Metal Oxide-Silica Aerogel Shrinkage Suppression
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Solution Overview
Problem
The existing methods for preparing metal oxide-silica composite aerogels suffer from a severe shrinkage phenomenon during drying, leading to reduced specific surface area and pore volume, making them unsuitable for industrial applications and requiring excessive organic solvents, which increases production costs.
Innovation Solution
A method involving a two-step structural strengthening process, where a metal ion solution is added to a first water glass solution for a primary reaction, followed by a second water glass solution and acid catalyst for a secondary reaction, and then drying, with specific pH and concentration adjustments to suppress shrinkage and enhance porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a metal oxide-silica composite aerogel is prepared by conventional drying methods, then the preparation process is simple, but the structure collapses due to severe shrinkage phenomenon, resulting in reduced specific surface area and pore volume
Solution Approach 1:
The patent applies preliminary action by introducing a surface modifier (such as hexadecyltrimethylammonium bromide) to the wet gel before drying. This modifier forms a protective layer on the gel surface that prevents capillary forces from causing shrinkage during subsequent drying, thereby preserving the aerogel's porous structure and high specific surface area while maintaining preparation simplicity
Solution Approach 2:
The surface modifier acts as an intermediary substance between the gel network and the drying environment. It mediates the drying process by reducing surface tension and preventing direct contact between air and gel pores, thus avoiding the shrinkage phenomenon that would otherwise collapse the delicate aerogel structure
2Manufacturing precision
If organic solvent washing is performed to suppress shrinkage phenomenon, then shrinkage is reduced, but a large amount of organic solvent is required, reducing economic efficiency
Solution Approach 1:
The patent replaces expensive and environmentally problematic organic solvents with water as the washing medium. Water is inexpensive, non-flammable, and environmentally friendly, yet it effectively suppresses shrinkage when used in combination with the surface modifier approach, thereby reducing both cost and solvent consumption
Solution Approach 2:
The patent changes the chemical composition parameters of the washing solution by using water instead of organic solvents. This parameter change, combined with the surface modifier treatment, alters the surface properties of the gel to prevent shrinkage during water-based washing and drying, achieving the same effect with a more economical and safer substance
3Weight of moving object
If silica aerogel is prepared with high porosity (90-99.9%), then ultra-lightweight and ultra-insulation properties are achieved, but mechanical strength is reduced making it vulnerable to structural collapse
Solution Approach 1:
The patent creates a composite material system by incorporating metal oxide particles (such as TiO2, ZnO, or Al2O3) into the silica aerogel matrix. This composite structure provides mechanical reinforcement to the ultra-lightweight aerogel, preventing structural collapse during handling and application while preserving the high porosity (90-99.9%) that enables ultra-lightweight and ultra-insulation properties
Solution Approach 2:
The metal oxide particles are distributed throughout the silica aerogel matrix, providing localized reinforcement at critical points where stress concentration occurs. This local quality enhancement strengthens the overall structure without significantly increasing density, maintaining the ultra-lightweight characteristic while improving mechanical strength
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
This approach effectively prevents structural collapse during drying, resulting in metal oxide-silica composite aerogels with high specific surface area, high pore volume, and reduced production costs, suitable for industrial applications.
Implementation Method 1
preparing a silica sol by hydrolysis of tetra ethyl ortho silicate (TEOS) or water glass with an acid catalyst
Implementation Method 2
adding a basic catalyst thereto, and performing a condensation reaction to prepare a hydrophilic wet gel
Implementation Method 3
performing solvent substitution in which the aged wet gel is put in an organic solvent to substitute water present in the wet gel with an organic solvent
Implementation Method 4
preparing a hydrophobic wet gel by adding a surface modifier to the solvent-substituted wet gel and performing a modification reaction for a long period of time
Implementation Method 5
preparing a hydrophobic silica aerogel by washing and drying the hydrophobic wet gel
Implementation Method 6
pyrolyzing the aerogel
Data Source
AI summary
The present invention relates to a method of preparing an ultra-light metal oxide-silica composite aerogel having high specific surface area and high pore volume and a metal oxide-silica composite aerogel prepared thereby. The preparation method according to the present invention may not only have good economic efficiency because production costs are relatively reduced in comparison to the related art, but may also effectively prevent the collapse of a pore structure by suppressing a shrinkage phenomenon during drying, and thus, a metal oxide-silica composite aerogel having ultra-light properties as well as high porosity characteristics, such as high specific surface area and high pore volume, may be prepared.