Controlling nanowear in a polymer by confining segmental relaxation.

Nano Lett

IBM Research GmbH, Zurich Research Laboratory, 8803 Rüschlikon, Switzerland.

Published: February 2006

Molecular relaxation of a copolymer designed for nano-electromechanical systems was chemically confined by varying the spacing between cross-links, delta(c). A critical cross-link spacing of 1-3 nm marks a transition in the nano-mechanical properties evaluated by atomic force microscopy. The transition reveals an interplay between the cross-link spacing and the length scale for backbone relaxation, xi(alpha), in cooperatively rearranging regions. For delta(c) >> xi(alpha), the natural backbone relaxation process is relatively unaffected by the cross-links and a ductile, low hardness behavior results. For delta(c) < xi(alpha), the cross-links directly interfere with backbone relaxation and confine segmental mobility, leading to a brittle, high hardness response.

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http://dx.doi.org/10.1021/nl0520563DOI Listing

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