Linear-dendritic nonionic poly(propylene oxide)-polyglycerol surfactants |
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Authors: | Vladislav IstratovHolger Kautz Yong-Keun KimRolf Schubert Holger Frey |
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Institution: | a Department Organic and Macromolecular Chemistry, Institute of Organic Chemistry, Johannes-Gutenberg-University Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany b Institute for Pharmaceutical Technology, University of Freiburg, Hermann-Herder-Straße 9, D-79104 Freiburg, Germany |
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Abstract: | A new type of linear-hyperbranched surfactant has been prepared by anionic ring-opening multibranching polymerization of glycidol onto an end-functional poly(propylene oxide) (PPO) macroinitiator. A hyperbranched, highly hydrophilic polyglycerol block is obtained as the polar segment of the structure. Molecular weights of the nonionic amphiphiles obtained were in the range of 390 to 8,600 g/mol. For comparison, initiators bearing a C16 alkyl chain have also been employed. Furthermore, hyperbranched polyglycerol homopolymers were investigated with respect to amphiphilic properties. All linear-dendritic amphiphiles have been characterized by SEC, DSC, 13C and 1H NMR spectroscopy. A fluorescence-probe technique based on diphenyl hexatriene (DPH) as probe molecule was employed to determine the CMC (critical micelle concentration) of the samples in water. CMCs varied from 7.5×10−6 to 1.7×10−3 M and were found to depend on the copolymer architecture and the hydrophilic/hydrophobic balance. Measurements at pH 6.75 and 3.00 revealed an increase of the CMC by a factor of 10 for the amine containing copolymers upon lowering of the pH. |
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Keywords: | hyperbranched polymers dendritic block copolymers polyglycerol surfactants critical micelle concentration |
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