  The extension elasticity of rod-coil mutliblock copolymers is analyzed for
two experimentally accessible situations. In the quenched case, when the
architecture is fixed by the synthesis, the force law is distinguished by a
sharp change in the slope. In the annealed case, where interconversion between
rod and coil states is possible, the resulting force law is sigmoid with a
pronounced plateau. This last case is realized, for example, when
homopolypeptides capable of undergoing a helix-coil transition are extended
from a coil state. Both scenarios are relevant to the analysis and design of
experiments involving single molecule mechanical measurements of biopolymers
and synthetic macromolecules.
