Synthesis of well‐defined poly(p‐benzamide) from chain‐growth polycondensation and its application to block copolymers

Abstract

Poly(p‐benzamide) with a defined molecular weight and a low polydispersity and block copolymers containing this well‐defined aramide was synthesized. Phenyl 4‐(4‐octyloxybenzylamino)benzoate (1b) polymerized at room temperature in the presence of base and phenyl 4‐nitrobenzoate (2a) as an initiator in a chain‐growth polycondensation manner to give well‐defined aromatic polyamides having the 4‐octyloxybenzyl groups as a protecting group on nitrogen in an amide. It was confirmed by a model reaction that deprotection of this protecting group proceeded completely with trifluoroacetic acid (TFA) without breaking the amide linkage. The utility of this approach to poly(p‐benzamide) with a low polydispersity was demonstrated by the synthesis of block copolymers of poly(p‐benzamide) and poly(N‐octyl‐p‐benzamide) or poly(ethylene glycol). The SEM images of the supramolecular assemblies of the former block copolymer showed μm‐sized bundles and aggregates of flake structures.

Soluble Oligoaramide Precursors—A Novel Class of Building Blocks for Rod–Coil Architectures

“…Ciferri et al have exploited the strong hydrogen bonding ability of poly(p-benzamide)s (PPBA) in block copolymers formed from PPBA and poly(ethylene glycol) (PEG). [20] Yokozawa et al developed a chain-growth polymerization route to PPBAs [21] and have reported triblock architectures with an outer PEG and an inner PPBA block. [22] Rod-coil block copolymers with well-defined, that is, monodisperse, OPBA as the rigid block have, to the best of our knowledge, not yet been reported.…”

Polycondensation of ‘a − bn’ or ‘a2 + + bn’ Monomers ‐ A Comparison

“…[48] Most of Yokozawa's work [45,47,50,53] was focused on the syntheses of aromatic polyamides. [54,58,[60][61][62]65,66] In numerous experiments phenyl N-alkyl-4-aminobenzoates were used as monomers. The N-substitution served two purposes.…”

“…[50] Diblock copolymers that consist of two differently substituted 4-amino benzoyl units (14 or 15) were prepared by means of phenyl 4-nitrobenzoate as initiator (Equation (45) and (46), Scheme 13). [47,54] Furthermore, star-shaped polyamides having three or four star arms were obtained, when the aromatic phenyl ester 16, 17 or 18 ( Figure 3) were used as electrophilic initiators. [60] Further experiments were conducted with the purpose to prepare homo-and copolyamides of N-substituted meta-aminobenzoic acids.…”

Chain‐growth polycondensation via the substituent effect: Investigation of the monomer structure on synthesis of poly(N‐octyl‐benzamide)

“…The CGC process, like other traditional living polymerization techniques, allows for the synthesis of block copolymers, and more recently, the synthesis of surface-initiated polymer brushes from polymers traditionally prepared using step-growth polymerization. [10,11] Aromatic polyamides are selected by industry for their impressive mechanical and thermal properties and notable chemical resistance. [12] Conventionally, the most famous aromatic polyamides, such as Kevlar © and Nomex © , are synthesized using a step-growth process where an aromatic diamine is reacted with a corresponding aromatic diacid chloride, producing very robust materials, due to the strength and stability of the aromatic backbones and the presence of hydrogen bonding.…”