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The Effect of Polymer Chain Alignment and Relaxation on Force‐Induced Chemical Reactions in an Elastomer
Author(s) -
Beiermann Brett A.,
Kramer Sharlotte L. B.,
May Preston A.,
Moore Jeffrey S.,
White Scott R.,
Sottos Nancy R.
Publication year - 2014
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201302341
Subject(s) - materials science , spiropyran , merocyanine , polymer , birefringence , elastomer , stress (linguistics) , acrylate , ultimate tensile strength , stress relaxation , deformation (meteorology) , composite material , optics , copolymer , nanotechnology , linguistics , philosophy , physics , creep , photochromism
Simultaneous measurements of mechanical response, optical birefringence, and fluorescence signal are acquired in situ during tensile testing of a mechanophore‐linked elastomeric polymer. Mechanical stress, deformation, and polymer chain alignment are correlated with force‐induced chemical reaction of the mechanophore. The mechanochemically responsive polymer under investigation is spiropyran‐ (SP‐) linked poly(methyl acrylate) (PMA). Force‐driven conversion (activation) of SP to its merocyanine (MC) form is indicated by the emergence of a fluorescence signal with 532 nm light incident on the sample. Increasing rate of tensile deformation leads to an increase in both stress and SP‐to‐MC conversion, indicating a positive correlation between macroscopic stress and activation. Simultaneously collected birefringence measurements reveal that rapid mechanophore activation occurs when maximum polymer chain alignment is reached. It is found that SP‐to‐MC conversion in PMA requires both a sufficient level of stress and adequate orientation of the polymer chains in the direction of applied force.