Polytetrahydrofuran

Polytetrahydrofuran (PTHF), also known as poly(tetramethylene ether) glycol (PTMEG) or poly(tetramethylene oxide), is a polyether polymer formed from tetrahydrofuran monomer units linked by ether bonds. It has two terminal hydroxyl groups, giving it the properties of a diol. PTHF is available in a range of molecular weights, typically described by its number-average molecular weight (Mn), which can be tailored for specific applications.

The structure of PTHF results in a highly flexible polymer with a very low glass transition temperature, well below room temperature. This high flexibility makes PTHF an important soft-segment component in polyurethanes and other elastomeric materials. The polymer exhibits good compatibility with a wide range of isocyanates, enabling its use in polyurethane foams, coatings, adhesives, and elastomers. In these applications, PTHF imparts elasticity, resilience, and low-temperature performance. It is also used as a plasticizer and as a component in lubricant formulations.

Production of PTHF is typically achieved through living cationic polymerization of tetrahydrofuran using Lewis acid catalyst systems, such as boron trifluoride complexes, under controlled conditions. The polymer is then terminated to yield a diol with hydroxyl end groups, suitable for reaction with isocyanates in polyurethane synthesis. The resulting products are marketed in various grades, with different Mn values to suit rigid foams, flexible foams, coatings, or elastomeric applications.

Safety and handling considerations reflect those of polyether glycols and the THF monomer from which they are derived. THF is highly flammable and can form peroxides; PTHF should be handled with standard industrial hygiene practices, stored away from ignition sources, and used according to supplier and regulatory guidelines.