Fluorescence of Copoly(ester‐imide)s Containing 2,6‐Naphthoate Units

Abstract

The intrinsic fluorescence of copoly(ester‐imide)s is used to obtain information about the existence of sandwich like arrangement of aromatic units. The copoly(ester‐imide) investigated herein contains tert‐butylhydroquinone, N‐(4‐carboxyphenyl)trimellitimide and 2,6‐naphthoate moieties. Depending on the excitation wavelength, different sandwich like arrangements are observed by the change of the fluorescence. Identification of the different interacting units was performed by comparing the copoly(ester‐imide) fluorescence with the fluorescence of different low molecular weight model substances representing different parts of the polymer chain. Ground‐state stable dimer formation between the imide parts and the naphthoate moieties, as well as mixed ground‐state stable complex formation between these parts was observed. All measurements were performed in 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) solutions.

Charge Transfer Interactions of N-(4-Carboxyphenyl)trimellitimide Dibutyl Ester

“…The solvent HFIP was used because it is a good solvent for copoly(ester imides). 11 The absorption band observed around 310 nm is shown in a magnified representation on top of Figure 2. In this magnified view, a fine structure and a red shift with increasing solvent polarity is visible.…”