ION-PAIR AFFINITIES OF LINEAR POLYETHERS IMMOBILIZED ON POLY(STYRENE-CO-M-TMI) NETWORKS

Networks (RTMI) were synthesized by radical suspension polymerization of m-isopropenyl-alpha,alpha-dimethylbenzyl isocyanate (m-TMI), styren e, and divinylbenzene. They were then reacted with methoxypoly(ethylen e glycol)s of molecular weights varying from 208 to 1900. The relative affinity of the immobilized polyethers for alkali metal ions in tolue ne was determined spectrophotometrically with alkali metal picrates (P i-M+) by means of the competition equilibrium Pi-M+N + L reversible Pi -M+L + N, where N is the RTMI-bound polyether and L is a ligand used t o solubilize the picrate salt in toluene. For the same ligand L, the e quilibrium constant K for a series of RTMI networks with different lig ands N provides a measure of the relative binding constants of alkali metal picrates for the immobilized polyethers. The reliability of the competition method was checked, and the data were compared with the af finity of soluble polyethers for alkali metal picrates in toluene obta ined by the same competition method but with different networks.