Properties of quaternized and crosslinked carboxymethylcellulose films

The sodium salt of carboxymethylcellulose (CMC Na) is a suitable water-soluble derivative for the preparation of quaternized and crosslinked films. In this study, we prepared quaternized and crosslinked CMC Na (QCCMC) films, along with only quaternized (QCMC) and only crosslinked CMC Na (CCMC) derivatives, using one-step synthesis. The derivatives were characterized by high-resolution nuclear magnetic resonance (NMR) spectroscopy. Size-exclusion chromatographic multi-angle laser light scattering (SEC-MALS) revealed the solubilities of the studied derivatives: CMC Na (98.0%) > CCMC (81.2%) > QCMC (78.2%) > QCCMC (77.4%), while the gyration radii (R_g) of the polysaccharide coils were: CMC Na (20–78 nm) ≥ QCCMC (20–65 nm) ≥ QCMC (25–45 nm) ≥ CCMC (24–40 nm). Cyclic voltammetry distinguished all four types of derivatives with constant ΔE, I_a and I_c parameters. X-ray diffraction confirmed that all of the prepared films were in an amorphous state. PeakForce quantitative nanomechanical mapping (PF-QNM) was used to study the film surface morphology and film surface mechanical properties of all of the prepared carboxymethylcellulose derivatives. The following decreasing orders were found for root mean square surface films roughness: CCMC (6.5 nm) > CMC Na (6.4 nm) > QCMC (4.1 nm) > QCCMC (2.0 nm); films reduced elastic modulus: CCMC (9.3 GPa) > QCCMC (8.0 GPa) > CMC Na (7.0 GPa) > QCMC (2.1 GPa); films stiffness: CCMC (66.8 N/m) > CMC Na (55.4 N/m) > QCCMC (53.9 N/m) > QCMC (20.5 N/m) and films adhesion: CCMC (25.7 nN) > CMC Na (21.4 nN) > QCMC (17.1 nN) > QCCMC (11.5 nN).