Nematogenic Block Copolymers of Rigid and Flexible Aromatic Units. I. Synthesis and Characterization

摘要

The phosphorylation reaction of Yamazaki and Higashi was used to prepare wholly aromatic block copolymers containing the rigid units poly(p-benzamide) (PBA) or poly(p-phenylene terephtalamide) (PPD-T) and the flexible units poly(m-phenylene isophthalamide) (MPD-I) or the polyterephthalamide of p-aminobenzhydrazide (PPD-T). Three synthetic procedures were investigated: A) monomers of the flexible block were added to the rigid prepolymer, B) monomers of the flexible block were added to the carboxy terminated rigid prepolymer, and C) the reaction of the carboxy terminated prepolymer of the rigid block with amine terminated prepolymer of the flexible block. Extraction of the copolymer with a non-solvent for the rigid homopolymer indicates that method B) gives the smallest amount of the flexible homopolymer. The extract from the PBA/MPD-I block copolymer was shown to be the flexible MPD-I homopolymer by NMR. The extract from the PBA/PABH-T copolymer could not be characterized by NMR due to overlapping of the spectra, but differential scanning calorimetry was used to identify the extract as PABH-T.