Coupling Between Curvature and Pattern Configurations in Block Copolymer Free-Standing Membranes and Thin Films

DA VEGA; ABATE A; CATALINI, G.; PEZZUTTI A; GOMEZ LR; REGISTER RA; GIANG THI VU; SCHMID, F

Mainz

Workshop; Centre Européen de Calcul Atomique et Moléculaire (CECAM).; 2017

Centre Européen de Calcul Atomique et Moléculaire (CECAM). Mainz Materials Simulation Days 2017

Both, experiments and theory on curved block copolymer thin films and free-standing membranes have shown that the mechanisms of phase transition, kinetics of ordering, structure of defects and equilibrium pattern configurations are deeply affected by the intrinsic and extrinsic geometry in which the system is embedded [1,3]. Here we employed a Brazovskii free energy model and self-consistent field theory (SCFT) calculations to analyze the coupling between the smectic textures developed by cylinder forming block copolymer systems and the mean curvature of the film. For weak curvatures, it was found that the free energy of the block copolymer film follows a Helfrich form, with a bending constant that depends on the pattern orientation with regard to the directions of main curvature. The strong anisotropy in the bending constant explains the main geometrical features of the out-of-plane deformations observed in free-standing block copolymer membranes, where disclinations act as sources of Gaussian curvature [4]. These results are in very good agreement with experimental data of poly(styrene)-co-poly( ethylene-alt-propylene) membranes and thin films deposited onto curved substrates. References[1] D. A. Vega, L. R. Gómez, A. D. Pezzutti, F. Pardo, P. M. Chaikin and R. A. Register, Soft Matter 9 9385 (2013).[2] A. D. Pezzutti, L. R. Gómez, and D. A. Vega, Soft Matter 11 2866 (2015).[3] L. R. Gómez, N. A. García, V. Vitelli, J. Lorenzana, and D. A. Vega. Nature Communications 6 6856 (2015).[4] E. A. Matsumoto, D.A. Vega, A. D. Pezzutti, N. A. García, P. M. Chaikin, and R. A. Register, PNAS 112 12639 (2015).