Synthesis of a A2B3-type Hyperbranched Copolymers Based on a 3-Armed Unimolecular 4-N-Methylbenzamide Pentamer and Poly(propylene oxide)

Abstract

Abstract A novel hyperbranched copolymer (HBCP), with a number-average molecular weight from 11000 to 25000, was successfully prepared by the direct condensation polymerization of a unimolecular 3-armed 4-N-methylbenzamide pentamer (TMA-3MAB5) as a hard segment (B3 monomer), with amine-functionalized poly(propylene oxide) (PPOx) (x: degree of polymerization, 32 or 64) (A2 monomer) at both ends as a soft segment, and investigated its possibility as a thermoplastic elastomer. The highly pure B3 molecule, TMA-3MAB5, was quantitatively obtained by the step-growth reaction of 4-(N-methylamino)benzoic acid (MAB) using thionyl chloride as the condensation reagent and trimesic acid (TMA) as the core molecule in N-methylpyrrolidone (NMP) at 20 °C for 0.5 h for each step. The HBCP showed two glass transitions corresponding to imperfectly segregated PPO-rich and polybenzamide hard segment-rich domains, and the film showed good mechanical properties (Young’s Modulus TM 0.25–4.0 MPa, elongation at break EB 133–1470%), which were controlled by the fraction of the hard segment.