ABSTRACT
Biomass chitosan has garnered considerable interest for alkaline anion exchange membranes (AEMs) due to its eco-friendly and sustainable characteristics, low reactant permeability and easily modifiable nature, but it still faces the trade-off between high hydroxide conductivity and sufficient mechanical properties. Herein, a novel functionalized attapulgite clay (f-ATP) with a unique ionic "chain-ball" surface structure was prepared and incorporated with quaternized chitosan (QCS)/polyvinyl alcohol (PVA) matrix to fabricate high-performance composite AEMs. Due to the strengthened interfacial bonding between f-ATP nanofillers and the QCS/PVA matrix, composite membranes are synergistically reinforced and toughened, achieving peak tensile strength and elongation at break of 24.62 MPa and 33.8 %. Meanwhile, abundant ion pairs on f-ATP surface facilitate ion transport in the composite AEMs, with the maximum OH- conductivity of 46 mS cm-1 at 80 °C and the highest residual IEC of 83 % after alkaline treatment for 120 h. Moreover, the assembled alkaline direct methanol fuel cell exhibits a remarkable power density of 49.3 mW cm-2 at 80 °C. This work provides a new strategy for fabricating high-performance anion exchange membranes.
Subject(s)
Chitosan , Clay , Magnesium Compounds , Membranes, Artificial , Polyvinyl Alcohol , Silicon Compounds , Chitosan/chemistry , Polyvinyl Alcohol/chemistry , Magnesium Compounds/chemistry , Silicon Compounds/chemistry , Clay/chemistry , Anions/chemistry , Ion Exchange , Tensile Strength , Surface PropertiesABSTRACT
Thermally conductive and electrically insulating composites are important for the thermal management of new generation integrated and miniaturized electronic devices. A practical and eco-friendly electrostatic self-assembly method was developed to prepare boron nitride-multilayer graphene (BN-MG) hybrid nanosheets. Then, BN-MG was filled into silicone rubber (SR) to fabricate BN-MG/SR composites. Compared with MG/SR composites with the same filler loadings, BN-MG/SR composites exhibit dramatically enhanced electrical insulation properties while still maintaining excellent thermal conductivity. The BN-MG/SR with 10 wt.% filler loading shows a thermal conductivity of 0.69 W·m-1·K-1, which is 475% higher than that of SR (0.12 W·m-1·K-1) and only 9.2% lower than that of MG/SR (0.76 W·m-1·K-1). More importantly, owing to the electron blocking effect of BN, the electron transport among MG sheets is greatly decreased, thus contributing to the high-volume resistivity of 4 × 1011 Ω cm for BN-MG/SR (10 wt.%), which is fourorders higher than that of MG/SR (2 × 107 Ω·cm). The development of BN-MG/SR composites with synergetic properties of high thermal conductivity and satisfactory electrical insulation is supposed to be a promising candidate for practical application in the electronic packaging field.
