Most preferably, the polymer has a molecular weight in {HEAD ~ the range} of {TAIL ~ 15 kDa} to 40 kDa 
of
Most preferably , the polymer has a molecular weight in { HEAD ~ the range } of { TAIL ~ 15 kDa } to 40 kDa
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH