Templated Self-assembly of a PS-branch-PDMS Bottlebrush Copolymer


Cheng, L.-C.; Gadelrab, K.R.; Kawamoto, K.; Yager, K.G.; Johnson, J.A.; Alexander-Katz, A.; Ross, C.A. "Templated Self-assembly of a PS-branch-PDMS Bottlebrush Copolymer" Nano Letters 2018, 18 4360–4369.
doi: 10.1021/acs.nanolett.8b01389


We study the self-assembly of bottlebrush copolymers under solvent vapor annealing conditions.


The self-assembly of block copolymers (BCPs) with novel architectures offers tremendous opportunities in nanoscale patterning and fabrication. Here, the thin film morphology, annealing kinetics, and topographical templating of an unconventional Janus-type “PS-branch-PDMS” bottlebrush copolymer (BBCP) are described. In the Janus-type BBCP, each segment of the bottlebrush backbone connects two immiscible side chain blocks. Thin films of a Janus-type BBCP with Mn = 609 kg/mol exhibited 22 nm period cylindrical microdomains with long-range order under solvent vapor annealing, and the effects of as-cast film thickness, solvent vapor pressure, and composition of the binary mixture of solvent vapors are described. The dynamic self-assembly process was characterized using in situ grazing-incidence X-ray scattering. Templated self-assembly of the BBCP within lithographically patterned substrates was demonstrated, showing distinct pattern orientation and dimensions that differ from conventional BCPs. Self-consistent field theory is used to elucidate details of the templated self-assembly behavior within confinement.