Highly stretchable composites from PDMS and polyazomethine fine particles

Abstract

Polyazomethine (PAZ) submicron (fine) particles were obtained by polycondensation reactions occurring in reverse micelles of an amphiphilic siloxane oligomer. These particles were used as a dispersed phase of 10–40 wt% in a high molecular mass PDMS to obtain all-polymer composites. The new materials were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dielectric relaxation spectroscopy (DRS), contact angle, breakdown and stress–strain measurements. Thin films with a uniform morphology all over the cross-section were obtained. The dielectric permittivity markedly increased (up to 300% at 1 Hz) compared to the pristine PDMS. The PAZ fine particles act as reinforcing fillers for the PDMS matrix. Low loading levels (10–20%) allow the material to be kept within the range of soft elastomers, with a maximum strain of 600–800% and a low Young’s modulus, while higher amounts of fillers limit the strain to around 350%. The dielectric and mechanical properties can be tuned depending on the composition and structure of the dispersed phase. Such materials may be interesting as dielectric elastomer transducers or as highly flexible PDLCs.