Organized structures in diblock copolymer films of polystyrene and poly-para-methylstyrene

Dewetting of Thin Diblock Copolymer Films: Spinodal Dewetting Kinetics

“…Thus, on the time scale of the experiment this film remains stable. However, the stability of thicker P(S- b -pMS) films is in good agreement with previous experimental observations. ,− …”

“…In general, PpMS prefers to segregate at the film surface due to the large differences in the surface energies of both components PS and PpMS (γ(PpMS)/γ(PS) = 0.86). Whereas in thick films the lamellar order induced by this surface segregation decays toward the bulk, in thin films the ratio of film thickness l and lamellar spacing L becomes important. − In the model system P(S- b -pMS) the lamellar order is installed right after preparation as well as after annealing. , However, the initial periodicity L̃ = 240 ± 10 Å, which commonly installs right after preparation in the case of thick P(S- b -pMS) films, , is smaller than the bulk lamellar period L . In the case of 300 Å film thickness the surface tension force a surface segregation of PpMS, but the limited available volume of polymeric material ( l = 6 L̃ /5 = 2 L /3) prevents the buildup of a complete lamella.…”

“…In contrast to bulk samples, in thin films the interactions with both boundaries influence the morphology as well as its orientation. In the case of complete wetting of each interface by one component of the diblock copolymer, a lamellar order parallel to the interfaces is forced. − If one interface is free, like a film surface toward vacuum, the film thickness is quantized in units of the lamellar bulk period L . If the initial film thickness is not commensurate with this constraint, an incomplete top layer is formed .…”

Structure Formation in Two-Dimensionally Confined Diblock Copolymer Films

“…The lamellae in thin films are oriented parallel to the solid support. [35][36][37][38][39][40] With decreasing film thickness, the confinement gives rise to an interplay between the intrinsic length scale of the bulk structure and the geometry of the film. [41][42][43][44][45] Consequently, transitions between phases of identical symmetry but different orientation with respect to the confining walls become energetically possible, and lamellar domains reorient from a parallel to a perpendicular arrangement.…”

Morphologies and Thermal Variability of Patterned Polymer Films with Poly(styrene-co-maleic anhydride)

“…The heating above the glass transition temperature leads to destabilization of the film: in the early stages of dewetting holes are formed due to thermal fluctuations (spinodal dewetting) [27] or a nucleation and growth process starting at defects [28]; in the last stage of dewetting a regular (spinodal dewetting) or an irregular (nucleation and growth process) structure is formed. The thermal instabilities of polystyrene diblock copolymers are related to the microphase separation temperature: for a moderate annealing of surface-deposited films, an exponentially decaying lamellar order of alternating copolymer segments is observed with annealing time [29], while aggressive annealing of a free-standing polystyrene film leads to the formation of holes [30].…”