Naturally derived cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are emerging nanomaterials that display high strength, high surface area, and tunable surface chemistry, allowing for controlled interactions with polymers, nanoparticles, small molecules, and biological materials. Industrial production of nanocelluloses is increasing rapidly with several companies already producing on the tons-per-day scale, intensifying the quest for viable products across many sectors. While the hydrophilicity of the nanocellulose interface has posed a challenge to the use of CNCs and CNFs as reinforcing agents in conventional plastics, it is a significant benefit for creating reinforced or structured hydrogel composites (or, when dried, aerogels) exhibiting both mechanical reinforcement and a host of other desirable properties. In this context, this Review describes the quickly growing field of hydrogels and aerogels incorporating nanocelluloses; over 200 references are summarized in comprehensive tables ...

http://pubs.acs.org/doi/pdf/10.1021/acs.chemmater.7b00531

Review of Hydrogels and Aerogels Containing Nanocellulose

Cellulose nanocrystals and cellulose nanofibrils based hydrogels for biomedical applications.

The current application of nanotechnology in food and agriculture.

The fibrillation of pulp fiber was attempted by two methods, a high-pressure homogenizer treatment and a grinder treatment. The grinder treatment resulted in the successful fibrillation of wood pulp fibers into nanofibers. The nanofibers demonstrate promising characteristics as reinforcement material for optically transparent composites. Due to the size effect, the nanofiber-reinforced composite retains the transparency of the matrix resin even at high fiber content such as 70 wt %. Since the nanofiber is an aggregate of semi-crystalline extended cellulose chains, its addition also contributes to a significant improvement in the thermal expansion properties of plastics while maintaining its ease of bending. Cellulose nanofibers have tremendous potential as a future resource since they are produced in a sustainable manner by plants, one of the most abundant organic resources on earth.

Optically transparent composites reinforced with plant fiber-based nanofibers(ABSTRACTS (MASTER THESIS FOR GRADUATE SCHOOL OF AGRICULTURE))

Adhesion and Adhesives Edited by Dr. R. Houwink and Dr. G. Salomon. Vol. 1: Adhesives. Second, completely revised edition. Pp. xvi + 548. (Amsterdam, London and New York: Elsevier Publishing Company, 1965.) 135s.

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Adhesion and Adhesives

Over the past few years, nanocellulose (NC), cellulose in the form of nanostructures, has been proved to be one of the most prominent green materials of modern times. NC materials have gained growing interests owing to their attractive and excellent characteristics such as abundance, high aspect ratio, better mechanical properties, renewability, and biocompatibility. The abundant hydroxyl functional groups allow a wide range of functionalizations via chemical reactions, leading to developing various materials with tunable features. In this review, recent advances in the preparation, modification, and emerging application of nanocellulose, especially cellulose nanocrystals (CNCs), are described and discussed based on the analysis of the latest investigations (particularly for the reports of the past 3 years). We start with a concise background of cellulose, its structural organization as well as the nomenclature of cellulose nanomaterials for beginners in this field. Then, different experimental procedures for the production of nanocelluloses, their properties, and functionalization approaches were elaborated. Furthermore, a number of recent and emerging uses of nanocellulose in nanocomposites, Pickering emulsifiers, wood adhesives, wastewater treatment, as well as in new evolving biomedical applications are presented. Finally, the challenges and opportunities of NC-based emerging materials are discussed.

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Nanocellulose: From Fundamentals to Advanced Applications

Cellulose microfibrils (CMFs) and cellulose nanofibrils (CNFs) were isolated from hardwood pulp by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation, which produced negatively-charged carboxylate groups on their surface. First, these CMFs and CNFs were used to prepare microgels and nanogels, respectively, at different concentrations of cellulose and trivalent Al3+ cation by inducing ionic interactions between the negatively charged carboxylates and the metal cation. Then, two other cations (i.e., divalent Ca2+ and monovalent H+ were employed to understand the structure–property relationship these hydrogels. We characterized their morphology, chemical groups, mechanical properties, surface area, and pore size, and evaluated their drug-release behaviors using theophylline. Compared to the hydrogels prepared from divalent or monovalent cations, both microgel and nanogel prepared from trivalent Al3+ showed the highest stiffness and compressive strength, which indicated that they possessed the strongest ionic cross-linking via intra- and inter-fibrillar interactions. With a decrease in the valency of the cation used, the surface area of both hydrogels decreased, while their pore radius and calculated fibril diameter increased, indicating that a higher valency cation produced a hydrogel with higher porosity and a tighter network structure. The nanogel prepared from Al3+ also showed the highest swelling ratio and the lowest release of theophylline, while that of microgel was, in contrast, consistent. The low total drug-release behavior in nanogels was attributed to their compact and highly porous structure. The Higuchi model was the best-fit model of drug release kinetics. These results indicate that the characteristics and internal structure of hydrogel has a great impact on its properties and drug-release profile, and that it may be possible to finely tune hydrogel properties and drug release profile by altering the internal structure of hydrogels during its preparation.

Characteristics of TEMPO-oxidized cellulose fibril-based hydrogels induced by cationic ions and their properties

Dual responsive composite hydrogels were successfully prepared by combining cellulose nanofibril (CNF) isolated by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation with thermally responsive poly(N-isopropylacrylamide) (PNIPAAm) for drug release at 10 wt% CNF loading and − 20 °C polymerization temperature. pH responsive hydrogels were acquired by adjusting the carboxyl charge level of the CNF during TEMPO-mediated oxidation. CNF–PNIPAAm hydrogels fabricated were characterized in regards to compressive strength, functional group, low critical solution temperature (LCST), and swelling ratio of the hydrogels at different temperatures from 20 to 60 °C and pH levels from 2 to 10. Finally, the drug release behavior of these hydrogels was also investigated using methylene blue as a model drug. As the carboxylate content increases, the dual responsiveness of hydrogel improved at the expense of the compression strength. The CNF–PNIPAAm hydrogels were swollen and translucent below the LCST, and shrunken and opaque above the LCST. The Higuchi and the Krosmeyer and Peppas model was best-fitted to the drug release behavior of these hydrogels at pH 10 and pH 2, respectively. The results also indicated that a proper selection of polymerization temperature provided a way of tuning the dual-responsiveness of the hydrogels. These results also suggest that the CNF–PNIPAAm hydrogels can release drugs on demand.

Dual-responsive composite hydrogels based on TEMPO-oxidized cellulose nanofibril and poly(N-isopropylacrylamide) for model drug release

Influence of sonication treatment on supramolecular cellulose microfibril-based hydrogels induced by ionic interaction

Using oil palm trunk (OPT) layered with empty fruit bunch (EFB), so-called hybrid plywood enhanced with palm oil ash nanoparticles, with phenol-formaldehyde (PF) resin as a binder, was produced in this study. The phenol-formaldehyde (PF) resins filled with different loading of oil palm ash (OPA) nanoparticles were prepared and used as glue for layers of the oil palm trunk (OPT) veneer and empty fruit bunch fibre mat. The resulting hybrid plywood produced was characterised. The physical, mechanical, thermal, and morphological properties of the hybrid plywood panels were investigated. The results obtained showed that the presence of OPA nanoparticles significantly affected the physical, mechanical, and thermal properties of the plywood panels. Significant improvements in dimension from water absorption and thickness swelling experiments were obtained for the plywood panels with the highest OPA nanoparticles loading in PF resin. The mechanical properties indicated that plywood composites showed improvement in flexural, shear, and impact properties until a certain loading of OPA nanoparticles in PF resin. Fracture surface morphology also showed the effectiveness of OPA nanoparticles in the reduction of layer breakage due to force and stress distribution. The thermal stability performance showed that PF filled OPA nanoparticles contributed to the thermal stability of the plywood panels. Therefore, the results obtained in this study showed that OPA nanoparticles certainly improved the characteristic of the hybrid plywood.

https://www.mdpi.com/2073-4360/12/5/1007/pdf

Nanang Masruchin

Papers

Nanocellulose: From Fundamentals to Advanced Applications

Characteristics of TEMPO-oxidized cellulose fibril-based hydrogels induced by cationic ions and their properties

Dual-responsive composite hydrogels based on TEMPO-oxidized cellulose nanofibril and poly(N-isopropylacrylamide) for model drug release

Influence of sonication treatment on supramolecular cellulose microfibril-based hydrogels induced by ionic interaction

Enhancement of Oil Palm Waste Nanoparticles on the Properties and Characterization of Hybrid Plywood Biocomposites.