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Ahmed H.,Central Polymer Laboratories CePoL | Ahmed H.,University of Graz | Trathnigg B.,Central Polymer Laboratories CePoL | Trathnigg B.,University of Graz | And 4 more authors.
European Polymer Journal | Year: 2010

Polymers of ε-caprolactone were synthesized by microwave-assisted polymerization initiated with polyethylene glycols (PEG 200 and PEG 300) and monodisperse diols (mono-, di-, tri-, tetra- and hexaethylene glycol) and tin octoate as catalyst. These polymers were characterized by different chromatographic techniques (SEC, LAC and LCCC) and MALDI-TOF-MS. A comparison with commercially available polycaprolactone diols with molecular weight 530 and 830 showed that the new polymers had a much higher content of triblock structures, while the commercial samples contained considerable amounts of diblocks. © 2009 Elsevier Ltd. All rights reserved. Source

Malik M.I.,University of Karachi | Malik M.I.,Central Polymer Laboratories CePoL | Malik M.I.,University of Graz | Ahmed H.,Central Polymer Laboratories CePoL | And 3 more authors.
Journal of Chromatography A | Year: 2013

Telechelic oligomers based on diethylene glycol or lower polyethylene glycols and caprolactone or butene oxide can be separated according to their architecture by means of liquid chromatography under adsorption conditions for the hydrophobic block and critical or exclusion conditions for PEG. This behavior, which is predicted by the theory, can be verified by the experiment for block copolymers of ethylene oxide with e{open}-caprolactone and butene oxide. The individual peaks were identified by matrix-assisted time-of-flight mass spectrometry (MALDI-TOF-MS) of fractions obtained by semipreparative liquid chromatography at critical conditions of center block (PEG) and adsorption conditions for outer blocks (PCL and PBO). © 2013 Elsevier B.V. Source

Malik M.I.,University of Graz | Malik M.I.,Central Polymer Laboratories CePoL | Trathnigg B.,University of Graz | Trathnigg B.,Central Polymer Laboratories CePoL | And 4 more authors.
Analytica Chimica Acta | Year: 2010

Polyoxyalkylene diblock copolymers (consisting of PEO as hydrophilic block and PBO or PHO as hydrophobic block) are characterized by combination of two dimensional liquid chromatography and MALDI-TOF-MS. Liquid chromatography under critical conditions (LCCC) is used as first dimension and fractions are collected, mobile phase evaporated and diluted in the mobile phase used in the second dimension (SEC, LCCC or LAC). This two-dimensional chromatography in combination of MALDI-TOF-MS gives information about purity of reaction products, presence of the byproducts, chemical composition and molar mass distribution of all the products. © 2009 Elsevier B.V. All rights reserved. Source

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