Cotton cationization with low molecular weight or polymeric cationic modifiers allows the effective dyeing of cotton substrates with reactive dyes under salt-free and more environmentally friendly conditions. The current work focuses on the spectroscopic study of the intermolecular interactions, which dictate the physicochemical process associated with fabric dyeing. Water-soluble cationic copolymers of vinyl benzyl chloride (VBC) and vinyl benzyl triethylammonium chloride (VBCTEAM) have been used as cellulose cationic modifiers. Dye uptake was assessed using Remazol Brilliant Blue R and Novacron Ruby S-3B dyes. The study involves ATR-FTIR, UV-Vis, fluorescence, and XPS spectroscopy. The results of binary polymer-rich dye-polymer aqueous solutions or dye-polymer precipitates at stoichiometric charge-ratio revealed that the sulfonate/sulfate anions of the dyes interact with the cationic VBCTEAM units of the polymer via electrostatic interactions. Moreover, the comparative study of dye application on modified and unmodified fabrics suggests that, unlike the latter, where dyes are chemically bound to cellulose, electrostatic forces dominate the interaction of modified fabrics with dye molecules.

Bio-nanocomposites based on poly (vinyl alcohol) (PVA) and cellulosic nanostructures are favorable for active food packaging applications. The current study systematically investigates the mechanical properties, gas permeation, and swelling parameters of PVA composites with cellulose nanocrystals (CNC) or nano lignocellulose (NLC) fibers. Alterations in these macroscopic properties, which are critical for food packaging applications, are correlated with structural information at the molecular level. Strong interactions between the fillers and polymer host matrix were observed, while the PVA crystallinity exhibited a maximum at ~1% loading. Finally, the orientation of the PVA nanocrystals in the uniaxially stretched samples was found to depend non-monotonically on the CNC loading and draw ratio. Concerning the macroscopic properties of the composites, the swelling properties were reduced for the D1 food simulant, while for water, a considerable decrease was observed only when high NLC loadings were involved. Furthermore, although the water vapor transmission rates are roughly similar for all samples, the CO₂, N₂, and O₂ gas permeabilities are low, exhibiting further decrease in the 1% and 1–5% loading for CNC and NLC composites, respectively. The mechanical properties were considerably altered as a consequence of the good dispersion of the filler, increased crystallinity of the polymer matrix, and morphology of the filler. Thus, up to ~50%/~170% enhancement of the Young’s modulus and up to ~20%/~50% enhancement of the tensile strength are observed for the CNC/NLC composites. Interestingly, the elongation at break is also increased by ~20% for CNC composites, while it is reduced by ~40% for the NLC composites, signifying the favorable/unfavorable interactions of cellulose/lignin with the matrix.

The modification of cotton fabrics with water-soluble cationic copolymers for salt-free dyeing applications with reactive dyes is explored in the present work. To this end, a family of bifunctional water-soluble cationic copolymers was designed through the chemical modification of poly(4-vinyl benzyl chloride), PVBC, with triethylamine, TEAM. These copolymers were applied onto cotton fabrics in aqueous alkaline solutions at moderate temperature (60 °C). The successful cotton modification was verified through the characterization of the modified samples with Raman and XPS spectroscopy. Moreover, a polymer coverage of the fabric of the order of 0.1% (w/w) was estimated following the polymer exhaustion through UV–Vis spectroscopy of the aqueous solutions used for the modification. The modification kinetics were followed through the evolution of the Raman spectra of the modified fabrics, the polymer exhaustion of the aqueous modification solutions and, indirectly, the dye exhaustion of the dyebaths using a reactive dye, namely Novacron Ruby S-3B. All techniques claim that fabric modification is practically accomplished within the first 1–2 h. The double functionality of the copolymers was explored through the XPS study of the modified fabrics, revealing that both electrostatic binding and covalent bonding of the cationic copolymers with the anionic surface of the fabric are expected to take place. As an important consequence, the polymer-modified fabrics are strongly dyed under eco-friendlier conditions, namely in salt-free alkaline solutions at room temperature, in contrast to the barely dyed unmodified fabric. Graphical abstract

The impact of titanium dioxide (TiO₂) on the physical properties of poly(lactic acid) (PLA) is explored, along with the combined effect of Atomic Layer Deposition of zinc oxide (ZnO) on the nanocomposite films' surface. PLA/TiO₂ bionanocomposites are prepared via melt‐extrusion and characterized in terms of their morphological, thermal, and mechanical properties. Homogeneous dispersion of the filler offers enhanced mechanical performance for samples up to 5 wt% in TiO₂ content. Thermal stability of PLA is also slightly improved upon increasing TiO₂ content. This work also demonstrates that surface modification of PLA/TiO₂ films employing Atomic Layer Deposition of zinc oxide enhances hydrophobicity, while antimicrobial activity, although mild, appears enhanced for coated samples. Water vapor permeability is retained in both coated and uncoated nanocomposites. Surface characterization of the studied specimens, by x‐ray photoelectron spectroscopy and scanning electron microscopy, reveals subsurface diffusion and reaction of the depositing compounds within PLA, leading to a different surface chemistry involving Zn(OH)₂. This study gives valuable insights on the parameters affecting the atomic layer deposition of inorganic coatings on a polymeric substrate in the presence of nanoinclusions and, therefore, on the physical properties of the coated films, providing the pathway for their exploitation in food packaging applications.

Cotton cationization with low molecular-weight/polymeric cationic modifiers allows the effective dyeing of fabrics with reactive dyes under salt-free and more environmentally-friendly conditions. The current work focuses on the spectroscopic study of the intermolecular interactions, which dictate the physicochemical process associated with dyeing. Water-soluble copolymers of vinyl benzyl chloride and vinyl benzyl triethylammonium chloride (VBCTEAM) have been used as cellulose cationic modifiers. Dye uptake was assessed using Remazol Brilliant Blue and Novacron Ruby dyes. The study involves ATR-FTIR, UV-Vis, fluorescence and XPS spectroscopy. The results of binary polymer-rich dye-polymer aqueous solutions or dye-polymer precipitates at stoichiometric charge-ratio revealed that the sulfonate/sulfate anions of the dyes interact with the cationic VBCTEAM units of the polymer via electrostatic interactions. Moreover, the comparative study of unmodified/modified dyed cotton indicates that the dye reactive sites remain unaffected for cationized cotton, suggesting that electrostatic interactions are the main driving force for the high dyeing performance observed.