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