Frustrated structures of polycaprolactam and poly(p-benzamide) in their rod–coil–rod triblock copolymers

摘要: Abstract A series of rod–coil–rod triblock copolymers were synthesized by two-step polycondensation with polycaprolactam (PA6) as the flexible block and poly( p -benzamide) (PBA) rod. Proton nuclear magnetic resonance ( 1 H NMR), UV–vis spectrophotometry differential scanning calorimetric (DSC) first performed to determine fundamental molecular structure thermal property each polymer. Through wide angle X-ray scattering (WAXS), Fourier transformation infrared spectroscopy (FT-IR) measurements, frustrated structures both components studied. For PA6, a quasi-γ mesomorphic order was found in transition-region nearby PBA domain which is more favored increase content owing stretching from rod different cross-section areas coil chains. On other hand, PA6 segments imposes constraint on blocks, leads reduction when volume fraction reaches approximately 45%. α crystals can form only copolymer low PBA, exhibit Brill transition feature during heating process though this ends prematurely melting crystals.