Synthesis of functionalised 12-,13- and 14-membered crown ethers bearing exocyclic polymerisable groups and the binding properties and conductivities of their lithium doped polymers

The synthesis of a series of [12], [13] and [14]-membered crown ethers bearing an exocyclic polymerisable methacrylate is reported. The spacing group between the ring and the methacrylate is either a simple alkyl chain, [CH₂] or [CH₂]₆, or an oxydiethylene chain. The relative binding ability of the 'mono and di-substituted' macrocyclic rings towards Li⁺ is compared by ¹³C NMR analysis. Radical polymerisation gives the amorphous polymers in which the glass transition temperature is primarily controlled by the nature of the spacer group. In the lithium doped polymers, for a given glass transition temperature, T_g, the [12]-ring materials show enhanced ionic conductivities over the [14]-ring analogues which may be related to the lower rate of lithium exchange (in the former series) or to an enhanced tendency of the [12]-ring systems to form 2:1 complexes with more effective counterion separation.