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Poly(ionic) liquid (PIL) augmented membranes were fabricated through self-polymerization of 2-vinyl pyridine and 4-vinyl pyridine followed by dopamine triggered polymerization and bridging with inert polyamide support. The resulting membranes acquired a positive surface charge with a high degree of hydrophilicity. Fourier transformed Infra-red (FTIR) and Energy dispersive X-ray (EDX) spectroscopic investigation revealed the successful augmentation of PIL surface layer, whereas surface morphology was investigated through scanning electron microscopy (SEM) imaging. This manuscript demonstrates pi electron-induced separation of dyes with the trend in permeability: Coomassie Brilliant Blue G (CBBHG) > Remazol Brilliant Blue R (RBBR) > Eichrome Black T (EBT) > Congo Red (CR). CBBG exhibited extended conjugation over large aromatic domain. RBBR and EBT were associated withtheelectron-donating -NH₂ group and electron-withdrawing -NO₂ group, respectively, hence pi electron density on aromatic ring varied. The steric repulsion between two pairs of ortho hydrogens (Hs) in biphenyl moieties of CR resulted in deviation of planarity and hence aromaticity leading to the lowest permeability. The sugar fractionation followed the trend: Galactose > Mannose > Fructose > Glucose > Xylose. More hydroxyl (-OH) groups in sugars and their conformational alignment in the same direction, exhibited more lone pair of electrons leading to more interaction with PIL and hence better permeability. Pentose showed poorer permeation than hexose, whereas aldose showed better permeation than ketose. Full article

Aromatic polyamides or aramids are materials with exceptional thermal and mechanical properties. For this reason, they are considered high-performance materials with many applications in fields such as civil security (bullet-proof body armour or fire, chemical, and saw protection suits), transport (automotive and aerospace), and civil engineering, among many others. The remarkable properties arise from the high cohesive energy due to their chemical structure, including the rigidity of the main chain due to the wholly aromatic structure conjugated with the amide groups, the high average bond energy, and a strong and highly directional interchain hydrogen bonds between the amide moieties. Although the natural yellowish colour of the fibres is used, generally, most of the applications require coloured fibres. However, aramid fibres have poor dyeing properties for the same reasons that make them thermally and mechanically resistant, and traditional dyeing methods, such as dope dyeing, are inefficient and aggressive, which impairs the fibres’ properties. The ideal colour fastness of fibres is achieved by intrinsically, inherently, or self-coloured polymers by introducing a dye motif or chromophore monomer in the chemical structure of the polymer. In addition, the colour hue can be controlled by tuning the chromophore monomer molar content in the final composition. In previous research, we successfully obtained inherently blue-coloured aramids, with blue chromophore motifs unable to migrate and evenly distribute along the polymer chain and maintain their high-performance properties, and our aim now is to obtain red-coloured aramids prepared in the same fashion. Full article