Preferred polymers of formula further include polymers where R is a polyalkylene oxide, i.e., R together with the oxygens to which it is attached forms a bridging polyol, such as {HEAD ~ polytetramethylene ether}, polypropylene oxide, polyethylene oxide, other polyalkylene oxides, including polyalkylene oxides containing {TAIL ~ mixed length alkylenes} 
Preferred polymers of formula further include polymers where R is a polyalkylene oxide , i.e. , R together with the oxygens to which it is attached forms a bridging polyol , such as { HEAD ~ polytetramethylene ether } , polypropylene oxide , polyethylene oxide , other polyalkylene oxides , including polyalkylene oxides containing { TAIL ~ mixed length alkylenes }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL