Cellulose nanoparticles

In the transmission electron microscopy (TEM) images, the starch nanoplatelets (SNPs) are believed to aggregate as a result of hydrogen bond interactions due to the surface hydroxyl groups [13] (Fig. lA). Blocking these interactions by relatively large molecular weight molecules obviously improves the individualization of the nanoparticles. The acetylated starch and cellulose nanoparticles (SAcNPs and CelAcNPs) appeared more individualized and monodispersed than their unmodified counterparts with a size of about 50 nm (Fig. IB C). 

S. Kohler, T. Liebert, and T. Heinze, Interaction of ionic liquids with polysaccharides. VI. pure cellulose nanoparticles from trimethylsilyl cellulose synthesized in ionic liquids, J. Polym. Set A Polym. Chem., 46 (2008) 4070 080. 

Yallapu, M.M. Dobberpuhl, M.R. Maher, D.M. Jaggi, M. Chauhan, S.C. Design of curcumin loaded cellulose nanoparticles for prostate cancer. Curr. Drug Metab. 2012, 13 (1), 120—128. 

Neha, D. Novel cellulose nanoparticles for potential cosmetic and pharmaceutical applications. A Masters Thesis, Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada, 2010. 

In nature, fibrous biopolymers have long been used in the reinforcement of extracellular biocomposites, inspiring the reproduction of this technology using native CNs as filler in a range of host polymer matrixes. Due to the highly crystalline nature of the cellulose nanoparticles, they possess attractive mechanical properties, such as an axial Young s Modulus of around 140 GPa, which is dependent on cellulose crystallinity and axial ratio [36]. When... 

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... 

Siqueira, G., Bras, J., Dufresne, A. New process of chemical grafting of cellulose nanoparticles with a long chain isocyanate. Langmuir. 26, 402 11 (2010b)... 

Cellulose nanoparticles having a relatively low specific gravity and do not precipitate in liquid media. 

Organic cellulose nanoparticles are compatible with organic ingredients and impart to cosmetic remedies a nice texture, increased viscosity, water retention ability, and phase stability. 

The CNP of natural cellulose are the basis for a new family of smart nanoremedies used for care and cure. For example, an experimental nanocream with optimal pH = 5 containing about 5% active multifunctional cellulose nanoparticles has demonstrated excellent texture, selective and gentle mechanical peeling. 

Dhar, N., 2010. Novel Cellulose Nanoparticles for Potential Cosmetic and Pharmaceutical Applications. University Press, Waterloo, ON. 

Lambert Academic Publishing, Saarbriicken. loelovich, M., 2014a. Peculiarities of cellulose nanoparticles. TAPPI 13 (5), 45—52. loelovich, M., 2014b. Cellulose—Nanostructured Natural Polymer. Lambert Academic Publishing, Saarbriicken. 

Actually, commonly used microcrystalline cellulose is a completely different material (micron-sized cellulose crystals) [23,24,25]. However, different terminologies are used to describe these cellulose nanoparticles, leading to some misunderstandings and ambiguities. These terminologies, as well as sources of raw cellulosics and extraction processes, are summarized in Table 1.1. 

Table 1.1 The different terminologies used to describe cellulose nanoparticles [23].

Changing the surface functionality of the cellulose nanoparticle can also affect the permeability of nanocellulose films. Films constituted of negatively charged cellulose nanowhiskers could effectively reduce permeation of negatively charged ions, while leaving neutral ions virtually unaffected. Positively charged ions were found to accumulate in the membrane [70]. 

According to Rebouillat et al. [55], cellulose nanoparticles mostly have two major thermal characteristics. The onset of thermal chemical degradation usually occurs at 300°C and 260°C for freeze-dried MCC and NCC (produced via sulfuric acid hydrolysis of the same MCC) respectively. In work by different authors it has been observed that the coefficient of thermal expansion of nanocellulose reinforced composite materials was improved in which coefficient of thermal expansion of the nanoparticle in the axial direction was at 0.1 ppm/K. The value is similar to that of quartz glass. Yano et al. [74] showed that the flexible plastic composites reinforced with this renewable resource have thermal expansion coefficients of 6 x 10 °C. ... 

Another important feature of nanoparticles is the possibility to improve properties of the material for low filler content without detrimental effect on impact resistance and plastic deformation. A reduction of gas diffusion (a barrier effect) is also likely to occur. Moreover, cellulosic nanoparticles are distinguished by their hquid crystal behavior when suspended in water, presenting birefringence phenomena tmder polarized light. 

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. 

The glass-rubber transition temperature, Tg, of cellulose whisker filled polymer composites is an important parameter, which controls different properties of the resulting composite such as its mechanical behavior, matrix chain dynamics, and swelling behavior. Its value depends on the interactions between the polymeric matrix and cellulosic nanoparticles. These interactions are expected to play an important role because of the huge specific area inherent to nanosize particles. For semicrystalline polymers, possible alteration of the crystaUine domains by the cellulosic filler may indirectly affect the value of Tg. 

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