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Three-Dimensional Self-Assembly of Rodcoil Copolymer Nanostructures

L. H. Radzilowski^†

Materials Research Laboratory, Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana

Champaign, Urbana, Illinois 61801

B. O. Carragher

Department of Cell and Structural Biology, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana

Champaign, Urbana, Illinois 61801

S. I. Stupp*

Materials Research Laboratory, Departments of Materials Science and Engineering and Chemistry, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana

Champaign, Urbana, Illinois 61801

Macromolecules, 1997, 30 (7), pp 2110–2119

DOI: 10.1021/ma9609700

Publication Date (Web): April 7, 1997

†

Current address: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

Abstract

We have used electron tomography to characterize the self-assembly of nanostructures formed by rodcoil copolymers. The rodcoil copolymers used contained a perfectly monodisperse rod segment prepared by stepwise synthesis. The chemical compound rod segment is, in turn, covalently linked at one terminus to an end-functionalized polyisoprene segment prepared by living polymerization. We found that rodcoil molecules with rod volume fraction equal to 0.36 self-assemble into long strips with a nanoscale cross section. At lower rod volume fractions, the rodcoil molecules self-assemble into supramolecular aggregates with nanoscale x,y,z dimensions. Interestingly, the nanostructures organize into discrete layers of uniform thickness, containing in some cases a hexagonal 2D superlattice of rodcoil aggregates. Furthermore, nanostructures were found to self-assemble in all cases with three-dimensional order across the layers. The unique three-dimensional order observed in multilayers of the nanostructures must originate in the anisotropic aggregation of rod segments and the consequent space filling requirements as well as coil entropic penalties.

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