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Smigovec Ljubic T.,Slovenian National Institute of Chemistry | Pahovnik D.,Slovenian National Institute of Chemistry | Zigon M.,Slovenian National Institute of Chemistry | Zigon M.,University College for Polymer Technology | Zagar E.,Slovenian National Institute of Chemistry
The Scientific World Journal | Year: 2012

The separation of a mixture of three poly(styrene-block-t-butyl methacrylate) copolymers (PS-b-PtBMA), consisting of polystyrene (PS) blocks of similar length and t-butyl methacrylate (PtBMA) blocks of different lengths, was performed using various chromatographic techniques, that is, a gradient liquid chromatography on reversed-phase (C18 and C8) and normal-phase columns, a liquid chromatography under critical conditions for polystyrene as well as a fully automated two-dimensional liquid chromatography that separates block copolymers by chemical composition in the first dimension and by molar mass in the second dimension. The results show that a partial separation of the mixture of PS-b-PtBMA copolymers can be achieved only by gradient liquid chromatography on reversed-phase columns. The coelution of the two block copolymers is ascribed to a much shorter PtBMA block length, compared to the PS block, as well as a small difference in the length of the PtBMA block in two of these copolymers, which was confirmed by SEC-MALS and NMR spectroscopy. © 2012 Tina Šmigovec Ljubič et al.


Zagar E.,Slovenian National Institute of Chemistry | Zigon M.,Slovenian National Institute of Chemistry | Zigon M.,University College for Polymer Technology
Progress in Polymer Science (Oxford) | Year: 2011

Due to their highly branched structure and the large number of functional groups hyperbranched polymers possess unique properties that make them interesting for uses in a wide variety of applications. Some of the most widely investigated hyperbranched polymers are the polyesters based on 2,2-bis(methylol)propionic acid. In this paper we present the results of characterization studies of hyperbranched polyesters based on 2,2-bis(methylol)propionic acid which show that they are very complex products with a multidimensional distribution of various properties. The influence of the synthesis conditions on the structure and molar-mass characteristics of hyperbranched polyesters as well as the findings that allow a thorough understanding of the structure-property relationships are reviewed in detail. © 2010 Elsevier Ltd All rights reserved.


Gricar M.,Slovenian National Institute of Chemistry | Zigon M.,Slovenian National Institute of Chemistry | Zigon M.,University College for Polymer Technology | Ljubic T.S.,Slovenian National Institute of Chemistry | And 2 more authors.
Chromatographia | Year: 2012

Water-soluble sodium poly(aspartate-co-lactide) (PALNa) copolymers with a molar ratio of aspartateto- lactide units equal to 1:0.6, 1:1.0 and 1:1.5 were studied using NMR spectroscopy to determine the composition as well as SEC-MALS and static light-scattering measurements to determine the molar-mass characteristics of the copolymers. In the copolymer aqueous solutions, highmolar- mass species were detected, most probably due to the incomplete dissolution of the samples. The molar-mass averages determined in water with added simple electrolyte, i.e., NaCl, were much lower than the values determined in pure water. The concentration of the salt, which allows dissolution on a molecular level, and the separation predominantly according to a size-exclusion mechanism depend on the chemical composition of the PALNa copolymers. The optimal mobile phase for the PALNa-1/ 0.6 and the PALNa-1/1.0 copolymers was 0.1 M NaCl at pH 9, and for the PALNa-1/1.5 copolymer with a higher content of lactide units it was 0.05 M NaCl at pH 9. The molar-mass averages of the PALNa-1/1.0 copolymer, determined by SEC-MALS and static light-scattering measurements, were comparable. © 2012 Springer-Verlag.

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