Synthesis and properties of multiblock copolymers based on polyoxyethylene and polyamides by diisocyanate method

Polyoxyethylene–polyamide multiblock copolymers were successfully synthesized from α, ω‐polyoxyethylene–dicarboxylic acid (POE–diacid), a mixture of two dicarbroxylic acids, and an aromatic discocynate by two synthetic routes, i.e., one‐step and two‐step method. In the two‐step method, α, ω‐diisocyanate‐terminated polyamide oligomers, preformed from a mixture of isophthalic acid (IPA) and azelaic acid (AZA) with 4,4′‐methylenedi (phenyl isocyanate) (MDI), were reacted with POE–diacid to form multiblock copolymers. In the one‐step method, the reaction components, MDI, IPA, AZA, and POE diacid, were reacted all together. These polymerizations were carried out in the presence of 3‐methyl‐1phenyl‐2‐phospholene 1‐oxide as a catalyst in tetramethylene sulfone, giving multiblock copolymers with inherent viscosities of 0.5–1.1 dL/g. They were soluble in amide‐type solvents, and transparent, ductile, and elastomeric films could be cast from their N,N‐dimethylacetamide solutions. The tensile strength and modulus of the films thus prepared decreased with an increase in the polyoxyethylene content, whereas the elongation at break increased. The tensile strength/elongation at break/tensile modulus of the multiblock copolymer films ranged from 47 MPa/160%/1.1 GPa to 15 MPa/880%/12 MPa.