Metal nanoparticles as an electromagnetic microwave heat-cure agent for polydimethylsiloxane elastomers

Abstract

Most commonly polydimethylsiloxane (PDMS) elastomer (silicone) is obtained from prepolymer liquid by cross-linking reaction (curing) at room temperature or assisted by external heating. However, in special cases, such as medical applications, it could be useful to cure the elastomeric material selectively and / or without external heat. An ability for customized curing can be controlled by selection of special type of fillers, such as metal particles or carbon nanotubes for curing routed via Joule heat, magnetic induction or electromagnetic microwave radiation. There are number of reasons for microwave curing to be preferred: microwave curing does not require heat conductivity of the surrounding medium, microwave energy can be directly delivered to select part of the material, this also allows for energy saving. Dielectric (internal) heating by microwave radiation is not efficient for pristine PDMS due to non-polar nature of this substance. Higher chemical polarity additives to PDMS could facilitate internal heating. We test silver nanoparticles (Ag NPs) for using as internal heating agent for PDMS elastomer kit (Sylgard 184). A set of general properties of the resultant PDMS / AgNPs composite material, including dynamic mechanical analysis (DMA), water wetting contact angle, adhesion to glass and optical spectroscopy of the filled PDMS are evaluated herein. The obtained composite materials exhibit a significantly higher work of adhesion, a lower viscoelastic modulus and slightly higher wettability. With time of microwave treatment and consequently cross-linking of the material those parameters head towards or approach those of the stock PDMS material.