Nanotemplates for Directed Assembly of Polymer Blends into Non-uniform Patterns

| June 4, 2013

This research was carried out by the CHN Program at the University of Massachusetts, Lowell.

Objective: This work focuses on developing a method for fabrication of highly ordered polymeric structures by direct assembly of polymer blends on chemically patterned surfaces.

A set of generated non-uniform geometries by direct assembly of PS/PAA blends: a) 90˚ bends, b) T-junctions, c) square arrays, d) circle arrays. Dark areas are PAA and the light areas PS.

A set of generated non-uniform geometries by direct assembly of PS/PAA blends:
a) 90˚ bends, b) T-junctions, c) square arrays, d) circle arrays. Dark areas are PAA and the light areas PS.

Broader Impact: The directed assembly of polymer blends offers an advantage over block copolymers in that a wide array of polymers and molecular weights are readily available for use. For many practical applications, including nanolithography, the formation of features with complex and non-regular geometries is important, for example, square arrays, circle arrays, T-junctions, and 90˚ bends, which is easily accomplished using polymer blends. The direct assembly of polymer blends to achieve highly ordered uniform and non-uniform structures in short times provides a high rate, high volume approach to nanomanufacturing these structures. Alternatively, these patterned polymers can be used as flexible templates for the assembly of other nanodevices, etc., that are appropriately modified to “mate” with the patterned polymers.

Significant Results: Chemically functionalized templates were prepared by patterning alkanethiols with different chemical functionality by combining electron beam lithography and self-assembly of alkanethiol molecules and then, using these chemically patterned templates to direct the assembly of polystyrene (PS)/polyacrylic acid (PAA) blends. We also studied the effect of specific chemical interactions on the ability to form these patterns in a rapid fashion. Understanding this interaction provides the ability to control the site-specific deposition of polymer blends in very short times. The benefit of this approach is that the selective assembly process can be finished in 30 seconds and does not require the long annealing times (3-7 days) often required in the conventional assembly of block copolymers. We have demonstrated this method can be used to generate a variety of complex geometries including 90o bends, T-junctions, square and circle arrays, which have potential applications in fabrication of integrated circuits in nanoelectronics.

NSF Grant Number: EEC-0425826
PI(s): J. Mead, C. Barry, A. Busnaina
Student and Post-doctoral Researchers: M. Wei, L. Fang, J. Lee, S. Somu, X. Xiong
Institutions: University of Massachusetts Lowell, Northeastern University