Tunable electrical and mechanical responses of PDMS and polypyrrole nanowire composites

Journal of Physics D: Applied Physics

Ping Du, Xi Lin, Xin Zhang

Volume 46, Number 19, Page 195303

doi:10.1088/0022-3727/46/19/195303

A generic experimental procedure is presented in this work to enhance
the electrical responses of polydimethylsiloxane (PDMS) through
incorporation of conducting polymer nanowires, while maintaining the
desirable mechanical flexibility of PDMS. The conducting polypyrrole
(PPy) nanowires are synthesized using a template method. The dielectric
constants of the composites are characterized by impedance measurements,
and the effect of nanowire concentration is investigated by the
percolation theory. Using a continuous hyperbolic tangent function,
critical volume fraction is estimated to be 9.6 vol%, at which an
85-fold enhancement in the dielectric constants is achieved. The
viscoelastic properties of the composites are characterized by the
stress relaxation nanoindentation tests, and the effect of nanowire
concentration on the elastic modulus of composites is found to deviate
significantly from the Wang–Pyrz model at the critical volume fraction.
The tunable multifunctionality of PDMS composites that possess
significantly enhanced electrical and moderate viscoelastic responses is
desirable for many sensing and actuation applications.