Polysaccharides nanocrystals

Lin N, Huang J, Chang PR et al (2011) Effect of polysaccharide nanocrystals on structure, properties, and drug release kinetics of alginate-based microspheres. Colloids Surf B 85 270-279... 

Lin N, Huang J, Dufresne A (2012) Preparation, properties and applications of polysaccharide nanocrystals in advanced functional nanomaterials a review. Nanoscale 4 3274—3294... 

In tissue engineering, the bionanocomposite scaffolds comprising polysaccharide nanocrystals can be used as carriers for the localized and controlled release of hioactive compounds, such as growth factors, proteins. 

As previously mentioned, natural fibres present a multi-level organization and consist of several cells formed out of semi-crystalline oriented cellulose micro fibrils. Each microfibril can be considered as a string of cellulose crystallites, linked along the chain axis by amorphous domains (Fig. 19.10) and having a modulus close to the theoretical limit for cellulose. They are biosynthesized by enzymes and deposited in a continuous fashion. A similar structure is reported for chitin, as discussed in Chapter 25. Nanoscale dimensions and impressive mechanical properties make polysaccharide nanocrystals, particularly when occurring as high aspect ratio rod-like nanoparticles, ideal candidates to improve the mechanical properties of the host material. These properties are profitably exploited by Mother Nature. 

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]. 

This technique is also a kind of casting and evaporating technique which is used for polysaccharides modified by various surface chemical reactions. With improved hydrophobicity, these nanocrystals can disperse in non-aqueous solvents and be more compatible with hydrophobic polymers. Therefore, non-aqueous solution mixing techniques are possible for preparing well-dispersed polymer/polysaccharide nanocrystals nanocomposites. 

Greiner A, Wendorff JH (2007) Electrospinning a fascinating method for the preparation of ultrathin fibers. Angew Chem Int Ed 46 5670-5703 Grunnert M, Winter WT (2002) Nanocomposites of cellulose acetate butyrate reinforced with cellulose nanocrystals. J Polym Environ 10 27-30 Habibi Y, Dufresne A (2008) Highly filled bionanocomposites from functionalized polysaccharide nanocrystals. Biomacromolecules 9 1974-1980... 

Dong XM, Revol JF, Gray DG (1998) Effect of microcrystallite preparation conditions on the formation of colloid crystals of cellulose. Cellulose 5 19-32 Dubief D, Samain E, Dufresne A (1999) Polysaccharide microcrystals reinforced amorphous poly (beta-hydroxyoctanoate) nanocomposite materials. Macromolecules 32 5765-5771 Dufresne A (2000) Dynamic mechanical analysis of the interphase in bacterial polyester/cellulose whiskers natural composites. Compos Interface 7 53-67 Dufresne A (2003) Interfacial phenomena in nanocomposites based on polysaccharide nanocrystals. Compos Interface 10 369-387... 

Habibi Y, Dufresne A. Highly filled bionanocomposites from functionalized polysaccharide nanocrystals. Biomacromolecules 2008 9 1974-1980. 

PROCESSING OF POLYMER NANOCOMPOSITES REINFORCED WITH POLYSACCHARIDE NANOCRYSTALS... 

The homogeneous dispersion of cellulose nanoparticles in a polymer matrix in order to obtain nanomaterials is due to their size, which allows penetration in hydrosoluble or at least hydrodispersible structures (as latex-form polymers) as well as dispersion of polysaccharide nanocrystals in nonaqueous media especially using surfactants and chemical grafting. Thus, one of the processing techniques of polymer nanocomposites reinforced with polysaccharide nanocrystals was carried out using hydrosoluble or hydrodispersible polymers. In this respect, the literature has reported preparation of polysaccharide particles with reinforced starch (Svagan et al. 2009), silk fibroin (Noishiki et al. 2002), poly(oxyethylene) (POE) (Samir et al. 2006), polyvinyl alcohol (PVA) (Zimmermann et al. 2005), hydroxypropyl cellulose (HPC) (Zimmermann et al. 2005), carboxymethyl cellulose (CMC) (Choi and Simonsen 2006), or soy protein isolate (SPI) (Zheng et al. 2009). 

The preparation procedures of polysaccharide nanocrystal reinforced polymer nanocomposites using latexes consist of mixing and casting the two aqueous suspensions, followed by... 

Dufresne Alain. Polysaccharide nanocrystal reinforced nanocomposites. Can. J. Chem. 86 no. 6 (2008) 484-494. 

Dufresne Alain. Processing of polymer nanocomposites reinforced with polysaccharide nanocrystals. Molecules. 15 no. 6 (2010) 4111-4128. 

Deepa B, Abraham E, Cherian BM, Bismark A, Blaker JJ, Pothan LA, Leao AL, de Souza SE, Kottaisamy M (2011) Structure, morphology and thermal characteristies of banana nano fibers obtained by steam explosion. Bioresour Technol 102(2) 1988-1997 Dufresne A (2010) Processing of Polymer Nanocomposites Reinforced with Polysaccharide Nanocrystals. Molecules 15 4111-4128... 

Li Q, Zhou J, Zhang L (2009) Structure and properties of the nanocomposite films of chitosan reinforced with cellulose whiskers. J Polym Sci 47 1069-1077 Lin N, Yu J, Chang PR, Li J, Huang J (201 la) Poly(butylene succinate)-based biocomposites filled with polysaccharide nanocrystals Structure and properties. Polym Compos 32 472-482 Lin M-F, Thakur VK, Tan EJ, Lee PS (2011b) Surface functionalization of BaTiOa nanopaiticles and improved electrical properties of BaTi03 1yvinylidene fluoride composite. RSC Adv 1 576-578... 

---