Inexpensive BCP fabrication
Image credit: Peter Allen.
Researchers from the Institute for Molecular Engineering (IME) present a high-throughput and inexpensive fabrication approach that uses self-assembled block copolymer (BCP) films as templates to generate dense nanoscale chemical patterns of polymer brushes for the selective immobilization of Au nanoparticles (NPs). The research has been published in ACS Macro Letters.
The self-assembling nature of block copolymer (BCP) films has garnered a great deal of scientific interest due to potential applications in a variety of fields that have use for patterned nanoscale features. BCPs can be blended with a homopolymer as well as with other BCPs to tailor properties such as the domain spacing, mobility, and morphology of the uniform microdomain structure.
We present a high-throughput and inexpensive fabrication approach that uses self-assembled block copolymer (BCP) films as templates to generate dense nanoscale chemical patterns of polymer brushes for the selective immobilization of Au nanoparticles (NPs). A cross-linked random copolymer mat that contains styrene and methyl methacrylate units serves both as a base layer for perpendicular assembly of nanoscale domains of poly(styrene-block-methyl methacrylate) (PS-b-PMMA) films and as a nonadsorbing background layer that surrounds the chemical patterns.
The selective removal of the PMMA block and the underlying mat via oxygen plasma etching generates binding sites which are then functionalized with poly(2-vinylpyridine) (P2VP) brushes. Au NPs with a diameter of 13 nm selectively immobilize on the patterned P2VP brushes. An essential aspect in fabricating high quality chemical patterns is the superior behavior of methyl methacrylate containing cross-linked mats in retaining their chemistry during the grafting of P2VP brushes. The use of BCPs with different molecular weights and volume fractions allows for preparation of chemical patterns with different geometries, sizes, and pitches for generating arrays of single particles that hold great promise for applications that range from molecular sensing to optical devices.
M. Serdar Onses, Lei Wan, Xiaoying Liu, N. Burak Kiremitler, Hatice Yılmaz and Paul F. Nealey, “Self-Assembled Nanoparticle Arrays on Chemical Nanopatterns Prepared Using Block Copolymer Lithography,” ACS Macro Letters, 2015, 4 (12), pp. 1356–1361, DOI: 10.1021/acsmacrolett.5b00644, Published Online November 20, 2015.