Blends of poly(vinyl alcohol) (PVA), polyethyleneimine (PEI), and graphene oxide (GO) were prepared by solution casting method. Calorimetric thermal properties of the blends were investigated. The Tgs of PVA/PEI blends were higher than the Tgs of either of the component polymers at low concentrations of PEI. These abnormal increases of Tgs may be due to the negative entropy of mixing which is associated with strong hydrogen bonding between PVA and PEI. The degree of depression of T0ms was not reduced by the negative entropy of mixing, since strong hydrogen bonding also causes an increase in the magnitude of negative χ between PVA and PEI. The Tg of PVA was increased significantly by adding 0.7 wt.% GO into PVA. The magnitude of negative χ was increased by adding GO into the blends of PVA and PEI.

We prepared ethylene vinyl alcohol (EVOH)/graphene oxide (GO) membranes by solution casting method. X-ray diffraction analysis showed that GOs were fully exfoliated in the EVOH/GO membrane. The glass transition temperatures of EVOH were increased by adding GOs into EVOH. The melting temperatures of EVOH/GO composites were decreased by adding GOs into EVOH, indicating that GOs may inhibit the crystallization of EVOH during non-isothermal crystallization. However, the equilibrium melting temperatures of EVOH were not changed by adding GOs into EVOH. The oxygen permeability of the EVOH/GO (0.3 wt%) film was reduced to 63% of that of pure EVOH film, with 84% light transmittance at 550 nm. The EVOH/GO membranes exhibited 100 times better (water vapor)/(oxygen) selectivity performance than pure EVOH membrane.