Preparation and gas barrier properties of cellulose nanocrystal-silica organic–inorganic hybrid gas barrier membranes with crosslinked structures

Cellulose nanocrystal (CNC)-silica organic–inorganic hybrid gas barrier membranes were prepared by sol–gel method, and crosslinked structures of cellulose were introduced by crosslinking reaction using citric acid (CA). The effects of crosslinking agent (CA) content on the gas barrier property of the membranes were investigated. Water vapor transmission rate of C60 (60 wt% CA to CNC) was small (3.6 g m⁻² day⁻¹), which is the same order of poly(vinylidene chloride) (PVDC). Oxygen permeability coefficients of C100 (100 wt% CA to CNC) was one-tenth of that of PVDC. Light transmittance of the organic–inorganic hybrid gas barrier membrane (C60) coated on the PET was 95%. And the pencil hardness of the membrane (C60) coated on the PET indicated HB. For the flexibility test, a 2 mm diameter stainless rod was attached to the membrane, and bent 10 times along the rod circle, no cracks were observed in the membrane surface. The hybrid gas barrier membranes exhibit higher oxygen and water vapor barrier properties with transparency, hardness and flexibility.