What is the material of the raincoat and why is it rainproof?

Update:14 Jan
What is the material of the raincoat? Why is it rainproof? Raincoats are sewn from waterproof fabrics such as tape, tarpaulin, plastic film, including the latest Polytetrafluoroethylene (PTFE) waterproof breathable laminated fabrics.
The principle of waterproofing of raincoats: The materials and styles of modern raincoats are more and more, but no matter how they are changed, there is one property of raincoats that has never changed, that is, rainwater drops on it will quickly gather into small water droplets and flow away. That's exactly why raincoats are waterproof.
When a drop of liquid falls on a solid surface, the liquid will have two different states depending on the attraction between molecules of different materials and the attraction between molecules inside the liquid. When the attractive force of the molecules between the liquid and the solid is smaller than that of the molecules inside the liquid, the droplet tends to shrink into a small droplet on the surface of the solid; when the attractive force of the molecules between the liquid and the solid is greater than that of the molecules inside the liquid Droplets tend to spread evenly on solid surfaces when there is an attractive force. For the former phenomenon, physicists call it "non-wetting", such as mercury dripping on a glass plate, and the latter phenomenon is called "wetting", such as water dripping on a glass plate. Rain falling on the surface of the raincoat is a phenomenon of non-wetting, because the attraction of rubber molecules to water molecules is far less than the attraction between water molecules, and the water molecules prefer to gather together and roll down the surface of the raincoat. At the same time, there are many small holes in the fabric for making raincoats, but because rainwater does not infiltrate the rubber, it is difficult for water molecules to pass through the raincoat fabric through these small holes, and these small holes do not play a role in organizing the air molecules, which ensures that Breathability of raincoats. Since the key to rain protection of raincoats is the rubber-like cloth surface, the raincoat should also pay special attention not to damage the waterproof layer of the cloth surface during storage, so as to avoid sharp objects from scratching the raincoat, there are two more. One thing needs special attention. First, after washing the raincoat, try to avoid drying it in the sun to prevent the rubber from aging. Rubber is a polymer material with many atomic groups and unsaturated chemical bonds. It reacts with various components in the air, such as oxygen, and this reaction is irreversible; the second is that the raincoat should not be stored with objects such as grease, so as not to contaminate the raincoat with these substances. Knowing that the fabric of a raincoat is dirty can be difficult to wash.