The Solvent Distribution Effect on the Self-Assembly of Symmetric Triblock Copolymers during Solvent Vapor Annealing

Abstract

Using a combination of systematic experiments and Monte Carlo simulations, this report demonstrates that the distribution of neutral solvent has a strong impact on the quality and kinetics of the self-assembly of block copolymers in thin films. Both methyl ethyl ketone (MEK, a good solvent) and acetone (a relatively poor solvent) were used for the solvent vapor annealing (SVA) of thin films of poly(2vinylpyridine)-block-polystyrene-block-poly(2-vinylpyridine) (VSV) triblock copolymer. Acetone, the poorer solvent, accumulated at the interface of the VSV domains, while MEK was distributed more uniformly throughout the VSV. As a result, acetone screened the interactions between the blocks of the copolymer more than MEK. Because MEK afforded less screening of the different blocks, solvent annealing with MEK led to self-assembly of lower molecular weight VSV triblock copolymers than was possible with acetone. Solvent annealing with MEK also led to slower self-assembly kinetics and smaller correlation lengths in the assembled pattern compared to solvent annealing with acetone. Finally, long-range ordered structures of low molecular weight VSV triblock copolymer on a chemical pattern via directed self-assembly was demonstrated with 6× density multiplication by annealing in MEK.

Inhibition of bacterial adhesion and biofilm formation by a textured fluorinated alkoxyphosphazene surface

“…The THF-film appeared to have non-uniform thickness and structure due to the fast evaporation, while MEK-film appeared uniform and clear. The other reason for good quality of MEK-film may be due to the more uniform distribution of MEK throughout the polymers, as was confirmed in a triblock copolymer [ 36 ]. Taken together we conclude that MEK is the best solvent for fabrication of textured polyphosphazene films among the four commonly used solvents tested.…”

Peptide-Modified Electrode Surfaces for Promoting Anion Exchange Ionomer Microphase Separation and Ionic Conductivity

“…The plasticized film becomes a polymer melt, and it can now diffuse and reorganize itself into a thermodynamically favorable microstructure. 37 The overall goal of this study is to characterize the effect of biomolecular surface modifications with and without solvent annealing on the microstructure configurations of AEIs and subsequent ionic conductivity. The model AEI in this report is a random copolymer brush of poly(2,6-dimethyl 1,4-phenylene oxide) featuring quaternary benzyl N,N-dimethyl-n-decyl ammonium hydroxide/carbonate/bicarbonate anions (PPO-QDMDA).…”

“…Solvent vapor annealing lowers the glass transition of the polymer film below room temperature through solvent plasticization. The plasticized film becomes a polymer melt, and it can now diffuse and reorganize itself into a thermodynamically favorable microstructure …”

Electrolysis on a Chip with Tunable Thin Film Nanostructured PGM Electrocatalysts Generated from Self‐Assembled Block Copolymer Templates

“…This increase in mass normalized surface area hailed from the selection of the 3L47 BCP template that gives periodic feature sizes of 22 nm that yields Pt nanowire diameters of 11 nm. It is worth noting that 8.5 nm wire diameters are possible with PS b PVP [ 45 ] if the degree of polymerization is reduced further. Taller nanostructures may also be achieved by starting with thicker self‐assembled BCP films.…”