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Elastomeric Light Emitting Polymer Enhanced by Interpenetrating Networks
journal contribution
posted on 2016-11-04, 00:00 authored by Huier Gao, Si Chen, Jiajie Liang, Qibing PeiConjugated
polymers containing long-chain alkyl side groups for solubility are
generally unstretchable: large strain induces crack formation, fracture,
or plastic deformation. When the polymers are stretched to reorient
the conjugated chains along the stretching direction, high dichroic
ratio is observed both for absorption of the ground state and radiative
decay of the excited state. Here an interpenetrating polymer network
(IPN) approach is reported to impart elastomeric deformability to
a conjugated polymer. A soluble alkyloxy phenyl substituted poly(1,4-phenylenevinylene)
(SY-PPV) with bright yellow fluorescent emission was admixed with
an ionically conductive medium containing poly(ethylene oxide), exoxylated
trimethylolpropanetriacrylate, and lithium trifluoromethanesulfonate.
The spin-cast blend film formed an IPN morphology wherein SY-PPV forms
a porous network with pores filled by the ionic medium. PeakForce
quantitative nanomechanical mapping showed that the local Young’s
modulus was high in the SY-PPV phase, while the ionic phase was two-times
softer. No global polarization of the SY-PPV chains was observed at
strains up to 100% as the dichroic ratio remains close to 1. Light-emitting
devices based on the blend sandwiched between two stretchable transparent
composite electrodes could be stretched by up to 140% strain. No electroluminescence
polarization was observed.