Thermal Conductivity of PDMS Filled with Hollow Glass Microspheres

Polydimethylsiloxane (PDMS) is the most widely used silicon-based polymer due to its versatility and the range of attractive properties. Fabrication of PDMS involves liquid phase cross-linking to obtain hydrophobic and mechanically flexible material in the final solid form. This gives opportunity to add various fillers to affect the properties of resulting material. In the present work, we describe simple and reliable method of making a PDMS-based composite material with significantly improved thermal insulation properties by adding hollow glass microspheres (HGMs) to the mixture of liquid base and cross-linker (10:1 ratio) followed by degassing and heat-assisted crosslinking. We obtained 31% reduction of thermal conductivity for samples with HGMs content of 20% by mass. At the same time, sound insulation capacity slightly decreased as a result of lower density of PDMS-HGMs composite in comparison to pure PDMS. The wettability of the samples had no dependence on HGMs content.