Common types of polyether polyols include polytetrahydrofuran glycol (PTHF)-also known as polyoxytetramethylene glycol (PIG, PTMEG, PTMG, or PTMO)-which is produced through the ring-opening polymerization of tetrahydrofuran (THF) in the presence of a cationic catalyst. The production process involves charging a reactor with THF, cooling the mixture to below -5°C, and adding fuming sulfuric acid (as a catalyst) dropwise under vigorous stirring while maintaining a low temperature. Subsequently, a specific amount of water is added under stirring, and the temperature is raised to 70–90°C. Unreacted THF monomer is distilled off, and the product undergoes phase separation (via settling), neutralization, filtration, and vacuum treatment to yield polytetrahydrofuran glycol.
Due to its relatively high cost, polytetrahydrofuran glycol is typically used to manufacture high-performance polyurethane materials; the resulting products exhibit excellent resistance to low temperatures, water, oil, abrasion, and mold. Tetrahydrofuran-propylene oxide copolymer glycol is produced via the ring-opening copolymerization of THF and propylene oxide catalyzed by a Lewis acid, followed by neutralization, water washing, dehydration, and filtration. Its structural formula is as follows: [Structural formula/Product specifications for tetrahydrofuran-propylene oxide copolymer glycol]. This copolymer ether is less expensive than pure polytetrahydrofuran glycol, yet its product properties are comparable to those of PTMG; it is particularly suitable for manufacturing low-temperature resistant polyurethane materials (capable of withstanding temperatures as low as -200°C).
