Nanoparticles cellulose nanocrystals

Jimenez, A., Latterini, L., and Kenny, J. M. (2014). Nano-biocomposite films with modified cellulose nanocrystals and synthesized silver nanoparticles, 101,1122-1133. 

The cellulose based materials that are used as nano-reinforcements are cellulose nanocrystals (i.e. whiskers and nanospheres), nanofibrillated cellulose, regenerated cellulose nanoparticles and electrospun nanofibers. A wide range of polymer matrices have been used to form cellulose nanocomposites. Synthetic polymers such as polypropylene, poly(vinyl chloride) (PVC) [102], waterborne epoxy [103], waterborne polyurethane [104], polyurethane [105], poly-(styrene-co-butyl acrylate) [106], poly(oxyethylene) [107], polysiloxanes [108], polysulfonates [109], cellulose acetate butyrate [110,111], poly(caprolactone) [112], poly(viny 1 alcohol) [113] and poly (vinyl acetate) [114]. Different biopolymers such as starch-based... 

Stable aqueous suspensions of polysaccharide nanocrystals can be prepared by the acid hydrolysis of vegetable biomass. Different descriptors of the resulting colloidal suspended particles are used, including whiskers, mono-crystals and nanocrystals. The designation whiskers is used to describe elongated rod-like nanoparticles. These crystallites have also often been referred in the literature as microfibrils, microcrystals or microcrystallites, despite their nanoscale dimensions. Most of the studies reported in the literature refer to cellulose nanocrystals. A recent review described the properties and applications of cellulose whiskers in nanocomposites [31]. 

Enzyme hydrolysis and bleaching of sisal fibres was used for preparation of cellulose nanocrystals. The nanocrystals were dispersed in NR to form nanocomposites that exhibited increased modulus. Enzyme treatment provided nanoparticles that could be specifically prepared for varying thermomechanical properties. 

Different descriptors have been used in the literature to designate the crystalline rod-like nanoparticles. These particles are mainly referred to as whiskers, nanowhiskers, cellulose nanocrystals, NCC (nanocrystalline cellulose), monocrystals, microcrystals, or microcrystallites, despite their nanoscale dimensions. The terms microfibrils, microfibrillated cellulose (MFC), and nanofibrillated cellulose (NFC) are used to designate cellulosic nanoparticles obtained by a simple mechanical shearing disintegration process (Fig. 7.2) as described in the next section. 

Excluding the use of an aqueous polymer dispersion, or latex, an alternative way to process nonpolar polymer nanocomposites reinforced with cellulose nanocrystals consists of their dispersion in an adequate (with regard to matrix) organic medium. Coating with a surfactant or a surface chemical modification of the nanoparticles can be considered. The global objective is to reduce their surface energy in order to improve their dispersibUity/compatibility with nonpolar media. 

Bai W, Holbery J, Li K (2009) A technique for production of nanocrystalline cellulose with a narrow size distribution. Cellulose 16 455-465 Balasubramani M, Kumar TR, Babu M (2001) Skin substitutes a review. Bums 27 534—544 Barud HS, Barrios C, Regiani T et al (2008) Selfsupported silver nanoparticles containing bacterial cellulose membranes. Mater Sci Eng C-Biomim Supramol Syst 28 515-518 Battista OA (1950) Hydrolysis and crystallization of cellulose. Ind Eng Chem 42 502-507 Battista OA, Coppick S, Howsmon JA et al (1956) Level-off degree of polymerization. Relation to polyphase stracture of cellulose fibres. Ind Eng Chem 48 333-335 Beck-Candanedo S, Roman M, Gray DG (2005) Effect of reaction conditions on the properties and behavior of wood cellulose nanocrystal suspensions. Biomacromolecules 6 1048-1054... 

As a result of their diverse architecture, different descriptors such as whiskers, nanowhiskers, cellulose nanocrystals, nano-crystalline cellulose, monocrystals or microcrystallites are used in literature to describe crystalline rod-like nanoparticles (Eichhom et al, 2010 Frone et al, 2011 Khalil et al, 2012), while terms such as microfibrils, microfibrillated cellulose or nanofibrillated cellulose are used to describe cellulosic nanoparticles that are obtained as a result of mechanical shearing disintegration process (Siqueira et al, 2010 Siqueira et al, 2011). In this paper, sources, isolation, property and applications of natural cellulose fibers are reviewed. 

E. Fortunati, I. Armentano, Q. Zhou, A. lannoni, E. Saino, L. Visai, L.A. Berglimd, and J. Kenny, Multifunctional bionanocomposite films of poly (lactic acid), cellulose nanocrystals and silver nanoparticles, Carbohyd. Polym., 87,1596-605,2012. 

E. Fortunati, M. Peltzer, I. Armentano, A. Jimenez, and J.M. Kenny, Combined effects of cellulose nanocrystals and silver nanoparticles on the barrier and migration properties of PLA nano-biocomposites,/. FoodEng., 118,117-124, 2013. 

N. Rescignano, E. Fortunati, S. Montesano, C. Emiliani, J.M. Kenny, S. Martino, and I. Armentano, PVA bio-nanocomposites A new take-off using cellulose nanocrystals and PLGA nanoparticles, Carbohyd. Polym., 99,47-58, 2014. 

Yu, H.-Y., Yang, X.-Y., Lu, F.-F., Chen, G.-Y, and Yao, J.-M. Fabrication of multifunctional cellulose nanocrystals/poly(lactic acid) nanocomposites with silver nanoparticles by spraying method. Carbohydr. Polymer. 140 (2015) 209-219. 

Tensile strength Silver nanoparticles Bamboo nanocrystals Cellulose nanocrystals Cellulose nanofibers Cellulose nanowhiskers Chitosan... 

There are basically two families of nanosized cellulosic particles. The first one consists of cellulose nanocrystals and the second one is microfibrillated cellulose (MFC) [17]. However, different terminologies are used to describe these cellulose nanoparticles, leading to some misunderstanding and ambiguities. Currently, the isolation, characterization, and search for applications of novel forms of cellulose, variously termed crystallites, nanocrystals, whiskers, nanofibrils, and nanofibers, is generating... 

Figure 6.2 (A) Cetyltrimethyl ammonium bromide (CTAB) mediated synthesis of Ag nanoparticles on cellulose nanocrystals (B) Free standing clay nanopaper showing a large-area and translucent sample and inset (Scanning electron image of cryo-fractmed surface for hybrid MFC/montmorrillonite nanopaper) (C) FE-SEM micrograph of the cross-section of GNP-incorporated BC membrane and (D) FE-SEM image of freeze-dried pellicle of BC/D-ChNC nanocomposite synthesized in situ. Reprinted with permission from [60] and [117],...

The possibility to combine different reinforcement phases in a polymer matrix was also recently considered in order to obtain multifunctional systems with increased mechanical and thermal properties providing also an antimicrobial response. In a recently accepted paper [160] Fortunati et al. demonstrated the high potential benefits offered by nanotechnology in the development of tailor-made nanobiocomposites with specific applications by the combination of two different synthesized nanostructures inorganic nanoparticles and cellulose nanocrystals in a biodegradable polymer matrix. 

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