Types of rubber used with Rolex seals

[SpicyMikey]

Here's a strange question but I want to know since I deal with some caustic chemicals sometimes. Easy solution is to keep my watch away from such chemicals, but that still doesn't satisfy the curiosity!

Any of our experts know more specifically what materials are used for these various O rings, gaskets, etc, in a newer rolex? Certain it is not natural rubber, but what type of synthetic rubber do they use? Butyl, Neoprene, EPDM, Silicone, etc. Thanks!