Solubility in Polymers, Glasses, and Ceramics:

Hydrogen gas dissolves as the molecular hydrogen species in several materials.  For these systems, solubility is commonly endothermic and is straightly proportional to gaseous overpressure. The materials in that hydrogen dissolve as the molecular species involve glasses and organic polymers at less than 150º C. Organic polymers commonly have atomic-scale voids within the twisted polymer chain, and the hydrogen molecules find these sites. Hydrogen dissolution in glasses is supposed to be same.