Enhancing polymer/graphene oxide gas barrier film properties by introducing new crystals

A transparent, gas barrier film comprised of poly(vinyl alcohol) (PVA) and graphene oxide (GO) is synthesized through combined methods of solution blending and isothermal recrystallization. The recrystallized PVA/GO film with only 0.07 vol% GO gives an O2 transmission rate <0.005 cc m−2 day−1 and an O2 permeability <5.0 × 10−20 cm3 cm cm−2 Pa−1 s−1; hence, it is far superior to other blend polymer/inorganic composites. The excellent O2 barrier properties are attributed to a unique hybrid of PVA crystals and GO sheets. PVA crystals form around the GO during isothermal recrystallization, indicating that a GO sheet can act as a nucleating agent. The newly formed PVA crystals fill in the spaces between the GO sheets, and together they become ultra-large impermeable regions, which can prevent the passage of O2. The hybrid film has potential applications in flexible electronics, pharmaceuticals, and food packaging.