A Study on the N-Allylation Reaction of Aromatic Polyamides. 1. Poly(p-phenylene terephthalamide)

Abstract

Aromatic polyamides represent an important class of polymeric materials from both the academic and the industrial points of view. Unfortunately, because of strong intermolecular interactions mainly due to hydrogen bonding, their solubility in common organic solvents is often extremely poor. In most cases, this drawback does not allow aramide molecular characterization. In the present work, the above difficulties have been overcome by a functionalization reaction leading to N-allyl derivatives of the parent aramide, that are easily soluble in organic solvents. Poly(p-phenylene terephthalamide) has been chosen as the reference aramide to be functionalized, on the basis of its industrial relevance as well as its insolubility in all organic media. Molar mass distribution of its N-allylated derivative has been obtained by SEC, using chloroform + 0.3% acetic acid as mobile phase, thus allowing full molecular characterization of the parent polymer.

Synthesis, characterization and properties of a hyperbranched aromatic polyamide: poly(ABZAIA)

“…18%, i. e. it is relatively small and does not appear linked to HB molecular weight, at variance with other systems. [23] As expected, the polydispersity index D = M -w /M -n , evaluated by MALS, has been found substantially lower than the corresponding value obtained from SCV. Indeed, it is well known that MALS detector tends to underestimate the polydispersity, because of its poor sensitivity to low molecular weight fractions.…”

“…Indeed, it is well known that MALS detector tends to underestimate the polydispersity, because of its poor sensitivity to low molecular weight fractions. [23] Therefore, it is reasonable to consider the D ratios evaluated from the second configuration only, which provides values from ca. 2.7 to ca.…”

“…SEC measurements were carried out on a multi-detector SEC system, based on a Waters Alliance 2690 separation module equipped with a differential refractometer, a single capillary viscometer (SCV) and a multi-angle laser light scattering detector (MALS). Characteristics and performances of the multidetector SEC-MALS-SCV system have been described elsewhere, [23] including references quoted therein. A column set based on four styragel columns from Waters (HR5, HR4, HR3 and HR0.5; 36 000 theoretical plates) was used at 50 8C, with DMF + 0.5 M LiCl as mobile phase (flow rate: 0.7 mL N min -1 ; injection volume: 300 lL).…”

Structures and properties of polyimide fibers containing ether units

“…To overcome the drawback, some modifications should be done in attempt to improve the mechanical properties. Generally, the introduction of specific groups into the polymer backbone has been considered as a typical approach to modify the chemical structure of PI fibers, as outstanding properties of individual group could be integrated to form new high-performance polymers [19,20]. So far, in order to improve mechanical properties of PI fibers, the monomers contain rigid aromatic heterocyclic units, such as 2-(4-aminophenyl)-6-amino-4(3H)-quinazolinone (AAQ), 2,5-bis(4-aminophenyl)-pyrimidine (2,5PRM), and 2-(4-aminophenyl)-5-aminobenzimidazole (BIA), are preferred to increase the rigidity of the polymer chain and introduce additional intermolecular associations [10,21,22].…”

Preparation and characterization of novel polyimide films containing amide groups

“…What's more, hydrogen bond, as the strongest physical interaction, is a useful way to improve the mechanical properties [7][8][9][10].…”