Novel Polyvinyl Alcohol (PVA)/Cellulose Nanocrystal (CNC) Supramolecular Composite Hydrogels: Preparation and Application as Soil Conditioners

Abstract

In this work, cellulose nanocrystal (CNC) was modified by an ureido-pyrimidinone (UPy) system based on quadruple hydrogen bondings, and CNC-UPy was obtained. Then, this powder was added into polyvinyl alcohol (PVA), and PVA/CNC-UPy composite membranes and hydrogels were prepared. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), polarizing optical microscopy (POM) and particle size distribution (PSD) were used to characterize CNC-UPy. From the FTIR results, the characteristic peaks of NCO group sat 2270 cm−1 disappeared, indicating the successful synthesis of CNC-UPy. XRD results showed that the modification by UPy may change the structure of CNC and its degree of crystallinity was increased. PSD analysis showed that the particle size of CNC was increased and its size distribution became narrower after modification by UPy groups. The structure and properties of the composite membranes and hydrogels were studied by differential scanning calorimeter (DSC), thermogravimetric analysis (TGA) together with investigation of swelling, sustained release and self-healing performances. DSC curves depicted that the glass transition temperature, Tg, of different PVA membranes was increased with addition of different proportions of CNC-UPy. TGA data showed that the temperature of maximum weight loss rate was increased, which illustrated the enhanced thermal stability of PVA/CNC-UPy composites. Meanwhile, it was also revealed that the PVA/CNC-UPy composite hydrogels possess good self-healing and better sustained release behavior for the soil conditioner, fulvic acid (FA).

Cellulose Nanocrystals vs. Cellulose Nanofibers: A Comparative Study of Reinforcing Effects in UV-Cured Vegetable Oil Nanocomposites

“…All characteristic absorption bands of the nanocellulose were assigned from FTIR measurements shown in Figure S3 . The broad peak from approximately 3000 to 3650 cm −1 is related to –OH stretching vibrations [ 35 , 36 ]; the peak at 2900 cm −1 is assigned to the C–H stretching vibration [ 37 ]; the peak at 1430 cm −1 represents CH 2 symmetric bending [ 37 ], while the peak at 1316 cm −1 is assigned to CH 2 wagging, and C–OH in-plane bending at C6 can be observed at 1204 cm −1 [ 35 ]. The band at 1160 cm −1 corresponds to C–O–C asymmetric stretching at the β-glycosidic linkage [ 35 ].…”

“…The band at 1160 cm −1 corresponds to C–O–C asymmetric stretching at the β-glycosidic linkage [ 35 ]. Other characteristic absorption peaks of C–O in cellulose can be observed approximately at 1055 cm −1 [ 36 , 38 ] and at 1028 cm −1 , and C–O-specific C6 stretching is represented by the band at 985 cm −1 . The signature peak at 897 cm −1 is assigned to C–O–C asymmetric stretching at β-glycosidic linkages of amorphous cellulose [ 35 , 39 ].…”

Nanocellulose: Recent Fundamental Advances and Emerging Biological and Biomimicking Applications

“…[ 243 ] CNC was modified by an UPy and mixed with PVA to form hybrid self‐healing hydrogels. [ 244 ]…”

Ruthenium Decorated Polypyrrole Nanoparticles for Highly Sensitive Hydrogen Gas Sensors Using Component Ratio and Protonation Control

“…Therefore, to achieve advanced properties and performance, innovative materials are necessary for hydrogen sensor devices. In this respect, composite nanomaterials containing both organic and inorganic materials have been constantly studied and reported due to their excellent functionalities originating from each component [ 19 , 20 ]. As a sensor electrode material, the organic component (i.e., sp 2 carbon) acts as a charge transfer pathway and a template, whereas the inorganic component operates as binding site to target analyte.…”