Polymeric systems, imidization studies

Initial investigations of base-catalyzed imidization of polymeric systems, in particular PMDA/ODA based polyfamic alkyl esters), have been difficult due to the insolubility of the polyimide precursor at imidization levels exceeding 40%. Nevertheless, preliminary studies indicate that the base-catalyzed polymer imidization reaction appears to be significantly slower at ambient temperatures as compared to the phthalamide model compounds. It is yet unclear whether this is a direct result of the conformational aspects associated with the polymer chain or solubility considerations arising from the less soluble, partially imidized polymer chain. Since much of the initial work involved IR studies of supported... 

In this paper, recent results of studies performed on the imide derivatives of the trimeric aniline are presented. Films of TANI-polyimide were also prepared and their electrochemical and electrochromic properties were probed. It is shown from this work that well behaved polymeric materials incorporating aniline trimers can be prepared, these trimers can be addressed electrochemically within such polymeric systems and the behavior of the trimer within the polymer does not differ significantly from that within the model compounds. 

The present study reports the synthesis, characterization and thermal reactions of phenyl and carbomethoxy substituted norbornenyl imides. These substrates were designed to model the reactive end-caps of the PMR-15 resin and allow an assessment of the effect that conjugating substituents would have on the high temperature cure of such systems. The effect of these substituents on both monomer isomerization and polymerization is reported and a possible use of the phenyl substituent as a probe of polymer structure is suggested. 

The thermal polymerization of reactive polyimide oligomers is a critical part of a number of currently important polymers. Both the system in which we are interested, PMR-15, and others like it (LARC-13, HR-600), are useful high temperature resins. They also share the feature that, while the basic structure and chemistry of their imide portions is well defined, the mode of reaction and ultimately the structures that result from their thermally activated end-groups is not clear. Since an understanding of this thermal cure would be an important step towards the improvement of both the cure process and the properties of such systems, we have approached our study of PMR-15 with a focus only on this higher temperature thermal curing process. To this end, we have used small molecule model compounds with pre-formed imide moieties and have concentrated on the chemistry of the norbornenyl end-cap (1). 

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