, where poly(ethylene oxide) is included in an amount ranging from at least about 50% by weight of the polymeric chain and] L is hydroxyl, a halide such as Cl, I or Br or an ester group which can be prepared from a hydroxyl group such as an alkyl, phenyl, benzyl or substituted alkyl, phenyl or benzyl group, include activated ester groups such as a tosyl group, mesyl group or related activated grou