Porous Silica Core-Shell Microparticles for Chromatography
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Solution Overview
Problem
Current methods for producing sub-2µm silica core-shell microparticles for chromatography applications face challenges in achieving the desired pore size and structure, leading to inefficiencies in liquid chromatography and other applications.
Innovation Solution
A process involving the growth of a porous silica shell on a non-porous silica core using a mixed surfactant solution under basic pH conditions, followed by hydrothermal treatment and calcination, to create core-shell microparticles with controlled pore size and structure, utilizing a combination of cationic and non-ionic surfactants and tri-block co-polymers for steric stabilization and pore expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fused core technology is used to create porous shell, then porous structure is achieved, but high temperature treatment is required which complicates the process
Solution Approach 1:
The patent changes the pH parameter from neutral/basic to acidic conditions, enabling porous shell formation without high temperature treatment. The acidic pH facilitates direct dissolution of silica to create porosity, eliminating the need for thermal processing steps while achieving the desired porous structure.
Solution Approach 2:
The patent replaces the thermal mechanism (high temperature treatment) with a chemical mechanism (acidic pH dissolution). Instead of using heat to create pores, the process uses acidic conditions to chemically dissolve silica and form the porous structure, substituting one physical-chemical mechanism for another more efficient one.
2Productivity
If sub-2µm particle size is achieved, then chromatography efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs self-assembly mechanisms where surfactants and silica precursors spontaneously organize into micellar structures that template the porous shell formation. This self-organizing process naturally produces uniform particle sizes and structures without requiring precise external control, enabling sub-2µm particles to be manufactured with consistent dimensions through intrinsic self-regulation rather than complex external precision control.
3Area of stationary object
If porous shell thickness is increased, then surface area is improved, but back pressure increases
Solution Approach 1:
The patent creates a porous shell structure where the porous network provides high surface area while maintaining open pathways for fluid flow. The interconnected pores allow mobile phase to pass through with minimal resistance, decoupling the relationship between surface area and back pressure that exists in dense non-porous structures. This enables thick shells to provide high surface area without proportionally increasing back pressure.
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 process effectively produces core-shell microparticles with a thick porous shell, optimized pore size, and high surface area, enhancing their performance as packing materials in liquid chromatography by reducing back pressure and improving separation efficiency.
Implementation Method 1
DE-19530031 (Unger et al) describes a process for forming templated core-shell sub-2μm silica particles comprising a porous layer on the surface of a non-porous silica core by sol-gel polycondensation of an alkytrialkoxysilane in an ammonia-water solution
Implementation Method 2
hydrothermally treating the particles of (a) in an oil-in-water emulsion system to expand the size of the pores in the silica shell
Implementation Method 3
calcining the particles of (b) to remove residual surfactants
Implementation Method 4
utilizing a combination of cationic and non-ionic surfactants and tri-block co-polymers for steric stabilization and pore expansion
Implementation Method 5
The process for making SBA-15 particles employs a non-ionic surfactant (templating agent) of amphiphilic block co-polymer to direct the pore formation
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
Silica core - shell microparticles are prepared by growing a porous silica shell from a silica precursor onto the surface of non- porous silica particle dispersed in a mixed surfactant solution under basic pH conditions. The particles are hydrothermally treating in an oil-in-water emulsion system and the particles are calcined to remove residual surfactants. Optionally, the particles o may be base etched to expand the size of the pores in the silica shell. Core-shell silica particle with an ordered mesoporous layer are produced.