More preferably, {TAIL ~ the polymer} has {HEAD ~ a molecular weight} no greater than 60 kDa 
More preferably , { TAIL ~ the polymer } has { HEAD ~ a molecular weight } no greater than 60 kDa
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH