Solid‐State ¹³C‐NMR spectral evidence for charge transfer complex formation in aromatic diimides and dianhydrides

Abstract

Solution and solid‐state proton decoupled 13C‐NMR spectra were determined on two diimides derived from 4, 4′‐oxydiphthalic anhydride. Comparison of the individual diimide spectra to that of a mixture of the two diimides indicates that ordering of these materials occurs in the solid state via charge transfer complex formation. A similar study was conducted using two isomeric dianhydrides, 4, 4′‐isophthaloyldiphthalic anhydride (IDPA) and 4, 4′‐terephthaloyldiphthalic anhydride (TDPA). The solution spectra of these compounds are similar and are those which would be expected for these compounds. However, their solid state spectra differ from each other. The solid‐state spectrum of TDPA resembles its solution spectrum, whereas, that of IDPA differs greatly from its solution spectrum and indicates charge transfer complex formation occurs with this molecule. This difference is explained in terms of the stereochemistry of the two isomeric dianhydrides.

A comparison of homopolymer and block copolymer structure in 6FDA-based polyimides

“…The maximum standard errors are AE0.05 nm 3 for the volumes, AE0.08 kJ mol À1 monomer À1 for the energies and AE0.02 J 1/2 cm À3/2 for the Hildebrand solubility parameters (dianhydrides) moieties. 10,103,104 The corresponding diaminediamine and anhydride-diamine g inter (r) plots are displayed in Fig. 6.…”

13C CP–MAS NMR study of absorbed water in polyimide film

“…'~-'~ The exact nature of this interaction is not completely understood, but in Kapton alignment should occur in a face-to-face manner through electron-poor imide rings with the relatively electron-rich nitrogen and oxygen-substituted ring of the oxydianiline monomer. 17 In this type of "layered" charge transfer complexation, approach of a translating species cannot occur above or below the plane of the imide ring, and it is obvious that the presence of water hydrogen bonded to the carbonyl within the imide ring plane could significantly prevent the approach of any species to the carbonyl carbon through steric factors. In addition, since the water molecule is relatively less mobile at the carbonyl, this steric effect would be effective for long periods of time on the NMR T1 time scale, and the effect should be observable by NMR relaxation measurements.…”

Relaxation Dynamics of Thin Matrimid 5218 Films in Organic Solvents

“…This is in agreement with literature, where it is suggested slight cross-linking occurs via the formation of charge-transfer complexes between the benzene rings and the imide rings, allowing the transfer of π-electrons. 39,46−48…”