Zhen Jiang, Andrew Whittaker*, Idriss Blakey

 

The University of Queensland,
Australian Institute for Bioengineering and Nanotechnology
St Lucia, 4072, Australia

 

Block copolymers (BCP) can self-assemble to form different nanoscale morphologies with feature sizes on the order of several to hundreds of nanometers. The resulting self-assembled nanostructures are very promising for a wide range of applications in nanolithography, electronic devices, and metallic materials.1 Over the past few decades, there have been a large number of reports on precisely tuning the interfacial interactions between BCPs and the substrate interface. The preparation of perpendicularly orientated BCP nanodomains on the substrate surface is desirable for the transfer of nanopatterns into the underlying substrate2 Despite this work, it is still challenging to achieve precise spatial control of surface interactions across a single substrate, which is very important for many applications including chemoepitaxy, transistor design and field effect transistors.2

Recently, the use of light energy to direct orientation has recently attracted attention, as light can be localized in time and space and could assist in achieving spatial control of material properties.3,4 Herein, we report a facile strategy for spatial control of nanodomain orientation of block copolymers through utilizing a single-component photoactive polymer layer. After exposure to UV light, poly(4-acetoxystyrene) undergo the photo-Fries rearrangement and produce hydroxyketones in the illuminated areas. Asymmetric, neutral and symmetric wetting of the BCP films have been induced simply by tuning the dose and post-exposure treatment with carboxylic acid chlorides. Furthermore, such photo-Fries rearrangement processess could be combined with mask-based patterning techniques to fabricate a range of microscale patterns.

Figure 1. Left: (A) Photo-Fries rearrangement and post-exposure reaction. (B-D) AFM images of P(S-b-MMA) on exposed films at different doses. (E-G) Optical micrographs of P(S-b-MMA) on poly(4-acetoxystyrene) exposed to patterned irradiation. (H) AFM image of outlined area indicating perpendicular orientation.

References

  1. F. Schacher, P. A. Rupar, and I.Manners, Angew. Chem. Int. Ed. 2012, 51, 7898 – 7921.
  2. C. M. Bates, M. J. Maher, D. W. Janes, C, J. Ellison, and C. G. Willson, Macromolecules 2014, 47, 2−12
  3. A. P. Lane, M. J. Maher, C. G. Willson and C. J. Ellison, ACS Macro Lett. 2016, 5, 460−465.

Venue

Room: 
AEB Auditorium