Solvent-induced deflection of polydimethylsiloxane plates: Effects of dimensions and solvent volume

The development of flexible electronics and robots has stimulated interest in the deformation behavior of polymers under liquid environments. In this work, we introduce a "local" method to study the toluene-induced deflection of polydimethylsiloxane (PDMS) plates. Placing a graphite rod on the surface of a PDMS plate, we are able to confine the spreading and evaporation of toluene and the uptake of toluene by the PDMS plate. The local uptake of toluene by a PDMS plate causes the deflection of the PDMS plate, which is dependent on the geometric dimensions of the plate and the toluene volume. An empirical relationship is proposed to correlate the largest deflection of a PDMS plate induced by local uptake of toluene to geometric dimensions of the plate and toluene volume. The approach used in this work provides a simple approach to study the kinetics of the solvent-induced deformation of a polymer, which can contribute to the design and applications of a stimuli-sensitive self-shaping polymer.