Phase separation and physical properties of PEO-containing poly(ether ester amide)s

Poly(ether ester amide) (PEEA) copolymers based on poly(ethylene glycol) (PEG), 1,4- butanediol, and dimethyl-7,12-diaza-6,13-dione-1,18-octadecanedioate (a diester-diamide monomer) were synthesized by a two-step polycondensation reaction. The obtained segmented copolymers are hydrophilic, with a water uptake of 24–340%. PEEA copolymers showed microphase separation, as observed by differential scanning calorimetry (DSC). The long spacing determined by small-angle X-ray scattering shows an increase in the hydrophilic domain size with increasing PEO content. By varying the copolymer composition, the E-modulus of PEEA could be varied between 61 and 427 MPa, with tensile strengths ranging from 12 to 39 MPa. The elongation at break can reach values up to 850%. The mechanical properties decrease with the uptake of water. However, PEEAs with a relatively low content of PEO still retain good tensile properties and are, in principle, suitable for biomedical applications.