Amine-Terminated Polyethers

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Amine-terminated polyethers are polyamines with a polyether main chain, also known as “polyether polyamines.” Currently, most amine-terminated polyethers on the market are the amination products of secondary hydroxyl-terminated polyether diols or triols (including PPG and PO-EO copolymers). They are aliphatic polyether amines, with primary amino groups predominantly at the termini. Because the reactivity of amino groups with isocyanates is much higher than that of hydroxyl groups, polyether polyamines are highly reactive polyethers. There are also a small number of polyether amines obtained by converting amino groups to secondary amino groups. There are also special amine-terminated polyethers with a PTMEG main chain and aromatic amino groups at the termini.

Polyoxypropylenediamine has a CAS number of 9046-10-0, with representative products including the Jeffamine D series. Polyoxypropylene triamine, initiated with glycerol, has a CAS number of 64852-22-8, with representative products including T-3000 and T-5000. Polyoxypropylene triamine, initiated with trimethylolpropane, has a CAS number of 39423-51-3, with a representative product being T-403. Polyoxyethylene-polyoxypropylene diamine (PPG-PEG-PPG copolymer diamine) has a CAS number of 65605-36-9, with representative products including the Jeffamine ED series. PPG-PTMEG-PPG block copolymer diamine has a CAS number of 796093-55-5, with representative products including Jeffamine THF-100 and THF-140. Polytetrahydrofuran diamine has a CAS number of 960525-56-8, with a typical product being Jeffamine THF-170.

The structural formula of Jeffamine ED series and other copolyether diamines is as follows:

A special end-functionalized amine ether has the chemical name polytetramethylene ether di-p-aminobenzoate, with CAS number 54667-43-5. Typical products include Versalink P-250, P-650, and P-1000 from Air Products. Its structural formula is as follows:

Physical and Chemical Properties

Polyether diamines and polyether triamines are typically colorless to light yellow liquids with a slight amine odor and low to medium viscosity. Low molecular weight or high EO content polyether polyamines are soluble in water, while medium to high molecular weight polyoxypropylene polyamines are generally insoluble in water. Dilute aqueous solutions of polyether polyamines are alkaline, with a pH value between 10 and 11.5.

Ordinary end-functionalized polyethers contain a small amount of hydroxyl groups that are not aminated, generally between 2% and 5%. Both hydroxyl groups and primary and secondary amine groups react with isocyanate groups, and their total amount can be determined by acetylation.

Characteristics and Applications

Spray-applied polyurea elastomers prepared from end-functionalized polyethers and isocyanates have high strength, high elongation, excellent abrasion resistance, corrosion resistance, and aging resistance. They are widely used in waterproof, anti-corrosion, and wear-resistant coatings for concrete and steel structures, as well as protective and decorative coatings for other components.

End-functionalized polyethers are used as epoxy resin curing agents, improving the toughness of the products. Lower molecular weight end-functionalized polyethers are widely used as epoxy resin curing agents, as well as in polyamides and antistatic agents.

The end groups of polyether polyamines are generally primary amines, which are more reactive than primary hydroxyl groups and react rapidly with isocyanate groups. Huntsman has recently introduced the Jeffamine SD/ST series, which are secondary amine polyether diamines with lower reactivity, suitable for use in polyurethanes.