Semi-Aromatic Polyether Amide Thermoplastic Elastomer: Nucleophilic Substitution Polymerization and Properties

Different from the traditional electrophilic polymerization method of thermoplastic elastomer, here, we adopted a new nucleophilic reaction route, which did not need extreme high temperature and vacuum condition to prepare a novel kind of semi-aromatic thermoplastic polyether amide elastomers. First, difluoro-terminated semi-aromatic di-amide monomer containing long chain ether (or 1,12-diaminododecane) was synthesized through facile interfacial electrophilic substitution reaction. Then, they were conducted to react with hydroquinone under atmospheric pressure to yield polyether amide elastomer. Additionally, a small amount of branched structure with trifluoro-terminated semi-aromatic amide monomer was designed and further introduced into the polymer chain to adjust the mechanical property. These semi-aromatic polyamide elastomers were found to have excellent thermal properties with glass transition temperature (Tg) of −39.5 to −34.8 °C, melting temperature (Tm) of 227.3–260.4 °C [which is much higher than that of the commercial products such as Pebax5533 (Arkema, Paris, France) (Tm = 159 °C)], the 5% weight-loss temperature (Td,5%) of 376.3–408.7 °C, and Vicat softening temperature of 73.0–223.6 °C. The mechanical properties of these resultant elastomers were good and can be controlled with different copolymerization ratios of soft, hard, and branched segments. The tensile strength, elongation at break, and elasticity modulus were in the range of 9.8–23.4 MPa, 87.6–712.3%, and 30.8–362.0 MPa, respectively. Besides, such a series of copolymers showed a relatively low water absorption of 1.57–3.67%. Interestingly, it was found that these resultant polyether amide elastomers had better organic solvent resistance and acid–base corrosion than the traditional TPAE-containing ester bond (−COO−) in the polymer molecular chain. It can be potentially applied in the chemical mechanical seal, especially in the high temperature and corrosion environment.