Controlling nanowear in a polymer by confining segmental relaxation.
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.
Gotsmann
Bernd
B
IBM Research GmbH, Zurich Research Laboratory, 8803 Rüschlikon, Switzerland. bgo@zurich.ibm.com
Duerig
Urs T
UT
Sills
Scott
S
Frommer
Jane
J
Hawker
Craig J
CJ
D018625:Microscopy, Atomic Force / Q000379:methods; D015394:Molecular Structure; D043942:Nanotubes / Q000737:chemistry*; D010316:Particle Size; D011083:Polycyclic Compounds / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013499:Surface Properties
D011083:Polycyclic Compounds; D011108:Polymers; D011137:Polystyrenes; C079040:benzocyclobutene