PTMEG

PTMEG, or poly(tetramethylene ether) glycol, is a polyether diol used primarily as a soft, flexible segment in polyurethane formulations. Its repeating unit consists of an ether linkage with four methylene groups, giving a structure of HO–[-O–CH2–CH2–CH2–CH2–]n–OH. The polymer ends in hydroxyl groups, enabling it to react with diisocyanates to form polyurethane networks. PTMEG is also referred to as PTMG (poly(tetramethylene glycol)).

Production of PTMEG is based on the polymerization of tetrahydrofuran (THF) through a cationic ring-opening mechanism. This process typically employs a Lewis acid catalyst, such as boron trifluoride etherate, and difunctional initiators to create dihydroxy-terminated polymers. The resulting PTMEG grades span a range of molecular weights, allowing formulation of products from flexible liquids to higher-viscosity polyols used in coatings, adhesives, and elastomers.

Key properties of PTMEG include a very low glass transition temperature, which imparts excellent low-temperature flexibility to polyurethane systems. The ether backbone contributes to good hydrolytic stability, clarity, and compatibility with a variety of diisocyanates. The material is supplied in various molecular weights to tailor mechanical performance, resilience, and elongation in end-use polyurethanes.

Common applications focus on PTMEG as a soft segment in flexible polyurethane foams, elastomeric polyurethanes, coatings, adhesives, and sealants. By adjusting the PTMEG molecular weight and content, manufacturers can tune Tg, elasticity, and resilience to meet specific performance requirements.