Two-dimensional polymers with random short-range interactions

We use complete enumeration and Monte Carlo techniques to study two-dimensional self-avoiding pol!mer chains with quenched ''charges'' +/-1. The interaction of charges at neighboring lattice sites is described by q(i)q(j). We find that a polymer undergoes a collapse transition at a temperature T-theta, which decreases with increasing imbalance between charges. At the transition point, the dependence of the radius of gyration of the polymer on the number of monomers is characterized by an exponent v(theta) = 0.60 +/- 0.02, which is slightly larger than the similar exponent for homopolymers. We find no evidence of freezing at low temperatures.