Synthesis and thermal analysis of crosslinked imidazolium-containing polyester networks prepared by Michael addition polymerization

Several new covalently crosslinked imidazolium-containing polyester networks were prepared by Michael addition polymerization to probe how ionic functionality might affect thermal properties such as glass transition temperature (T-g) and thermal decomposition (T-d5%). A structure-activity relationship was investigated involving a variation of the methylene spacer and the counteranion of the acetoacetate precursors. Analysis of T-g by differential scanning calorimetry (DSC) indicated that a longer methylene spacer (n = 6 versus 2) resulted in lower T-g values due to increased chain mobility. It was also discovered that the larger the counteranion, the lower the T-g(Br- > NO3- approximate to BF4- CF3CO2- > NTf2-). Thermogravimetric analysis (TGA) indicated that the thermal stability of the polyesters was inversely related to the basicity of the counteranion used, following the trend: (NTf2- > BF4- > NO3- > Br-). The exception was the trifluoroacetate-containing polyester, which exhibited the lowest thermal stability. Published by Elsevier Ltd.