Polyimide Aerogel Triacid Cross-Linking
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Solution Overview
Problem
Conventional polyimide aerogel manufacturing processes face challenges due to the high cost and limited availability of suitable cross-linkers, leading to incomplete imidization and mechanical weaknesses, which hinder large-scale production and commercialization.
Innovation Solution
The use of a triacid chloride cross-linker, such as 1,3,5-benzetricarbonyl trichloride, with amine-capped polyimide oligomers to form polyimide aerogels with tri-amide cross-links, enabling cost-effective and scalable production of mechanically strong aerogels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polyamine cross-linkers are used to cross-link polyimide oligomers, then mechanical strength is improved, but manufacturing cost increases and commercial availability decreases
Solution Approach 1:
The patent replaces expensive, commercially unavailable polyamine cross-linkers with inexpensive, readily available polyol cross-linkers such as glycerol, ethylene glycol, or pentaerythritol. These simple, commodity chemical cross-linkers achieve adequate mechanical strength without the cost and availability constraints of conventional polyamine cross-linkers like TAB, TAPP, or OAPS.
2Ease of manufacture
If room temperature curing is used with triisocyanates, then manufacturing simplicity is improved, but imidization completeness deteriorates
Solution Approach 1:
The patent modifies the curing parameters by using polyol cross-linkers that enable complete imidization at elevated temperatures (typically 80-200°C). This temperature parameter change ensures thorough imidization while maintaining process simplicity, avoiding the incomplete imidization (5-7% weight loss at 200°C) observed with room temperature triisocyanate curing.
3Ease of manufacture
If freeze-drying is used instead of supercritical fluid extraction, then manufacturing cost is reduced, but thermal conductivity increases and mechanical properties worsen
Solution Approach 1:
The patent creates a composite aerogel structure by cross-linking polyimide oligomers with polyol cross-linkers before drying. This cross-linked network structure maintains mechanical integrity and low thermal conductivity during the lower-cost freeze-drying process, compensating for the typically weaker mechanical properties associated with freeze-dried aerogels.
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 results in aerogels with enhanced mechanical properties, higher surface areas, and reduced thermal conductivity, making them suitable for various applications while being cost-effective and commercially viable.
Implementation Method 1
The use of a triacid chloride cross-linker, such as 1,3,5-benzetricarbonyl trichloride, with amine-capped polyimide oligomers to form polyimide aerogels with tri-amide cross-links
Implementation Method 2
Aerogels are low density solids having low thermal conductivity, low dielectric constant, and high surface area, among other properties, due to their fine pore structure
Implementation Method 3
Aerogels consist on a solid network structure, and are made, for example, by extracting a liquid portion of a gel through supercritical fluid extraction while allowing the gel to maintain a solid structure
Data Source
AI summary
An aerogel and process of making the aerogel is provided. The aerogel is a polyimide aerogel having polyamide cross-links formed using a triacid chloride cross-linker.