Polyesterethers

Polyesterethers are polymers that incorporate both ester and ether linkages in their backbone or side chains, typically as copolymers or block copolymers that combine polyester segments with polyether segments. The ester groups provide rigidity and thermal strength, while ether groups impart flexibility and low-temperature performance.

Synthesis of polyesterethers commonly involves condensation or transesterification polymerization of diols with dicarboxylic acids or their derivatives, using diol components that include both aliphatic or aromatic diols and polyether diols such as ethylene glycol, diethylene glycol, or polyethylene glycol. Alternatively, polyesterether segments can be integrated by incorporating polyether diols into polyester-forming reactions, or by ring-opening polymerization of cyclic esters in the presence of ether-containing comonomers.

Properties of polyesterethers depend on the relative content of ester versus ether linkages. Higher ester content tends to increase rigidity, temperature resistance, and solvent resistance, while higher ether content improves flexibility, impact resistance, and low-temperature performance. They often exhibit good adhesion and compatibility with coatings, and can be processed as thermoplastics or thermoplastic elastomers.

Applications include coatings, sealants, and adhesives; resins for electronic encapsulation; soft segments in polyurethane elastomers; and UV-curable resins and optical coatings. In polyurethane chemistry, polyester ether polyols are common starting materials.

Limitations may include hydrolytic susceptibility of ester bonds under high humidity or acidic conditions, and potential phase separation if the polyether and polyester segments are poorly compatible.