{HEAD ~ The comonomer} may be {TAIL ~ a nonpolar, ionic, polar comonomer} or mixtures of such monomers 
be
{ HEAD ~ The comonomer } may be { TAIL ~ a nonpolar , ionic , polar comonomer } or mixtures of such monomers
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH