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Characterization of Commercial Aliphatic Hyperbranched Polyesters
Authors: Žagar Ema | Žigon Majda | Podzimek Štěpán
Year: 2006
Type of publication: článek v odborném periodiku
Name of source: Polymer
Publisher name: Elsevier Science
Place: Oxford
Page from-to: 166-175
Titles:
Language Name Abstract Keywords
cze Charakterizace komerčních hypervětvených alifatických polyesterů Stupeň rozvětvení alifatickcý hypervětvených polyesterů byl studován gelovou permeačních chromatografií kombinovamou s víceúhlovým rozptylem světla. Stupeň větverní je úměrný rozdílům mezi gyračním a hydrodynamickým poloměrem makromolekul.
eng Characterization of Commercial Aliphatic Hyperbranched Polyesters Commercially available Boltorn Hx (x=20, 30) hyperbranched (HB) polyesters of different theoretical core/monomer ratio (1/12 for H20 and 1/28 for H30) were characterized with respect to molar mass, composition, and structure. The results were compared to those obtained for the Boltorn H40 with a core/monomer ratio of 1/60 [Žagar E, Žigon M. Macromolecules 2002;35:9913 [11]]. The main side reaction in the pseudo one-pot synthesis of Boltorn polymers is a self-condensation of bis-MPA leading to the formation of HB structures without a core molecule. These are actually branches containing an unreacted carboxyl group. The fraction of HB structures without a core molecule increases with decreasing core/monomer ratio due to the decreasing fraction of HB structures with a core molecule. Since HB structures without a core molecule are of lower molar masses than HB structures with a core molecule, they particularly decrease the number average molar masses of the samples compared to the theoretically calculated ones. The polydispersity of Boltorn Hx increases with decreasing core/monomer ratio. Some of the hydroxyl groups were found to react intramoleculary forming ether bonds. Boltorn Hx polyesters have low degrees of branching due to the limited carboxyl group conversions, low DPn values, the presence of the core unit, and lower reactivity of hydroxyl groups in linear repeat units compared to those in terminal ones. The degree of branching according to Frey increases with decreasing core/monomer ratio. Polymers characterization; hyperbranched aliphatic polyesters

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