Supporting ruthenium initiator on PolyHIPE

PolyHIPE samples were successfully synthesised using divinylbenzene and styrene as polymerisable continuous phase, aqueous phase containing potassium persulphate and calcium chloride dihydrate, a mixture of emulsifiers (SPAN20, CTAB and DDBSS) and toluene as a porogen. The PolyHIPE samples 1 and 2 and the PolyHIPE sample 3 were designed to be 90 and 92% porous, respectively, based on the aqueous phase content. PolyHIPE samples were found to be porous and open-cell microstructures with the surface area of 370–430 m2 g−1.Alkylidene exchange reactions were carried out between the double bonds of the PolyHIPE and the ruthenium initiator, Ru(CHPh)(PCy3)2Cl2, for the attachment of the initiator. The amount of initiator loading was determined by phosphorous analysis and for the first time by Rutherford backscattering (RBS) analysis. The loading of the initiator on the PolyHIPE samples, based on phosphorous analysis, was found to be 0.09–0.19 mmol/g. The RBS analysis showed the level of initiator loading to be 0.053–0.097 mmol/g. The level of initiator loading obtained from the phosphorous and the RBS analysis is higher than 0.035 mmol/g reported previously for ruthenium initiator supported on crosslinked polystyrene. However, the level of initiator loading obtained from RBS analysis is lower than that obtained from the phosphorous analysis by ICP-OES. The reason for this discrepancy is believed to be due to inaccuracy of phosphorous analysis as the result of the insolubility of the PolyHIPE supported initiator.

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