Alternative to dielectric for polarization in Poisson equation.

 I would like to use the Poisson Boltzmann equation to model
 polymerization.  This approach requires the use of a dielectric value for
 the monomers.  When the monomers are far apart, this may produce
 reasonable results.  However, as the monomers approach each other, a
 constant scalar dielectric model will break down.  Does anybody know of
 any papers that correct for polarization using some other approach?