One-pot Two-step Method Research Articles

Synthesis and Properties of Block Copolymers Based on Carboxyl-Terminated Polydimethylsiloxane and Aromatic Polyamides

Polysiloxane-aramid block copolymers were synthesized by a one-pot two-step method of direct polycondensation using triphenyl phosphite and pyridine as the condensing agents. Amine-terminated aramid oligomers were prepared by the reaction of 3,4′-oxydianiline and isophthalic acid, and subjected to polycondensation with α,ω-bis(10-carboxydecyl) olydimethylsiloxane to give block copolymers with inherent viscosities of 0.13—0.25 di g−1. They were soluble in amide-type solvents like N,N-dimethylacetamide and gave translucent and ductile films by casting from the solutions. These block copolymers start to decompose around 300°C. These properties are very similar to those of block copolymers derived from α,ω-bis(3-aminopropyl)polydimethylsiloxanes and carboxyl-terminated aramid oligomers.

Improved Synthesis of Polyether-Aramid Multi-Block Copolymers by Direct Polycondensation

Polyether-aramid multi-block copolymers having structural regularity were synthesized by a one-pot two-step method of direct polycondensation using triphenyl phosphite and pyridine as condensing agents. Amine-terminated telechelic aramid oligomers were prepared by the reaction of bis(4-aminophenyl) ether and isophthalic acid, and subsequently condensed with α,ω-poly(oxyethylene)dicarboxylic acid giving the multi-block copolymers with inherent viscosities of 0.5—0.7 dl g−1. No appreciable differences in thermal and tensile properties were observed between the multi-block copolymers thus prepared and those synthesized by the previously reported two-pot method. In contrast, the properties of these block copolymers differed significantly from those of a randomly coupled block copolymers prepared by the one-step procedure.

Synthesis and Properties of Multi-Block Copolymers Based on Polybutadiene and Aromatic Polyamides Having Unsymmetrical Structures

Polybutadiene-aramid multi-block copolymers having structural regularity were synthesized by a one-pot two-step method of direct polycondensation using triphenyl phosphite and pyridine as condensing agents. Amine-terminated telechelic aramid oligomers were prepared by the reaction of 3,4′-oxydianiline and isophthalic acid, and condensed with α,ω-polybutadienedicar-boxylic acid giving the multi-block copolymers with inherent viscosities of 0.2—0.4 dlg−1. They were soluble in a wide range of solvents including N,N-dimethylacetamide, pyridine, and tetrahydrofuran, and gave transparent, ductile, and elastomeric films by casting from the solutions of these solvents. Depression of the glass transition temperatures of polybutadiene phase in the multi-block copolymers was observed by increasing the aramid content. The tensile strength and modulus decreased with decreasing aramid content, whereas elongation at break increased.