the microfluidic reactor. This prevents premature mixing and unwanted nucleation while maintaining controlled shell growth on the core particles, achieving both simple operation and narrow size distribution.
Solution Approach 2:
The patent prepares shell starting material solutions separately and pre-mixes them with appropriate ligands or stabilizers before introduction to the core dispersion. This preliminary preparation ensures that the shell materials are ready for controlled deposition without causing unwanted nucleation, combining ease of manufacture with precise size control.
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 enables the production of core/shell nanoparticles with minimized lattice strain, narrow particle size distribution, and enhanced luminescence properties, allowing for continuous and efficient production of high-quality nanoparticles with consistent properties.
Implementation Method 1
The dispersion of particles from the core material produced in step a) contains at least one starting material for the core material... the reaction of the starting materials for the shell material in the reaction zone (10) to form a shell around the nanoparticles from the core material
Data Source
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AI summary
The present invention relates to a method for continuously producing core/shell nanoparticles, which comprise a core of a core material, preferably of a semiconductor material, and a shell of a shell material, preferably of a semiconductor material, in which selected starting substances for the shell material mixed together with a dispersion of nanoparticles of the core material are passed continuously through a reaction zone of a tubular reactor, and further starting substances for the shell material are fed in at two or more points, preferably by way of a tubular membrane, to the reaction zone of the tubular reactor, and the starting substances for the shell material react in the reaction zone to form a shell around the nanoparticles of the core material. The invention also relates to the tubular reactor with membrane and to the use thereof for the continuous synthesis of core/shell nanoparticles. The invention also relates to core/shell nanoparticles, which comprise a core of a core material, preferably a first semiconductor material, and an outer shell of a shell material, characterized in that between the core and the shell there is only one layer of a transitional zone, in which the proportion of core material gradually decreases in the direction of the shell and at the same time the proportion of the shell material gradually increases.