Extension of rod-coil multiblock copolymers and the effect of the helix-coil transition

The extension elasticity of rod-coil mutliblock copolymers is analyzed for two experimentally accessible situations. In the quenched case, when the ar chitecture is fixed by the synthesis, the force law is distinguished by a s harp change in the slope. In the annealed case, where interconversion betwe en rod and coil states is possible, the resulting force law is sigmoid with a pronounced plateau. This last case is realized, for example, when homopo lypeptides capable of undergoing a helix-coil transition are extended from a coil state.