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SEC-MALDI-TOF mass spectral characterization of a hyperbranched polyether prepared via melt transetherification

Jayakannan, M and Van Dongen, JLJ and Behera, GC and Ramakrishnan, S (2002) SEC-MALDI-TOF mass spectral characterization of a hyperbranched polyether prepared via melt transetherification. In: Journal of Polymer Science Part A: Polymer Chemistry, 40 (24). pp. 4463-4476.

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An AB(2) monomer, 1-(2-hydroxyethoxy)-3,5-bis-(methoxymethyl)-2,4,6-trimethylbenzene, was synthesized from mesitol and melt-polycondensed in the presence of an acid catalyst via a transetherification process at 145-150 degreesC to yield a soluble, moderately high molecular weight hyperbranched polyether. The degree of branching in the polymer was calculated to be 0.78 by a comparison of its NMR spectrum with that of an appropriately designed model compound. The weight-average molecular weight of the hyperbranched polymer was determined to be 64,600 (weight-average molecular weight/number-average molecular weight = 5.2) by size exclusion chromatography (SEC) in CHCl3, with polystyrene standards. The origin of the broad molecular weight distribution, which could either be intrinsic to such hyperbranched structures or be due to structural heterogeneity, was further probed by the fractionation of the samples by SEC and by the subjection of each fraction to matrix-assisted laser desorption/ionization time-of-flight mass spectral analysis. The mass spectral analysis suggested the presence of two primary types of species: one corresponding to the simple branched structure and the other to macrocyclics. Interestingly, from the relative intensities of the two peaks, it was apparent that cyclization became favorable at higher conversions in the melt transetherification process. (C) 2002 Wiley Periodicals, Inc.

Item Type: Journal Article
Publication: Journal of Polymer Science Part A: Polymer Chemistry
Publisher: John Wiley and Sons
Additional Information: Copyright of this article belongs to John Wiley and Sons.
Keywords: hyperbranched;transetherification;degree of branching;MALDI; macrocycles
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 28 Jul 2011 07:25
Last Modified: 28 Jul 2011 07:25
URI: http://eprints.iisc.ac.in/id/eprint/39392

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