10.1021/acs.macromol.7b00876.s001
Cameron
K. Shelton
Cameron
K.
Shelton
Ronald L. Jones
Ronald L.
Jones
Thomas H. Epps
Thomas H.
Epps
Kinetics of Domain Alignment in Block Polymer Thin
Films during Solvent Vapor Annealing with Soft Shear: An <i>in
Situ</i> Small-Angle Neutron Scattering Investigation
American Chemical Society
2017
alignment
deswelling
gradient thickness PDMS pads
BP nanostructure responses
shear forces
SVA-SS parameters
styrene
SI
Solvent Vapor Annealing
film
SANS
Situ Small-Angle Neutron Scattering Investigation
2017-07-10 18:06:17
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Kinetics_of_Domain_Alignment_in_Block_Polymer_Thin_Films_during_Solvent_Vapor_Annealing_with_Soft_Shear_An_i_in_Situ_i_Small-Angle_Neutron_Scattering_Investigation/5191747
We
employed small-angle neutron scattering (SANS) to identify the
kinetic pathways between disordered and ordered states in block polymer
(BP) thin films subjected to solvent vapor annealing with soft shear
(SVA-SS), which enabled the optimization of large-scale nanostructure
ordering and alignment. The judicious incorporation of deuteration
in poly(deuterated styrene-<i>b</i>-isoprene-<i>b</i>-deuterated styrene) (<i>d</i>SI<i>d</i>S) films
(≈200 nm thick) provided sufficient contrast in the SANS experiments
to overcome the diffuse scattering contribution from thicker (nondeuterated)
polydimethylsiloxane (PDMS) pads (≈500 μm thick)
and permit the <i>in situ</i> tracking of BP nanostructure
responses to swelling, deswelling, and shear forces. We determined
that as the <i>d</i>SI<i>d</i>S and PDMS swelled
during SVA-SS, the lateral expansion of the PDMS across the pinned
film induced a shear force that promoted chain mixing and nanostructure
disordering in our solvent swollen systems. As solvent was removed
from the films (deswelling), smaller grains began to form that had
lower energetic barriers to alignment in the direction of the drying
front(s), which facilitated nanostructure alignment. Changing SVA-SS
parameters such as swelling ratio, PDMS elasticity, and deswell rate
altered the ordering kinetics and affected domain directionality over
a length scale that was readily captured through SANS studies. By
exploiting SVA-SS parameters that create large and controllable shear
forces, we also developed a robust and “hands-off” approach
to direct BP thin film self-assembly using gradient thickness PDMS
pads in SVA-SS. This proposed technique can be applied to quickly
and reliably generate cost-effective microscopic patterns over macroscopic
areas for both nanotechnology research and industrial applications.