Curing chemistry of phenylethynyl-terminated imide oligomers: Synthesis of 13C-labeled oligomers and solid-state NMR studies

• Published in: Journal of polymer science. Part A, Polymer chemistry Vol. 38; no. 19; pp. 3486 - 3497
• Main Authors: Roberts, C. Chad, Apple, Tom M., Wnek, Gary E.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01-10-2000; Wiley
• Subjects: 13C-labeled; Applied sciences; curing; Exact sciences and technology; Organic polymers; phenylethynyl; Physicochemistry of polymers; Polycondensation; polyimides; Preparation, kinetics, thermodynamics, mechanism and catalysts; solid-state NMR; Polyimide; Isotope labelling; Molecular structure; Labelled polymer; Aromatic polymer; NMR spectrometry; Experimental study; Oligomer; Polyaddition; Thermosetting resin; Curing(plastics); Preparation; Crosslinked polymer; Acetylene derivative polymer; Diynic compound
• ISSN: 0887-624X; 1099-0518
• DOI: 10.1002/1099-0518(20001001)38:19<3486::AID-POLA50>3.0.CO;2-1

4‐(Phenylethynyl‐α,β‐13C)phthalic anhydride (PEPA) and 13C‐labeled phenylethynyl‐terminated imide (PETI) oligomers were synthesized, and solid‐state 13C nuclear magnetic resonance (NMR) spectroscopy was used to determine the structure of cured oligomers. Solid‐state 13C NMR spectra were collected before and after thermal curing. Using solid‐state 13C NMR difference spectroscopy, several cure products were identified. The observed 13C NMR resonances were assigned to four different classes of cure products: aromatics, products from backbone addition (substituted stilbenes and tetraphenylethanes), polyenes, and cyclobutadiene cyclodimers. The effects of postcuring and oligomer chain length on the structure of the cured resins were examined. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3486–3497, 2000
Solid‐state 13C NMR was used to determine the structure of cured phenylethynyl‐terminated imide oligomers. The synthesis of 4‐(phenylethynyl‐α,β‐13C) phthalic anhydride and 13C labeled oligomers allowed for the selective observation of chemical shift changes for the ethynyl carbon atoms.