Orienting Thin Films of Lamellar Block Copolymer: The Combined Effect of Mobile Ions and Electric Field

Abstract

We study thin films of A/B diblock copolymer in a lamellar phase confined between two parallel plates (electrodes) that impose a constant voltage across the film. The weak-segregation limit is explored via a Ginzburg-Landau-like free-energy expansion. We focus on the relative stability of parallel and perpendicular orientations of the lamellar phase, and how they are affected by variation of the following four experimental controllable parameters: addition of free ions, the difference in ionic solubilities between the A and B blocks, their dielectric contrast, and the preferential interaction energy of the plates with the blocks. It is found that, in general, the addition of ions lowers the critical voltage needed to reorient the lamellae from being parallel to the plates, to being perpendicular to them. The largest reduction in critical voltage is obtained when the ions are preferentially solubilized in the block that is not preferred by the plates. This reduction is even further enhanced when the dielectric constant of this block has the higher value. These predictions are all subject to experimental test. arXiv:1807.06694v1 [cond-mat.soft]

Mechanistic Elucidation of Electronically Conductive PEDOT:PSS Tailored Binder for a Potassium‐Ion Battery Graphite Anode: Electrochemical, Mechanical, and Thermal Safety Aspects

“…It has been observed that lamellar grains for block copolymer electrolytes can orient themselves under polarization with an electric field, reducing the tortuosity of the conducting medium. [ 64–67 ] Similarly, PEDOT:PSS may orient under the electric field experienced during current polarization. Second, PEDOT:PSS is brittle.…”

Morphology Control of Perpendicularly Oriented Lamellar Films from Azobenzene-Containing Block Copolymers with Different Spacer Lengths

“…Nowadays, the orientation control of lamella-forming BCP films has also become one of the key scientific problems in the development and applications of template materials. Generally, the orientation of lamellar BCP films depends on the total free energy, including interfacial energy of two phases, conformational entropy of polymer chains, free energy from the top surface or the substrate. , Many approaches have been developed for balancing the domain surface energies to achieve the orientation control of BCP films by pre- or postprocesses, such as a random copolymer brush attached to the substrate, laser, graphoepitaxy, electric field, magnetic field, top-coating, etc . In our previous work, we incorporated the azobenzene (Azo) liquid crystalline (LC) mesogens into the side chains of polymethacrylate (PMMA) to construct different azobenzene-containing BCPs, such as poly­(ethylene oxide)- block -poly­{11-[4-(4-butylphenylazo)­phenoxy]-undecyl methacrylate} (PEO- b -PMA­(11 C )­Az), poly­(4-vinylpyridine)- block -PMA­(11 C )­Az (P4VP- b -PMA­(11 C )­Az), and polystyrene- block -PMA­(11 C )­Az (PS- b -PMA­(11 C )­Az) .…”

Effect of In‐Plane Electric Field on the Microphase Separation in Thin Films of a Symmetric ABA Triblock Copolymer

“…[13][14][15][16][17] The field effect can be rationalized in terms of a simple capacitor analogy [18][19][20] and is nowadays considered as a promising tool for the directed selfassembly of block copolymers. [4][5][6][7]21] Various theoretical approaches including Ginzburg-Landautype theory, [20,[22][23][24][25][26][27] strong-segregation theory, [18][19][20]28] selfconsistent field theory (SCFT), [29][30][31][32][33][34] dynamic theories, [35][36][37][38][39] and molecular simulations [40][41][42][43] allowed one to analyze the block copolymer behavior under electric fields in bulk and spatially-restricted model systems (films, etc). It appeared that the conformations of individual nonionic macromolecules [23] and the order-disorder transition [22,44] were not much affected by practically available electric fields.…”

“…Various theoretical approaches including Ginzburg–Landau‐type theory, [ 20,22–27 ] strong‐segregation theory, [ 18–20,28 ] self‐consistent field theory (SCFT), [ 29–34 ] dynamic theories, [ 35–39 ] and molecular simulations [ 40–43 ] allowed one to analyze the block copolymer behavior under electric fields in bulk and spatially‐restricted model systems (films, etc). It appeared that the conformations of individual nonionic macromolecules [ 23 ] and the order‐disorder transition [ 22,44 ] were not much affected by practically available electric fields.…”