One-pot eco-friendly oxidative synthesis of imine carboxymethyl dialdehyde cellulosic fibers

The quest to efficiently produce renewable and sustainable functional cellulosic products has prompted the development of an environmentally sensitive and cost-effective method to produce multi-functionalized cellulose fibers, which can further be molded or spun to functional products. Here we report on imine carboxymethyl dialdehyde modified cellulose fibers (ICDAMF). Its synthesis is achieved by optimizing a sequential one-pot consisting of (i) partial modification of Kraft cellulose pulp using carboxymethylation (0.92 ± 0.21 mmol/g), (ii) periodate oxidation (3.0 ± 0.4 mmol/g) and (iii) Schiff base (~ 0.1 mmol/g) reactions. Multi-functionalization allows integration of desirable functional groups, in this case, carboxyl groups (0.9 ± 0.2 mmol/g) for gel formation and aldehyde groups (3.0 ± 0.4 mmol/g) for covalent adsorption of diamine dyes. Periodate oxidation stereospecifically cleaves the C2–C3 bonds of glucose units to form aldehydes, locally disturbing the crystalline structure which leads to high temperature solubility. Diamine dyes can act as crosslinkers thereby reducing fiber disintegration and high temperature solubility. ICDAMF has potential use in textiles, via waste-free covalent addition of dyes, critical in preventing leaching of dyes which can cause serious environmental pollution. The reaction progress was monitored by conductometric titrations and UV–visible spectroscopy. Product characterization was done by Fourier transform infrared, nuclear magnetic resonance, UV–visible and X-ray diffraction spectroscopies.