Electrical box insulation

It is said that much air leaks into or out of a home's conditioned spaces through light fixtures and switches, etc. While there are foam gaskets for switches and recepticals, I have not seen foam gaskets for multiple switches or recepticals, nor have I seen them for light fixture boxes. The product I propose is a closed-cell expanding foam. It would be formulated to be fireproof or highly fire resistant (maybe made of minerals instead of plastic?) and would not stick to surfaces as existing expanding foam products do. The idea is to just fill the electrical box with this foam, which would seal it up but still allow the foam to be removed easily when wiring needs to be done. A sticky version could be used to seal around the edge of the box.