The present invention relates to a composition comprising a binder comprising one or more siloxane polymers, silicone resins, silicone based elastomers, and mixtures thereof, wherein said binder optionally comprises one or more cross-linker components comprising a silane and/or a siloxane containing silicon-bonded hydrolysable groups; and a hydrophilic powder and/or gel selected from one or more amorphous, porous hydrophilic silica (s) having a thermal conductivity at 20° C. and atmospheric pressure of 0.001 to 0.15 W/m·K and a surface area (SBET) of between 200 and 1500 m