Synthesis, characterization, and properties of semifluorinated organo‐soluble new aromatic polyamides

Abstract

A series of organo‐soluble new polyamides were synthesized by the direct polycondensation of different semifluorinated aromatic diamines, namely 4,4‐bis[3'‐trifluoromethyl‐4'(4“‐amino benzoxy)benzyl]biphenyl; 4,4”‐bis(aminophenoxy)‐3'3“‐trifluoromethyl terphenyl; 1,3‐bis[3'‐trifluoromethyl‐4'(4”‐amino benzoxy)benzyl]benzene; 2,6‐bis(3'‐trifluoromethyl‐p‐aminobiphenyl ether)pyridine; and 2,5‐bis(3'‐trifluoromethyl‐p‐aminobiphenyl ether)thiophene with 5‐t‐butyl‐isophthalic acid. The polymers were fully characterized by elemental analysis and IR, NMR spectroscopies. The synthesized polyamides were soluble in several organic solvents such as 1‐methyl‐2‐pyrrolidone, N,N‐dimethylformamide, N,N‐dimethylacetamide, tetrahydrofuran, and dimethyl sulfoxide at room temperature. They showed inherent viscosities of 0.42–0.63 dl/g. The polyamides exhibited weight‐average molecular weights of up to 233,000, which depended on the exact repeating unit structure. The polyamides synthesized from 4,4‐bis[3'‐trifluoromethyl‐4'(4”‐amino benzoxy)benzyl]biphenyl and 5‐t‐butyl isophthalic acid exhibited highest glass‐transition temperatures 261°C (evaluated by differential scanning calorimetry) in nitrogen. These polyamides showed good thermal stability up to 475°C for a 10% weight loss in air. The polyamides films were clear and flexible in nature with tensile strengths of up to 88 MPa, modulus of elasticity of up to 1.81 GPa, and elongations at break of up to 25%, which depended on the exact repeating unit structure. X‐ray diffraction measurements indicated that these polyamides were amorphous in nature. Copyright © 2010 John Wiley & Sons, Ltd.

Solution‐processable and electroactive aromatic polyamides with 3,5‐bis(trifluoromethyl)triphenylamine moiety

“…One of the common approaches for increasing solubility and processability of aramids without much sacrificing their high thermal stability is the introduction of bulky, packing‐disruptive groups into the polymer backbone . Introduction of trifluoromethyl (CF 3 ) groups into aramids has been one of the most widely used strategies for structural modification leading to substantial solubility enhancement . It has also been demonstrated that aramids containing three‐dimensional, propeller‐shaped triphenylamine (TPA) unit are amorphous, have good solubility in organic solvents and good film‐forming capability, and exhibit high thermal stability .…”

Influence of moieties on morphology, thermal, and dielectric properties in polyamide‐polyhedral oligomeric silsequioxanes nanocomposites

“…CFPA‐POSS had a lower dielectric constant than that of the other polyamides because of the presence of hexafluoroisopropylidene group. Such type of results could be ascribed the increase in the free volume reduction in chain–chain interaction in fluorinated nanocomposites [23,24]. It was observed that the polyamides containing bulky POSS and fluoro groups could effectively decrease dielectric constants of the polyamides.…”

Fluorinated Polyamides

“…All these PAs (Figure 4.7) showed good thermal stability (T d,10% = 409-475 °C) under air. It was observed that the polymer (PA A-xiii) containing quadriphenyl moiety showed higher tensile strength and higher elongation at break compared to the polymer containing terphenyl moieties (PA A-xi) [47,48]. The PA A-xiii exhibited the highest T g value (261 °C) in the series, which could be explained on the basis of the presence of a rigid quadriphenyl unit in the polymer backbone.…”

“…The effect of the heterocyclic moiety and the catenation angle on the poly(ether amide)s was also investigated [47]. It was observed that with the decrease in the catenation angle, the solubility of the polymers increased due to the inhibition in polymer chain packing.…”

“…Aromatic glassy polymers having high T g s, e.g., PAs, polysulfone, polycarbonates, poly(arylene ether)s, and poly(ether ketone)s, exhibit both high gas permeability and selectivity and are considered as materials for membrane-based gas separation [1,[3][4][5]8,24,25,[45][46][47][57][58][59][60][61][62][63]. However, aromatic PAs have been identified as efficient barrier materials and showed somewhat high permselectivity for different gas pairs [1].…”