A multilevel factorial design of 2³ with 12 experiments was developed for the preparation of cellulose nanocrystals (CNC) from Agave tequilana Weber var. Azul bagasse, an agro-industrial waste from tequila production. The studied parameters were acid type (H₂SO₄ and HCl), acid concentration (60 and 65 wt% for H₂SO₄, 2 and 8N for HCl) temperature (40 and 60 °C for H₂SO₄, 50 and 90 °C for HCl), and hydrolysis time (40, 55 and 70 min for H₂SO₄; and 30, 115 and 200 min for HCl). The obtained CNC were physical and chemically characterized using dynamic light scattering (DLS), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XDR) techniques. The maximum CNC yield was 90 and 96% for HCL and H₂SO₄, respectively, and the crystallinity values ranged from 88–91%. The size and morphology of A. tequilana CNC strongly depends on the acid type and hydrolysis time. The shortest CNC obtained with H₂SO₄ (65 wt%, 40 °C, and 70 min) had a length of 137 ± 68 nm, width 33 ± 7 nm, and height 9.1 nm, whereas the shortest CNC obtained with HCl (2 N, 50 °C and 30 min) had a length of 216 ± 73 nm, width 69 ± 17 nm, and height 8.9 nm. In general, the obtained CNC had an ellipsoidal shape, whereas CNC prepared from H₂SO₄ were shorter and thinner than those obtained with HCl. The total sulfate group content of CNC obtained with H₂SO₄ increased with time, temperature, and acid concentration, exhibiting an exponential behavior of $C_{SG}=a{e}^{bt}$.

In this work, cellulose nanocrystals (CNCs) were obtained from the wood of Acacia farnesiana L. Willd (Huizache) via acid hydrolysis; then, they were used to reinforce polyacrylic acid–co-acrylamide (AAc/AAm) hydrogels synthesized in a solution process via in situ free radical photopolymerization. The nanomaterials were characterized using atomic force microscopy, dynamic light scattering (DLS), and the residual charge on the CNCs; the nanohydrogels were characterized using infrared spectroscopy, scanning electron microscopy, swelling kinetics, and Young’s modulus. Soluble-grade cellulose presented 94.6% α-cellulose, 0.5% β-cellulose, and 2.7% γ-cellulose, as well as a viscosity of 8.25 cp and a degree of polymerization (DP) of 706. The CNCs averaged 180 nm in length and 20 nm in width. In the nanohydrogels, it was observed that the swelling kinetic behavior followed the Schott kinetic model, at times lower than 500 h; after that, it became linear. The results show that the hydrogel swelling capacity depended on the crosslinking agent and CNC concentration, as well as the CNC chemical and morphological properties, rather than the CNC source. The hydrogels with CNCs exhibited a decreased swelling degree compared to the hydrogels without CNCs. Young’s modulus increased with CNC presence and depended on the concentration and characteristics of the CNC as a crosslinking agent.

In this work, cellulose nanocrystals (CNC) were obtained from the wood of Acacia far-nesiana L. Willd (huizache) by acid hydrolysis. These were used to reinforce polyacrylic acid-co-acrylamide (AAc/AAm) hydrogels synthesized in a solution process by in situ free radical photo-polymerization. The nanomaterials were characterized by atomic force microscopy and dynamic light scattering (DLS) and the residual charge on CNC; the nanohydrogels were characterized by infrared spectroscopy, scanning electron microscopy, swelling kinetics, and Young's modulus. The soluble grade cellulose presented 94.6% α-cellulose, 0.5% β-cellulose, and 2.7% γ-cellulose, a viscosity of 8.25 cp, and a degree of polymerization (DP) of 706. The CNC averaged 180 nm in length and 20 nm in width. In the nanohydrogels, it was observed that the Schott kinetic model was followed at times lower than 500 h; after that, the swelling kinetic behavior is linear. The re-sults show that the hydrogel swelling capacity depends on crosslinking agent and CNC concen-tration as the chemical and morphological CNC properties rather than a CNC source. The pres-ence of CNC decreases the swelling degree compared to hydrogels without CNC. Young's modu-lus increased with CNC presence and depended on CNC characteristics as crosslinking agent and concentration.