Probing the Effect of Molecular Nonuniformity in Directed Self-Assembly of Diblock Copolymers in Nanoconfined Space.
Various complex self-assembled morphologies of lamellar- and cylinder-forming block copolymers comprising poly(dimethylsiloxane)-b-polylactide (PDMS-b-PLA) confined in cylindrical channels were generated. Combining top-down lithography with bottom-up block copolymer self-assembly grants access to morphologies that are otherwise inaccessible with the bulk materials. Channel diameter (D) was systematically varied with four diblock copolymers having different compositions and bulk domain spacing (L0), corresponding to a range of frustration ratios (D/L0 from 2 to 4). Excessive packing frustration imposed by the channels leads to contorted domains. The resulting morphologies depend strongly on both D/L0 and copolymer composition. Under several circumstances, mixtures of complex morphologies were observed, which hypothetically arise from the severe sensitivity to D/L0 combined with the inherent compositional/molar mass dispersities associated with the nonuniform synthetic materials and silicon templates. Stochastic calculations offer compelling support for the hypothesis, and tractable pathways toward solving this apparent conundrum are proposed. The materials hold great promise for next-generation nanofabrication to address several emerging technologies, offering significantly enhanced versatility to basic diblock copolymers as templates for fabricating complex nanoscale objects.
Institute for Complex Molecular Systems and Laboratory for Macromolecular and Organic Chemistry, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Louis M
LM
Pitet
Philips Group Innovation, Research , High Tech Campus 7, 5656 AE Eindhoven, The Netherlands.
Els
E
Alexander-Moonen
Philips Group Innovation, Research , High Tech Campus 7, 5656 AE Eindhoven, The Netherlands.
Emiel
E
Peeters
ASML , De Run 6501, Veldhoven, The Netherlands.
Tamara S
TS
Druzhinina
ASML , De Run 6501, Veldhoven, The Netherlands.
Sander F
SF
Wuister
McKetta Department of Chemical Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
Nathaniel A
NA
Lynd
Institute for Complex Molecular Systems and Laboratory for Macromolecular and Organic Chemistry, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
E W
EW
Meijer
block copolymer; bottom-up lithography; confined self-assembly; molecular nonuniformity; nanolithography