Phase Diagrams of Surface Structures in Swollen Films

2 Phase Diagrams of Surface Structures in Swollen Films 

As established by Knoll et al. [49, 62], exposing thin films to well-controlled vapor pressure with a subsequent fast quench provides reproducible phase behavior under variation of the film thickness and of the polymer volume fraction (Fig. 15). At favored film thicknesses, cylinders orient parallel to the film plane, whereas a perpendicular orientation dominates at intermediate film thicknesses. In films thinner than 1.5 nm domain spacings and at high polymer concentration, the cylindrical 

3 Confinement Effects on the Microphase Separation and Polymer-Solvent Interactions in Swollen Films 

The current trend towards miniaturization of functional systems and devices has driven the study of confinement effects (finite film thickness and the nature of the binding interfaces) on the fundamental physical properties of soft materials. Rapid developments of novel sensor and lab-on-chip technologies, and of polymer-based stimuli-responsive materials, raise the question of changes in solvent-polymer interactions under confinement. 

In contrast to swollen homopolymer films, only a limited number of studies on thin films of block copolymers have been reported in which the degree of the film swelling has been directly accessed. In situ SE has been used to evaluate the polymer-solvent interaction parameters [144], to construct phase diagrams of surface structures [49, 51], and to control the mechanism of lamella reorientation in thick swollen films [118, 163, 164], Spectroscopic reflectometry combined with real-time GISAXS has been used to follow structural instabilities in swollen lamella films [165], Recently, it was demonstrated that swelling of diblock copolymer films in organic selective and non-selective solvents follows the same physical behavior as in thin films of homopolymers [119]. 

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