US Patent 8092878 Cryogenic, elastomeric closure for cryogen containers

A multi-material, cryogenic, elastomeric closure is provided for sealing a container for samples of cryophilic biological materials, pharmaceuticals or the like. The closure includes at least one cryophilic elastomer having a glass transition temperature (Tg) below the cryogenic temperature to which the sample is to be subjected and at least one non-cryophilic elastomer having a Tg above the cryogenic temperature. The cryophilic and non-cryophilic elastomers are present in such a manner as to maintain a complete seal of the container opening at the cryogenic temperature.