Abstract
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The low-voltageelectromechanicalactuationofpolypyrrole(PPy)dopedwithdi-(2-ethylhexyl)
sulfosuccinate (DEHS)hasbeeninvestigated.ThePPy-DEHShasbeenpreparedbothchemically(cast
as filmsfromsolution)andbymoreconventionalelectrochemicalpolymerization.Verylargestrainsof
∼30% wereobtainedduringslow-scanredoxcyclingoftheelectrochemicallypreparedPPy-DEHSfilms.
In constrast,PPy-DEHSfilmscastfromsolutionsofthechemicallypolymerizedpolymergaveactuation
strains of ∼2.5%. Thepolymerizationmethodwasalsofoundtohaveasignificanteffectonthestructure,
conductivity andmechanicalpropertiesofthePPy-DEHSmaterials.Theconductivityoftheelectrochem-
ically polymerizedPPy-DEHSwas75Scm−1, considerablyhigherthanthatfoundforthechemically
derived polymer(7Scm−1). ThestructureofthePPy-DEHSwasfurtherelucidatedfromUV–vis,Raman
and FT-IRspectralstudieswhichindicatedthattheconjugationlengthofthePPycouldbeincreased
significantly byvaryingthepolymerizationmethod.FilmsobtainedbycastingchemicallypreparedPPy-
DEHS showedhighermodulus(2.3GPa)thanelectropolymerizedPPy-DEHS(0.6GPa),butweremore
brittle. Bothmaterialswereelectroactiveinacetonitrile/waterelectrolyte.Thehigheractuationstrain
observed intheelectrochemicallypreparedfilmswasattributedtoamoreopenmolecularstructure(as
indicated bythelowermodulus)allowingforeasieriondiffusionandahigherconductivityallowing
easier chargetransfer.