In organic chemistry, a carbomer is an expaned molecule obtained by insertion of a C2 unit in a given molecule . Carbomers differ from their templates in size but not in symmetry when each C–C single bond is replaced by at least one alkyne bond, and when a double bond is replaced by an allene bond. The size of the carbomer will continue to increase when more alkyne bonds are introduced and for this reason carbomers are also called carbon-molecules, where "n" is the number of acetylene or allene groups in an n-expansion unit. This concept, devised by Remi Chauvin in 1995, is aimed at introducing new chemical properties for existing chemical motifs.