The polymerization of N-carboxyanhydride (NCA) at low temperatures is controlled and allows the synthesis of a variety of well-defined polypetides.
Hydrophobic deep eutectic solvents were used for the first time for the removal of metal ions from non-buffered water. It was shown that the extraction occurs via an ion exchange mechanism in which all transition metal ions could be extracted with high distribution coefficients, even for high Co concentrations and low DES/water mass ratios. Maximum extraction efficiency could be reached within 5 s and regeneration was possible.
(2015). Enzymatic synthesis and preliminary evaluation as coating of sorbitol-based, hydroxy-functional polyesters with controlled molecular weights. European Polymer Journal, 67, 459-475. DOI: 10.1016/j.eurpolymj.2014 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. By using a combination of bio-based monomers (sorbitol, 1,10-decanediol and a range of dicarboxylic acids), a series of novel sorbitol-based polyesters was prepared by solvent-free enzymatic polycondensation using an immobilized form of Candida antarctica lipase B (Novozyme 435). The aim was to prepare linear polyesters with pendant, curable hydroxyl groups along the polymer backbone. To achieve this, the polyester molecular weight was controlled by tuning the reaction time, enzyme loading and reaction stoichiometry. Extensive molecular and thermal characterization was performed, showing that the obtained polyesters were semi-crystalline materials with a low T g . The presence of sorbitol in the polyesters was confirmed through a qualitative investigation using MALDI-ToF-MS. The quantification of the sorbitol content in the polymers was achieved by inverse-gated decoupling 13 C NMR spectroscopy, while 31 P NMR provided information regarding the selectivity of CALB for the primary vs. the secondary hydroxyl groups. Moreover, 31 P NMR and potentiometric titration were utilized for the quantitative determination of the amount of carboxylic groups and hydroxyl functional groups present in the polyesters. The obtained hydroxyl-functional polyesters had suitable properties to be applied as solvent-borne coatings in terms of their molecular weight, functionality and thermal characteristics. Cross-linked coatings were prepared using different conventional curing agents, including two renewable diisocyanates (ethyl ester L-lysine diisocyanate and dimer fatty acid-based diisocyanate). The resulting poly(ester urethane) coatings were tested in terms of solvent resistance, hardness and resistance against rapid deformation, showing the beneficial effect of the implemented sorbitol on network formation.
DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
New bis(phenolate)amine-supported neodymium borohydride complexes and their previously reported samarium analogues were tested as catalysts for the polymerisation of styrene and isoprene. Reaction of Na2O2N(L) (L = py, OMe, NMe2) with Nd(BH4)3(THF)3 afforded the borohydride complexes Nd(O2N(L))(BH4)(THF) (L = py (1-Nd), OMe (2-Nd), NMe2 (3-Nd)). Complex 1-Nd has shown a propensity to form phenolate-O-bridged dimer [Nd(μ-O2N(py))(BH4)]2 (1′-Nd) as previously observed with the samarium analogues Sm(O2N(L))(BH4)(THF) (L = py or Pr). X-ray structures of 1′-Nd and 2-Nd were determined and are presented. The neodymium borohydride complexes 1-Nd to 3-Nd and their samarium analogues Sm(O2N(L))(BH4)(THF)x (L = py (1-Sm), OMe (2-Sm), NMe2 (3-Sm), Pr (4-Sm)) were tested as catalysts for the polymerisation of isoprene and styrene in the presence of n-butylethylmagnesium (Mg((n)Bu)(Et)). All complexes were found to be active for the polymerisation of isoprene in these conditions, leading to polyisoprene up to 95.1% trans-1,4 stereoregular. They were also found to be active for the polymerisation of styrene leading to atactic polystyrene in all cases. Interestingly, samarium-based complexes were found to be more active than the neodymium ones toward this latter monomer, in sharp contrast to what is usually observed with rare earth borohydride complexes. The structure of both trans-polyisoprenes and polystyrenes obtained were studied in detail by MALDI-ToF analysis in order to better understand the polymerisation mechanisms. The coordinative chain transfer polymerisation (CCTP) of both monomers was further conducted using Mg((n)Bu)(Et) as transfer agent. Finally, the statistical copolymerisation of isoprene and styrene was examined using these catalytic systems, leading to the formation of poly[(trans-1,4-isoprene)-co-styrene] with up to 39% of styrene moieties inserted in a highly trans-1,4-stereoregular polyisoprene.
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