Influence of Temperature and Type of Solvents on the Microdomain Orientation ofPS‐b‐P2VPUltrathin Films by Solvent Annealing

Abstract

Summary The effect of temperature and type of solvent on the microdomain orientation during solvent‐annealing of block copolymer ultrathin films on silicon substrates was investigated using asymmetric polystyrene‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP) diblock copolymer. When the solvent‐annealing was performed with THF at 20°C, the ultrathin film exhibited a mixed orientation of cylinders parallel and perpendicular to the substrate while at 25°C only parallel cylinders were observed by AFM. The solvent annealing with acetone gave a dot pattern at 20°C and a line pattern at 25°C. On the other hand, in the case of solvent‐annealing with toluene perpendicular cylinders were observed at 25°C while at 20°C the morphology was not clear. The orientation and morphology of microdomains as well as the kinetics in PS‐b‐P2VP ultrathin films on solvent‐annealing is significantly affected by temperature and type of solvent. By controlling temperature and selecting the solvent, perpendicular cylinders can be formed predominantly on the substrates.

Perpendicular Structure Formation of Block Copolymer Thin Films during Thermal Solvent Vapor Annealing: Solvent and Thickness Effects

“…Generally, preferentially wetting of one block at the substrate surface or free surface on the contrary induces preferential parallel orientation of domains [ 22 ]. For example, Hasegawa et al showed that the use of nonselective tetrahydrofuran (THF), selective solvent acetone for P2VP domain, or selective solvent toluene for the PS domain in the annealing of thin films PS- b -P2VP could cause the BCP to form significantly different morphologies, further asserting that various perpendicular structures can be formed predominantly on the substrates with the proper choice of solvent [ 23 , 24 ]. In addition to the interfacial interaction greatly influenced by the solvent vapor in SVA systems, the thickness of BCP films also affects the orientation of domains [ 20 , 21 , 22 , 25 ].…”

Bioinspired Dynamically Switchable PANI/PS‐b‐P2VP Thin Films for Multicolored Electrochromic Displays with Long‐Term Durability

“…The sufficient mobility and the solvated lamellar micro‐domains lead to self‐assembly from disordered lamellar micro‐domains to long‐range ordered lamellar structure. [ 29,35–37 ]…”

“…The sufficient mobility and the solvated lamellar micro-domains lead to self-assembly from disordered lamellar micro-domains to long-range ordered lamellar structure. [29,[35][36][37] The gorgeous skin colors of cephalopods, comprised of pigment colors and structural colors, provide a new approach to tackle the limited color control in electrochromic materials. Here we show for the first time that color changes throughout a wide visible region can be realized, by a combination of the electrochromic thin film [38] and the structurally colored thin film under a small electrical bias.…”

Directed Self-assembly of Topcoat-free, Integration-friendly High-^|^chi; Block Copolymers

“…Many orientation control strategies for generating perpendicularly oriented BCP domains have been implemented with high- BCPs. For example, solvent vapor annealing has been used for orientation control of PS-b-PEO [3], PS-b-PDMS [4], PS-b-P2VP [5], PLA-b-PTMSS [6] and PMS-b-PHOST [7]. Introducing a solvent vapor chamber and kinetics of solvent vapor annealing may complicate DSA processing.…”