As noted, one of {HEAD ~ the dicarboxylic acids} must have {TAIL ~ an aryl group}, which acid would include but not be limited to terephthalic acid and isophthalic acid 
have
As noted , one of { HEAD ~ the dicarboxylic acids } must have { TAIL ~ an aryl group } , which acid would include but not be limited to terephthalic acid and isophthalic acid
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH