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