Organosilicon polymer foams are synthesized using a Carboni-Lindsey reaction of a tetrazine with a siloxane polymer having at least one of alkenyl or alkynyl functional groups. Optionally, the reaction may also comprise a second polymer having at least one of alkenyl or alkynyl functional groups. The organosilicon polymer foams may be crosslinked thermoset foams. The foams may be flexible or rubbery.