hBN Flake Embedded Al2O3 Thin Film for Flexible Moisture Barrier

Due to the vulnerability of organic optoelectronic devices to moisture and oxygen, thin-film moisture barriers have played a critical role in improving the lifetime of the devices. Here, we propose a hexagonal boron nitride (hBN) embedded Al2O3 thin film as a flexible moisture barrier. After layer-by-layer (LBL) staking of polymer and hBN flake composite layer, Al2O3 was deposited on the nano-laminate template by spatial plasma atomic layer deposition (PEALD). Because the hBN flakes in Al2O3 thin film increase the diffusion path of moisture, the composite layer has a low water vapor transmission ratio (WVTR) value of 1.8 × 10−4 g/m2 day. Furthermore, as embedded hBN flakes restrict crack propagation, the composite film exhibits high mechanical stability in repeated 3 mm bending radius fatigue tests.

Case study of fungal growth on newly cast concrete floors

In several cases, the Danish Technological Institute has experienced widespread fungal growth on newly cast concrete floors, with a moisture barrier and floating wooden flooring. The reason for fungal growth is usually due to an inadequate drying period. Existing recommendations require that the relative humidity (RH) of air in equilibrium with the concrete, measured in the middle of the concrete, should not exceed 85-90% RH. In this study, six randomly picked apartments in a newly built apartment complex, were chosen for a case study of fungal growth and moisture on newly cast concrete. The study demonstrates that at least some pecies of fungi can grow very well on newly cast concrete if the surface is dusty and moist. The study also demonstrates that a few samples on the surface will often be representative for the whole floor. The study finds that there is a need to revise the existing guidelines for acceptable moisture content in the concrete before mounting the floor. This might have an impact on the entire building process and/or the design of the floor construction. The study also finds that there is a need for a guideline for measuring moisture and fungal growth on newly cast concrete floors.