Oligomeric Phthalonitrile Monomers for Low-Temperature Processing
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Solution Overview
Problem
Current phthalonitrile polymers have high melting points and initial high viscosities, making them unsuitable for low-temperature processing and autoclave-free composite fabrication, and they lack a large processing window for controlling curing reactions.
Innovation Solution
Synthesis of low melting oligomeric phthalonitrile monomers with multiple aromatic ether moieties and alkenyl linkages, derived from renewable phenols like resveratrol and eugenol, which can polymerize to form thermosets with controlled glass transition temperatures and high thermal stability, allowing for processing above 70°C without an autoclave and using cost-effective methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional phthalonitrile polymers are used, then high thermal stability and high char yield are achieved, but high melting points and high viscosities prevent low-temperature processing
Solution Approach 1:
The patent segments the polymer structure by introducing oligomeric intermediates with controlled molecular weights and aromatic ether moieties. This segmentation allows the material to be processed at lower temperatures while maintaining the final crosslinked network's thermal stability. The oligomeric phthalonitrile monomers have lower melting points than conventional polymers, enabling low-temperature processing.
Solution Approach 2:
The patent changes key structural parameters by incorporating alkenyl linkages and controlling the degree of polymerization in the oligomeric intermediates. These parameter changes reduce the melting point and viscosity of the material during processing, while the final cured product maintains high thermal stability through crosslinking.
2Temperature
If conventional phthalonitrile polymers are used, then high thermal stability is achieved, but high initial viscosities limit processing options
Solution Approach 1:
The patent introduces dynamic control over viscosity through the use of oligomeric intermediates with adjustable molecular weights. The material transitions from a low-viscosity oligomeric state during processing to a high-strength crosslinked network after curing. This dynamic property change simplifies processing by allowing the material to be manipulated in a low-viscosity state.
3Stability of the object's composition
If conventional phthalonitrile polymers are used, then high aromatic content is achieved, but lack of processing window prevents autoclave-free fabrication
Solution Approach 1:
The patent performs preliminary action by pre-synthesizing oligomeric phthalonitrile monomers with controlled aromatic content and molecular weight. These pre-prepared oligomers have optimized properties that allow direct processing without requiring high aromatic content during the processing stage. The aromatic units are then locked into place during the curing stage, maintaining high aromatic content in the final product while enabling simplified fabrication.
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 resulting thermosets exhibit excellent thermal and oxidative stability up to 375°C, superior flammability resistance, and a large processing window, enabling the fabrication of complex composite components using methods like resin transfer molding and filament winding.
Implementation Method 1
reacting a polyphenol with a base
Implementation Method 2
The phthalonitrile monomers polymerize through the cyano groups, with the aid of an appropriate curing agent, to yield a crosslinked polymeric network
Implementation Method 3
the high aromatic content of the thermoset affords a high char yield (>80%) when pyrolyzed to 1000° C. under inert conditions
Data Source
AI summary
A method of making an organic salt comprising: reacting a polyphenol with a base and optionally a dihaloaromatic compound. The polyphenol is resveratrol; dihydroresveratrol; 4,4′-(but-2-ene-1,4-diyl)bis-2-methoxyphenol; 4,4′-(1,4-butane-diyl)bis-2-methoxyphenol; 1-ethyl-2-methyl-3-(4-hydroxyphenyl)-5-hydroxyindane; 4,4′-(ethane-1,1-diyl)diphenol; 5,5′-methylenebis(2-methoxy-4-methylphenol); 4,4′-methylenebis(5-isopropyl-2-methylphenol); 4,4′-(1-ethyl-2-methyl-1,3-propanediyl)bisphenol; or 5,5′-(ethane-1,1-diyl)bis(2-methoxy-4-methylphenol. The dihaloaromatic compound if present comprises a carbonyl group, a sulfonyl group, a sulfinyl group, or a phosphoryl group. There is a molar excess of the hydroxy groups of the polyphenol relative to halo groups of the dihaloaromatic compound if present. The corresponding phthalonitrile monomers and thermosets made from the organic salts are disclosed.