{TAIL ~ The hydrocarbon groups} generally are {HEAD ~ alkyl groups} which may be straight or branched and may optionally be substituted with phenyl 
{ TAIL ~ The hydrocarbon groups } generally are { HEAD ~ alkyl groups } which may be straight or branched and may optionally be substituted with phenyl
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH