Electrostatically assembled layer-by-layer composites containing graphene oxide for enhanced hydrogen gas barrier application

Hydrogen gas barrier properties of polymeric materials are a critical determinant of their practical use in hydrogen gas storage and transportation container applications. We fabricated multi-layered films containing poly(diallyldimethylammonium) chloride (PDDA) and sulfonated polyvinylidene fluoride (SPVDF)-graphene oxide (GO) composites through layer-by-layer (LBL) assembly to enhance the hydrogen gas barrier properties. Polyethylene terephthalate (PET) substrate was rendered hydrophilic by treatment with aqueous sodium hydroxide solution prior to LBL assembly construction. Positively-charged PDDA and negatively-charged SPVDF or SPVDF/GO composites were assembled by spin-coating and were tightly packed by electrostatic attraction. LBL assemblies were characterized by Fourier transform infrared (FT-IR) spectroscopy and Field emission scanning electron microscopy (FE-SEM) analyses. Electrostatic LBL assembled PDDA/SPVDF-GO films showed improved mechanical and gas barrier properties compared to their respective PDDA/SPVDF LBL assemblies without GO. The hydrogen gas transmission rate (GTR) of a 16 bi-layer LBL assembly with 2 wt.% GO was 11.7 cc/m2 d atm, which was much lower than that of PET substrate (329.1 cc/m2 d atm) and a one bi-layer LBL assembly without GO (277.9 cc/m2 d atm). The drastic decrease in GTR indicates that LBL assembled films are suitable for use in high hydrogen barrier applications.