Dipyridyl(pyridazine)-decorated macroporous poly(dicyclopentadiene) (pDCPD) foams prepared by inverse electron demand Diels-Alder (iEDDA) chemistry
Astrid-Caroline Knall,* David Reishofer, Sebastijan Kovačič, Christian Slugovc
Institute for Chemistry and Technology of Materials
12:00 - 12:20 Thursday 24 October 2013 HS II, Alte Technik Curing of the difunctional monomer dicyclopentadiene (DCPD) via Ring-Opening Metathesis Polymerisation (ROMP) leads to poly-(dicyclopentadiene) (pDCPD), a thermoset material with favourable mechanical properties. By performing this polymerisation in a stabilised High Internal Phase Emulsion (HIPE), macroporous polymeric pDCPD foams are obtained which combine an interconnected microcellular open porous structure with favourable mechanical properties such as the highest mechanical resilience reported amongst HIPE templated materials.[1] Common prerequisites for applications of such foams (e.g. in tissue engineering, water purification or as separator membranes in lithium-ion batteries) are good mechanical properties and easy methods to post-functionalise the foams.
The high degree of unsaturation in pDCPD (as a consequence of the metathesis polymerisation) offers ways for functionalisation (e.g. epoxidation or bromination followed by conversion with nucleophiles or radical initiated thiol–ene chemistry). Accordingly, pDCPD foams ideally fulfil the prerequisites for the preparation of highly functionalised porous materials.
Recently, we could show that the inverse electron demand Diels–Alder (iEDDA) reaction of tetrazines and olefins[2] is a straightforward and versatile method for the post-functionalisation of pDCPD foams. More precisely, iEDDA reactions performed on the double bonds in open cellular macroporous poly(dicyclopentadiene) monoliths, using di(pyridyl)tetrazine as reagent, yielded a high degree of functionalisation (up to 2 mmol pyridazines per g or 8 mmol N per g) of grafted di(pyridyl)pyridazines in a single step.[3] Furthermore, the ability of the grafted pyridazine ligands to coordinate metal ions and the influence of post-functionalisation on the mechanical properties of the pDCPD foams were studied.
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[1] Kovačič, S.; Matsko, N. B.; Jeřabek, K.; Krajnc, P.; Slugovc, C. J. Mater. Chem. A 2013, 1, 487-490.
[2] Knall, A.-C.; Slugovc, C. Chem. Soc. Rev. 2013, 42, 5131-5142.
[3] Knall, A.-C.; Kovačič, S.; Hollauf, M.; Reishofer, D.; Saf, R.; Slugovc, C. Chem. Commun. 2013, 49, 7325-7327.
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