Polyurethane elastomers from PTHF

In a recent patent, Reuter (110) describes a polyurethane prepared from PTHF (mol. wt. 1000 to 3000), 1,4-butanediol, and OCN(CH2)6CN0. In another case Murbach and Adicoff (67) interrupted the regularity of PTHF by copolymerization with ethylene oxide before chain extension with diphenyl-methane-4,4 -disiocyanate. Dickinson (99) prepared a series of polyurethane elastomers from THF-PO copolymer diols and 2,4-tolylene diisocyanate. He found that the use of copolymers with approximately 75 wt.-% THF led to polyurethanes with very good properties relative to the use of propylene oxide homopolymer. 

Thus, from high MW diols (MW = 1000-4000 daltons) polyethers (polyalkyleneoxides, polytetrahydrofuran (PTHF)), polyesters, polycarbonates (PC), polybutadienes, etc., by the reaction with diisocyanates [toluene diisocyanate (TDI), or pure diphenyl methane diisocyanate (MDI)], high MW linear polyurethanes are obtained (no crosslinking), with high elasticity (polyurethane elastomers, spandex fibres, some adhesives and sealants, etc). 

Polytetrahydrofuran (polytetramethylene ether, PTHF) n, A type of polycol made from tetrahydrofuran by ring opening, have the mer [-CH2(CH2)3-0-] and -OH end groups, with low to moderate molecular weights. These polymers have long been used as pre-polymers for polyurethane elastomers. 

High molecular weight PTHF has excellent elastomeric properties but its price is four to five times higher than that of usual rubbers. However, low molecular weight glycols, which are easily prepared from THF and are very useful for the preparation of polyurethanes and polyester thermoplastic elastomers, has been commercially developed inspite of these high costs. 

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