Bis-TEGylated Poly(p-benzamide)s: Combining Organosolubility with Shape Persistence

Abstract

The synthesis of perfectly planar, bis-substituted aromatic polyamides is reported herein. With highly flexible triethylene glycol chains attached and conformational restriction through intramolecular, bifurcated hydrogen bonds these are among the most shape-persistent yet organo-soluble polymers to date. Starting from 4-nitrosalicylic acid, our group developed a route to phenyl-2,5-bis-TEGylated aminobenzoate, which could be polymerized by addition of lithium bis(trimethylsilyl)amide (LiHMDS). Since this technique has not been applied to step-growth polycondensations of polyaramides so far, the influence of two different solvents and an N-protective group was investigated. Therefore, substituted phenyl aminobenzoate derivatives carrying a free amine or an N-protective group have been polymerized. Additionally, the tendency for self-assembly of the readily soluble bis-TEGylated poly(p-benzamide) was observed by transmission electron microscopy (TEM) in the dried state. Dynamic light scattering (DLS) measurements of chloroform solutions did not indicate the formation of aggregates. Thus, intermolecular interactions, which other aromatic polyamides typically exhibit, are prevented. The access to bis-substituted, entirely rigid poly(p-benzamide)s via this new polycondensation method paves the way for exciting new structures in materials science and supramolecular chemistry.

Chain‐growth condensation polymerization approach to synthesis of well‐defined polybenzoxazole: Importance of higher reactivity of 3‐amino‐4‐hydroxybenzoic acid ester compared to 4‐amino‐3‐hydroxybenzoic acid ester

“…Consequently, it turned out that CGCP of 1b did not occur, even though the monomer conversion reached 100% in the polymerization with KHDMS at 50 °C. A similar reduction of reactivity of 4‐amino benzoate monomer having 3‐oligo(oxyethylene) side chain was observed in the condensation polymerization of phenyl 2,5‐bis‐TEGylated (4‐methoxybenzylamino)benzoate …”

Synthesis of well‐defined, soluble poly(3‐alkyl‐4‐benzamide) by chain‐growth condensation polymerization

“…Another approach to improve the solubility is the attachment of flexible side chains to the aramide backbone . In recent years, Kilbinger introduced dendrons and a hexyloxy side chain at the 2 position of poly(4‐benzamide), and tri(ethylene glycol) monomethyl ether (TEG) side chains at the 2 and both the 2 and 5 positions . The solubility of these polyamides is sensitive to side chain structure.…”

“…The hexyloxy‐substituted polyamide was insoluble in organic solvents. The solubility of 2‐TEG polyamide is dependent on the polymerization method; probably low‐molecular‐weight polyamide exhibits good solubility while high‐molecular‐weight polymer is insoluble in organic solvents such as tetrahydrofuran (THF), dichloromethane, and N,N ‐dimethylformamide (DMF) . The polyamide with 2,5‐bisTEG side chains showed good solubility, despite its high molecular weight.…”

Synthesis and properties of poly(norbornene)s with lateral aramid groups

“…4 One possibility to overcome this disadvantage is the attachment to soluble polymer chains. 5,6 To date, research within the field of comb polymers focused mostly on rod-like polymers with hairy side chains 7,8 or on rigid rod-like side chains connected via a flexible linker to the main chain. 9 Only few reports exist on theoretical studies 10 and syntheses 11 of polymers in which the rod-like side chain is directly bound to the main chain.…”