Aerogel Precursor Hydrophobicity Thermal Stability
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Solution Overview
Problem
Existing aerogel synthesis methods face challenges in achieving high temperature durability due to moisture penetration and oxidation of surface hydrophobizing agents, leading to decreased thermal stability.
Innovation Solution
An alkoxydisiloxane-based prepolymer with a hydrophobic sol-gel forming agent is used to create an aerogel precursor, allowing for uniform hydrophobic pore formation and enhanced thermal stability by controlling the degree of hydrolysis and molecular weight, resulting in an aerogel with improved heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface hydrophobization is performed after wet gel preparation, then hydrophobicity is achieved, but reaction efficiency is low and large quantities of hydrophobizing agent are required
Solution Approach 1:
The patent applies preliminary action by incorporating the hydrophobizing agent during the sol-gel reaction phase rather than performing surface hydrophobization after wet gel preparation. The hydrophobizing agent is mixed with the precursor solution before gelation occurs, allowing the hydrophobic modification to happen concurrently with the network formation process. This preliminary incorporation ensures that the hydrophobic groups are distributed throughout the gel matrix during the reactive state, improving reaction efficiency and reducing the quantity of agent required.
2Reliability
If large quantities of surface hydrophobizing agent are used, then hydrophobicity is enhanced, but high temperature durability decreases due to oxidation
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration and molecular structure of the hydrophobizing agent. Instead of using large quantities of simple hydrophobic groups, the invention employs a specifically designed hydrophobizing agent with controlled concentration (0.1-10 wt% of total precursor) and specific molecular weight (60-140 Da for the repeating unit). This parameter optimization achieves sufficient hydrophobicity while minimizing the total amount of organic material present, thereby reducing susceptibility to oxidation at high temperatures and improving long-term durability.
3Ease of manufacture
If conventional precursors like TEOS are used, then aerogel synthesis is straightforward, but thermal stability at high temperatures is insufficient
Solution Approach 1:
The patent applies composite materials by creating a hybrid aerogel system that combines conventional silica network formers (TEOS, TMOS) with organometallic precursors containing hydrophobic functional groups. The composite precursor system includes both inorganic network-building components and organic hydrophobizing components in a unified molecular structure. This composite approach allows the aerogel to maintain the structural integrity and ease of synthesis associated with conventional silica aerogels while simultaneously achieving enhanced thermal stability and hydrophobicity through the integrated organic functionality.
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 approach results in an aerogel with enhanced high-temperature thermal stability, low thermal conductivity, and improved physical properties such as low tap density and high specific surface area, making it suitable for insulation and other applications.
Implementation Method 1
preparing an alkoxydisiloxane-based prepolymer by hydrolyzing and polycondensation reacting an alkoxysilane-based compound
Implementation Method 2
polycondensation reacting an alkoxysilane-based compound
Implementation Method 3
reacting the alkoxydisiloxane-based prepolymer with a hydrophobic sol-gel forming agent
Data Source
Figure 1a~1b
Figure 2a~2b
AI summary
The present disclosure provides an aerogel precursor including an alkoxydisiloxane-based prepolymer and having a functional group derived from a hydrophobic sol-gel forming agent of the following Chemical Formula 1 on a surface thereof, and therefore, capable of enhancing high temperature thermal stability of an aerogel providing hydrophobic pores having uniform pore size distribution when preparing an aerogel, and an aerogel prepared using the same: (in Chemical Formula 1, M, R, R1 to R4 are the same as defined in the specification.)