Microporous coatings and films

Microporous membranes are defined as having a narrow pore-size distribution, normally in the sub-micrometre range, although they can range from 0.1 to 10 micrometres. It is common for microporous films to have 1 - 2 billion pores per square centimetre in a film 10 - 50 micrometres thick. The most widely used polymers for microporous fabrics are polyurethanes and polytetrafluoroethylene, but acrylics, polyamino acids and polyolefins are also used.

The pink layer represents the skin and the pale blue spots represent water "vapour" molecules. The molecules are small enough to pass through the micro-pores but the relatively large water droplets are too large to enter the micro-pores. Typical dimensions of water "droplets" (diameter µm): drops of fog 100, drizzle 500, rain 2000, heavy rain 300, water vapour 0.0003.