Models of polymers subject to a force*

Atomic force microscopy (AFM) and optical tweezer techniques allow individual polymer molecules to be micromanipulated. For instance, an adsorbed polymer can be pulled off a surface. We consider simple, exactly solvable models of this effect. In addition, we consider models of random copolymers adsorbed at an impenetrable surface and localized at an interface and investigate their response to an elongational force. This is related to a model of unzipping duplex DNA.