When O,O′‐Bistrimethylsilyl catechol (BTSC) was polycondensed with adipoyl chloride in o‐dichlorobenzene the 10‐membered cyclic monomer was the main reaction product regardless of the concentration. Even the polycondensation in bulk yielded the macrocyclic monomer as the main product. Polycondensations of free catechol yielded similar results. Polycondensations of catechol or BTSC with suberoyl chloride, sebacoyl chloride, and decane‐1,10‐dicarbonyl chloride in concentrated solutions or in bulk yielded cyclic oligoesters as the main reaction products whereas linear oligoesters or polyesters were a minority. Polycondensations of BTSC with the longer diacid dichlorides in refluxing o‐dichlorobenzene under high dilution yielded the 12–14‐membered cyclic monomers as the main products. The molecular weights and the cyclic structure of all reaction products were characterized by mass spectrometery, fast‐atom bombardment (FAB) or MALDI‐TOF mass spectrometry. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3861–3870, 1999

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.