Abstract:

Partially crosslinked and sulfonated poly(vinyl alcohol) (s-PVA) membranes were prepared as ion-conductive matrices of Ionic Polymer-Metal Composite (IPMC) and a new IPMC based on the s-PVA membrane was fabricated via an electroless plating procedure of platinum. PVA was reacted with sulfosuccinic acid (SSA) as a crosslinking agent with a sulfonic group and 4-(2-hydroxyethyl)piperazine-1-propanesulfonic acid (EPPS) as a side chain with a sulfonic group. The crosslinked s-PVA membranes were characterized using a FT-IR spectroscope and a scanning electron microscope-combined energy-dispersive X-ray spectrometer and were assessed in terms of water absorption, proton conductivity, and the feasibility of electroless plating. Among the prepared ionomers, the s-PVA membrane obtained at 20 wt.% SSA and 10 wt.% EPPS (S20E10 membrane) registered the highest proton conductivity of 2.9 ? 10−2 S•cm−1, which corresponds to one third of that of Nafion series, and only the S20E10 membrane was successfully plated via the electroless plating method without any crack and broken part. The s-PVA-based IPMC showed the one-directional displacement with 1-minute-long time-lapse comparable to typical Nafion-based IPMCs. However, the displacement under an AC potential was very limited due to its slow deformation response and the actuation performance was severely varied with actuation time including the short service life of several minutes in air. The short and variable actuation of the s-PVA-based IPMC was attributed to its large variation of surface and ionic resistances during air-operation, which is induced by the low ratio of bound to free water.

Key words: ionic polymer-metal composite, actuators, sulfonated poly(vinyl alcohol)