Diblock Copolymer Melts in Electric Fields:  The Transition from Parallel to Perpendicular Alignment Using a Capacitor Analogy

Abstract

We consider alignment of a symmetric diblock copolymer melt thin film or bulk phase by an electric field using a capacitor analogy. For the lamellar phase we show that alignment of the lamellae in the direction perpendicular to the bounding electrodes, compared to parallel alignment, occurs for thicker films. For thin films the critical electric field required for a transition from parallel to perpendicular alignment is proportional to H -1/2 , where H is the film thickness. We also consider the possibility of a mixed lamellar morphology where, because the bounding electrodes prefer one block, parallel layers form adjacent to the electrodes, while in the interior region there is perpendicular alignment. We determine the conditions for such a morphology.

Block Copolymer at Nano-Patterned Surfaces

“…The orientation and alignment of lamellar and hexagonal phases of BCP were investigated, and, in particular, their transition between parallel ('lying down') and perpendicular ('standing up') orientations. Another useful method is the use of electric fields to orient anisotropic phases of BCP, such as lamellar and hexagonal, in a direction perpendicular to the solid surface [23][24][25][26][27][28][29][30][31].…”

Nanopatterns Produced by Directed Self-Assembly in Block Copolymer Thin Films

“…4.6). The electric field effect indeed competes with the surface effects, as was well documented theoretically [70,71], while also taking into account the effects of mobile charged impurities in the films [72]. The nanostructure development and alignment could be followed by time-resolved X-ray scattering in the cases of initially disordered and ordered films [69,73].…”

Influence of substrate interaction and confinement on electric-field-induced transition in symmetric block-copolymer thin films

“…While most of the earlier theoretical work in this regard focus on strong segregation limit (SSL), [22,24,26] literature on weak segregation limit (WSL) [24] is relatively sparse. A common finding in the SSL is the presence of three stable configurations, namely, parallel, perpendicular and mixed with respect to the substrate.…”

“…In contrast to stable parallel configuration in presence of substrate interaction, presence of electric field makes the perpendicular arrangement more stable. The reason for this can be rationalised in terms of dielectric permittivity mismatch between the two monomer components [21][22][23]. In electrostatics, the electric field isolines prefer to pass through the regions of higher permittivity [21,22].…”