End Capped Poly amide imide

The thermal integrity and solvent resistance can he greatly enhanced hy capping the amide imide hackhones with monomers that can be cross-linked.  

If an excess of the diamine is used, the free amino end groups can be end capped, e.g., with nadic anhydride or maleic anhydride. These materials can be crosslinked via the reactive vinyl group by a thermosetting reaction. 

Synthesis methods of such end capped materials have been developed in which diisocyanates and aromatic anhydride acids are used. It has been proposed that a wide variety of oligomeric materials with different functional groups can be blended to tailor the properties of the cured 

An unsaturated PAI has been prepared from l,5-bis(3-aminophenyl)-l,4-pentadien-3-one and 2-(4-carboxyphenyl)-1,3-dioxoisoindoline-5-carbox-ylic acid. Thionyl chloride serves to activate the acid group as intermediate acid chloride. As cocatalyst, lithium chloride is used. The reaction runs at 0-5 °C. The polymers exhibit a glass transition temperature of 220°C. Crosslinking of the polymer can be achieved with dibenzoylperox-ide. Then the transition temperature raises up to 235°C. 

Blends of a PAI and poly(aryl ether ketone) exhibit improved solvent resistance and hydrolytic stability. Blends of sulfonated poly(ether ether ketone) and PAI have been tested as membrane materials for direct methanol fuel cells. Miscible blends can be obtained. Blends of poly(urethane)s (PU)s and PAI, as the minor component have been reported for membrane applications. The resulting membranes are immiscible. Phase separation occurs when the amount of PU decreases. 

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