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Architecture-Induced Phase Immiscibility in a Diblock/ Multiblock Copolymer Blend

Summary: Architecture-Induced Phase Immiscibility in a Diblock/
Multiblock Copolymer Blend
Richard J. Spontak,*, Jennifer C. Fung, Michael B. Braunfeld,
John W. Sedat, David A. Agard, Arman Ashraf,| and Steven D. Smith*,|
Department of Materials Science & Engineering, North Carolina State University,
Raleigh, North Carolina 27695, Graduate Group in Biophysics and Department of
Biophysics & Biochemistry and Howard Hughes Medical Institute, University of
California, San Francisco, California 94143, and Corporate Research Division,
The Procter & Gamble Company, Cincinnati, Ohio 45239
Received October 24, 1995; Revised Manuscript Received December 27, 1995X
ABSTRACT: Ordered diblock copolymer blends have recently become the subject of tremendous research
interest since they can be used to elucidate the intramicrodomain segregation of blocks differing in length,
as well as to identify the molecular and blend parameters yielding phase immiscibility. In this work, we
explore the influence of molecular architecture on block copolymer blend miscibility by examining an
equimolar mixture of two symmetric styrene (S)/isoprene (I) block copolymers, one an SI diblock and the
other an (SI)4 octablock. Their molecular weights are identical, so that the ratio of block lengths is 4:1
SI:(SI)4. While this ratio is expected to yield a single phase in diblock copolymer blends, transmission
electron microscopy reveals here that the diblock/multiblock blend is macrophase-separated due to the
linear multiblock architecture and midblock conformations of the (SI)4 copolymer. Electron tomography
(3D imaging) permits direct visualization of connected SI and (SI)4 microdomains at the SI/(SI)4 interface


Source: Agard, David - Department of Biochemistry and Biophysics, University of California at San Francisco


Collections: Biotechnology; Biology and Medicine