Rapid synthesis and properties of segmented block copolymers based on monodisperse aromatic poly(N-methyl benzamide) and poly(propylene oxide)†
Monodisperse aromatic N-methyl benzamide-based molecules (repeat number: x = 5–10, molar mass distribution Mw/Mn = 1.02–1.04) connected with terephthalic acid at both sides (MABx–x) were rapidly prepared by a step-wise condensation reaction using the reported one-pot dendrimer synthetic method. These were copolymerized with NH2-terminated poly(propylene oxide) (PPOy) using a condensation reagent at ambient temperature, and the relationship between the structure and the properties was evaluated. The copolymers, poly(MABx–x-b-PPOy), had Mn values up to 12 500 g mol−1 (Mw/Mn = 1.6), with only a single Tg at −70 °C by DSC, assignable to the pure PPO domain. Only for the copolymer films consisting of a monodisperse MABx–x segment, did the dynamic mechanical analysis (DMA) show two Tg values at −70 and above 50 °C, indicating the clear phase segregation of the copolymers. The mechanical properties of the copolymer films were mostly dependent on the fraction of the monodisperse hard segment, and the tensile modulus and elongation at break varied from 3.3 to 32.5 MPa and 150 to 540%, respectively.