Entropic penalty

In the case of t < Lo, it has been suggested that perpendicular lamellae are favored in the boundary-symmetric confined film because they avoid the entropic penalty associated with the compressed chain conformations in parallel-oriented microdomains [109]. In boundary-asymmetric substrate-supported films, various kinds of morphologies, including hybrid morphologies that combine surface-parallel and surface-perpendicular components, are predicted, as well as observed, depending on the film thickness difference and surface/interface energies [14,41,120]. 

In the case where the macromolecular backbone is flexible, the axial tension may affect the molecular conformation. Flexibility of the main chain can be realized by bond rotational isomerism and minimizes the entropic penalty caused by the stretching of the main chain. As depicted in Fig. 21 on the right ... 

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