Cyclic alkyl ketene oligomers

Abstract

ABSTRACTTwo alkyl ketene oligomers (AKOs) with almost 100% purities were prepared in high yields of 80–90% from palmitic acid chloride and alkyl ketene dimer (prepared from palmitic acid chloride) in the presence of amine promoters. Two AKOs thus obtained had quite similar molecular weights (1000–10,000), carbon/hydrogen contents, X‐ray diffraction patterns, solution‐state 13C‐NMR spectra, and water‐contact angles. However, two AKOs had different size‐exclusion chromatograms, differential scanning calorimetric curves, FTIR spectra, and solution‐state 13C‐NMR spectra for 13C‐labeled AKOs. Based on the 13C‐NMR spectra of 13C‐unlabeled AKOs, AKOs are likely to have cyclic structures, thus having the limited molecular weights of <10,000. The results of FTIR spectra and 13C‐NMR spectra of 13C‐labeled AKOs indicated that three different repeating units were linked with various molar ratios and various connection patterns and combinations, constituting the cyclic AKOs. As a result, 13C‐NMR spectra of 13C‐labeled AKOs showed quite a number of carbon signals due to various 13CO and 13CC structures present in AKOs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3668–3673, 2013