Waterproof breathable layers - A review.

Waterproof breathable layers (WPBLs) can be classified into two large groups of hydrophilic nonporous and hydrophobic porous layers. These layers (e.g., fabrics, films, membranes, and meshes) can be produced by various continuous and non-continuous processes such as coating, laminating, film stretching, casting, etc. The most common methods for production, characterization, and testing of WPBLs are presented and discussed in light of recent publications. The materials with high level of waterproofness and breathability are often used in outerwear for winter sports, sailing apparel, raincoats, military/police jackets, backpacks, tents, cargo raps, footwear and etc. WPBLs can also be used for other specialized applications such as membrane distillation, oil-water filtration, and wound dressing. These applications are discussed by presenting several good examples. The main challenge in the production of these layers is to compromise between waterproofness and breathability with opposing nature. The related research gaps, challenges, and future outlook are highlighted to shed more light on the topic.