Modified Cellulose Nanofibers

Cellulose nanofibers (CNFs) [87, 88] and nanowhiskers (CNWs) [89] derived from renewable biomass have attracted much interest as alternatives to microsized and glass-fiber reinforcements in composite materials. Jonoobi et al. [87] developed CNF-reinforced polylactic acid (PLA) by twin-screw exfrusion. Obtained PLA/CNF nanocomposites with 5 wt% CNF showed improved tensile modulus and strength. Ljungberg et al. [89] prepared nanocomposite films of isotactic-PP reinforced with cellulose whiskers, which were highly dispersed in the PP matrix with a surfactant. The surfactant-modified whiskers acted as nucleating agents for isotactic-PP and the obtained nanocomposite displayed an increased tensile strength and strain at break as compared to the neat isotactic-PP. 

Jonoobi, M., Mathew, A. R, Abdi, M. M., Makinejad, M. D., Oksman, K. (2012). Aeomparison of modified and unmodified cellulose nanofiber reinforced polylactic acid (RLA) prepared by twin screw extrusion. (4), 991-997. 

C5 ras VP, Manfredi LB, Ton-That M-T, Vazquez A (2008) Physical and mechanical properties of thermoplastic starch/montmorillonite nanocomposite films. Carbohydr Polym 73 55-63 de Morals Teixeira E, Correa A, Manzoli A, de Lima Leite F, de Oliveira C, Mattoso L (2010) Cellulose nanofibers from white and naturally colored cotton fibers. Cellulose 17 595-606 de Moura MR, Aouada FA, Avena-Bustillos RJ, McHugh TH, Krochta JM, Mattoso LHC (2009) Improved barrier and mechanical properties of novel hydrox5q)ropyl methylcellulose edible films with chitosan/tripolyphosphate nanoparticles. J Food Eng 92 448—453 Dean K, Yu L, Wu DY (2007) Preparation and characterization of melt-extruded thermoplastic starch/clay nanocomposites. Compos Sci Technol 67 413 21 Duanmu J, Gamstedt EK, Rosling A (2007) Hygromechanical properties of composites of crosslinked allylglycidyl-ether modified starch reinforced by wood fibres. Compos Sci Technol 67 3090-3097... 

CeO nanoparticles were attached to the surface of the nanofiber substrate due to the strong interfacial and electrostatic interactions between the carboxylic or hydroxyl groups of the cellulose nanofiber and the CeO nanoparticles, which is effectively prevented nanoparticle fall-off. Compared to the natural cotton cellulose nanofibers, the modified natural cotton cellulose nanofibers by hydrothermal incorporation of CeOj nanoparticles showed excellent protection against UV radiation because of the function of the CeO particles. This functional nanofiber will have potential applications in various areas, such as the medical, military, biological, and optoelectronic industrial fields including UV protection for data storage or memory devices, in the future. 

Chahal, S., F. S. J. Hussain, and M. B. M. Yusoff, Characterization of Modified Cellulose (MC)/Poly (Vinyl Alcohol) Electrospun Nanofibers for Bone Tissue Engineering. Procedia Engineering, 2013,53,683-688. 

Stephen M, Catherine N, Brenda M, Andrew K, Leslie P, Corrine G (2011) Oxoltine-2,5-dione modified electrospun cellulose nanofibers for heavy metals adsorption. J Hazard Mater 192(2) 922-927. doi 10.1016/j.jhazmat.2011.06.001... 

The addition of water-soluble compounds affects the biosynthesis of cellulose chains (polymer formation), and they may also be adsorbed by single fibers as the nanofiber network is built (crystallization). Moreover, the bacterial cells themselves can be modified. 

Another modified spinneret was designed with multiple single jets in order to enhance nanofibers spinning rate of PEO (Theron et al. 2005) or to prepare nanofibrous mats composed of two different and immiscible polymers such as PVA and cellulose acetate. A multiple jet composed of four tips was used in order to blend PVA and cellulose acetate nanofibers in different ratios (Pham et al. 2006). In another study, a collector moving transversely was used in front of a multiple jet composed of two tips in order to produce a mixture of electrospun PEO and polyurethane (PU) nanofibers and a uniform distribution of this mixture was achieved due to the motion of the collector (Kidoaki et al. 2005). 

Strength). The nanosized particles most commonly used in PU foams are clearly silicate-layered nanoclays, and particularly unmodified or organically modified montmorillonite (MMT), though others have also been considered, such as carbon-based nanofillers (carbon nanotubes and nanofibers, and more recently graphene), nanosilica, or cellulose-based nanofillers. 

In the literature, hybrid solar cells with the active layer composed of CdS-coated cellulose acetate fibers and P3HT were reported by Cortina et al. [81]. Wu et al. reported the enhanced performance of hybrid solar cells made of ZnO nanoflbers by modifying the surface of fibers with CdS [82], To apply more electrospun nanofibers and QDs to hybrid solar cells, the generation of effective interface of electrospun metal oxide nanofibers with QDs before blending with polymer is necessary. Dispersion of QDs in electrospun fibers may be also an alternative way for hybrid applications. 

The results obtained by the authors were comparable to products produced from conventional cellulose paper [82]. Dahman and Oktem obtained an optically transparent nanostructured biocomposite composed of surface-modified BNC and poly(hydroxyethyl methacrylate). Composite samples containing 1% (w/w) nanofiber transmitted over 80% of the light, whereas samples with less than 1% (w/w) BNC content exhibited higher light transmittances [83]. Transparent NCC films open the doors to new applications for cellulose devices, e.g., paper displays, smart packaging, radiofrequency identification, and smart labels [82,83]. 

More than 100 polymers, both synthetic and natural, have been successfully electrospun into nanofibers, mostly from polyma solutions, as any polymer may be electrospun into nanofibers, provided that the polymer molecular weight is sufficiently high and the solvent can be evaporated in the time during the jet transit period, over a distance between the spinneret and the collector. Standard polymers successfully electrospun into nanofibers include polyacrylonitrile (PAN), poly(ethylene oxide) (PEO), poly(ethylene terephthalate) (PET), polystyrene (PS), poly(vinyl chloride) (PVC), Nylon 6, PVA, poly(8-caprolactone), Kevlar (poly[p-phenylene terephthalamide]), poly(vinylidene fluoride) (PVDF), polybenzimidazole, polyurethanes (PUs), polycarbonates, polysulfones, poly(vinyl phenol) (PVP), and many others [36,37]. Electrospinning has also been used to produce nanofibers from natural biomacromolecules, including cellulose [either electrospun from cellulose acetate (CA) with subsequent hydrolysis or directly electrospun from cellulose solutions in Af,Af-dimethylacetamide with lithium chloride], collagen and gelatin, modified chitin, chitosan, and DNA. 

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