EQUILIBRIUM PROPERTIES OF POLYAMPHOLYTES IN ELECTRIC-FIELDS

An analytically tractable model for the description of a charged polym er chain (polyampholyte) in an external electric field is presented. T he chain is comprised of mass points and their connectivity is taken i nto account by harmonic constraints. In particular the finite extensib ility of a chain is captured by our approach. Equilibrium properties f or chains of various charge distributions are calculated, especially f or intermediate and strong electric fields. Particularly, chains of al ternating positive and negative charges are considered within a discre te chain model. For intermediate electric fields such chains exhibit s tretched configurations, whereas for strong electric fields a collapse or stretching occurs depending on the number of mass points. In addit ion a continuous chain with random charge density is considered. Our i nvestigations demonstrate that the equilibrium properties of polyampho lytes in strong electric fields decisively depend on the charge distri bution along the chain. (C) 1997 American Institute of Physics.