wherein m and n are integers and {TAIL ~ R} is a substituted or unsubstituted alkyl or {HEAD ~ aryl group} 
wherein m and n are integers and { TAIL ~ R } is a substituted or unsubstituted alkyl or { HEAD ~ aryl group }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD