LIBRARIES
    • Login
    Research Exchange
    Share your work
    View Item 
    •   Research Exchange
    • Electronic Dissertations and Theses
    • Electronic Dissertations
    • View Item
    •   Research Exchange
    • Electronic Dissertations and Theses
    • Electronic Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of Research ExchangeCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Application-driven studies of photomechanical materials

    Thumbnail
    View/Open
    Bernhardt_wsu_0251E_12293.pdf (21.10Mb)
    Date
    2018
    Author
    Bernhardt, Elizabeth Adeline
    Metadata
    Show full item record
    Abstract
    Deep brain stimulation therapy is a well-established medical procedure with well-documented benefits, but this procedure would be enhanced by a flexible therapy device that could bend when photoactivated. To this end, two types of materials, which respond to light by inducing a stress and strain, show promise and are therefore selected to be characterized: photomechanical dye-doped glassy polymer fibers and liquid crystal elastomers. A custom designed and built apparatus, the photorheometer, measures the force created by these materials during photostimulation. Using the developed theory, it is found that the liquid crystal elastomers produce a large strain but small stress while dye-doped glassy polymer fibers produce a large stress but small strain. Photoisomerization in dyes, a mechanism where a molecule changes shape in response to photostimulation, is investigated in dye-doped glassy polymer fibers. Results show glassy polymer fibers doped with isomerizable dyes have a notable polarization dependence, but this dependence cannot be fully explained by isomerization alone, as non-isomerizable dyes also have a polarization dependence. Liquid crystal elastomers from two synthesis methods are characterized. The first method creates side-chain end-on siloxane-based liquid crystal elastomers, and the second method is a two-stage procedure creating main-chain acrylate-based liquid crystal elastomers. Using the photorheometer, materials made with the different synthesis methods are charactered with various liquid crystalline order. The materials made with the two-stage procedure are also characterized as a function of pre-strain, dye concentration, and crosslink density. Results show monodomain (highly ordered liquid crystal elastomer), low dye concentration, and crosslinked liquid crystal elastomers have a larger photomechanical response than polydomain, high dye concentration (0.25%mol - 1%mol), non-crosslinked liquid crystal elastomers.
    URI
    http://hdl.handle.net/2376/16343
    Collections
    • Electronic Dissertations and Theses - Physics and Astronomy
    • Electronic Dissertations