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Structure of Microphase-Separated Silica/Siloxane Molecular Composites

Published online by Cambridge University Press:  21 February 2011

Dale W. Schaefer ,
James E. Mark ,
David Mccarthy ,
Li Jian ,
C. -C. Sun  and
Bela Farago
Dale W. Schaefer
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185, USA
James E. Mark
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185, USA
David Mccarthy
Affiliation:
Department of Chemistry and the Polymer Research Center, The University of Cincinnati, Cincinnati, OH 45221, USA
Li Jian
Affiliation:
Department of Chemistry and the Polymer Research Center, The University of Cincinnati, Cincinnati, OH 45221, USA
C. -C. Sun
Affiliation:
Department of Chemistry and the Polymer Research Center, The University of Cincinnati, Cincinnati, OH 45221, USA
Bela Farago
Affiliation:
Insititut Laue-Langevin, 38042 Grenoble, France
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Abstract

The structure of several classes of silica/siloxane molecular composites is investigated using small-angle x-ray and neutron scattering. These filled elastomers can be prepared through different synthethic protocols leading to a range of fillers including particulates with both rough and smooth surfaces, particulates with dispersed interfaces, and polymeric networks. We also find examples of bicontinuous filler phases that we attribute to phase separation via spinodal decomposition. In-situ kinetic studies of particulate fillers show that the precipitate does not develop by conventional nucleation-and-growth. We see no evidence of growth by ripening whereby large particles grow by consumption of small particles. Rather, there appears to be a limiting size set by the elastomer network itself. Phase separation develops by continuous nucleation of particles and subsequent growth to the limiting size. We also briefly report studies of polymer-toughened glasses. In this case, we find no obvious correlation between organic content and structure.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 171: Symposium O – Polymer Based Molecular Composites , 1989 , 57
Copyright
Copyright © Materials Research Society 1990

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References

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