Preparation of Bionanocomposites

It is essential to point out that these clays are really attractive as reinforcing materials in the preparation of bionanocomposites, because they are not harmful to human health and they may have curative properties and can also be employed in pharmaceutical formulations (Bergaya et al. 2012). 

Preparations of Si02-chitin/carbon nanotubes (CNTs) bionanocomposites have also been reported by many researchers [90]. The use of nanomaterials such as CNTs to fabricate matrices for biosensors is one of the most exciting approaches because nanomaterials have a unique structure and high surface to volume ratio [90]. The surfaces of nanomaterials can also be tailored in the molecular scale in order to achieve various desirable properties [91]. The diverse properties of nanocomposite materials such as unique structure and good chemical stability enable them to provide a wide range of applications in sensor technology [92]. 

Fig. 3.17 Reaction scheme for the preparation of Si02-chitin/CNTs bionanocomposites [90]...

Figure 8.13 (a) Scheme of the preparation of IL-graphene. Reprinted from reference [103] by permission of The Royal Society of Chemistry, (b) Illustration showing the construction of the IL-graphene-GOD bionanocomposite. Reprinted from reference [104]. Cop3n-ight 2012, with permission from Elsevier. 

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... 

Sadegh-Hassani, F., Mohammadi Nafchi, A. Preparation and characterization of bionanocomposites films based on potato starch/halloysite nanoclay. Int J. Biol. Macromol. 67, pp. 458 62 (2014)... 

Bionanocomposites are an ecological alternative to conventional nanocomposites based on petroleum-derived polymers, as they are based on biodegradable polymers obtained from renewable resources. Biomass is the source of agropolymers like starch and cellulose and also of monomers used to chemically synthesize polymers like polylactic acid (PLA). Other kinds of biopolymers, e.g., xanthan gum and poly (hydroxyalkanoates), are produced by microorganisms. Even though most of the bionanocomposites reported in the hterature are based on layered sihcates, the number of examples illustrating the use of fibrous clays in the preparation of new bionanocomposites is growing rapidly. 

Reddy, J. R, Rhim, J. W. (2014). Characterization of bionanocomposite films prepared with agar and paper-mulberry pulp nanocellulose., 480-488. 

Russell PL (1987) Gelatinisation of starches of different amylose/amylopectin content A study by differential scanning calorimetry. J Cereal Sci 6 133-145 Sadegh-Hassani F, Nafchi AM (2014) Preparation and characterization of bionanocomposite films based on potato starch/halloysite nanoclay. Int J Biol Macromol 67 446 58 Salman H, Blazek J, Lopez-Rubio A, Gilbert EP, Hanley T, Copeland L (2009) Stmcture-function relationships in A and B granules from wheat starches of similar amylose content Carbohydr Polym 75 420-427... 

Siqueira G, Bras J, Dufresne A (2010) Cellulosic bionanocomposites a review of preparation, properties and applications. Polymers 2 728-765 Son WK, Youk JH, Lee TS, Park WH (2004) Preparation of antimicrobial ultrafine cellulose acetate fibers with silver nanoparticles. Macromol Rapid Commun 25 1632-1637 Son WK, Youk JH, Park WH (2006) Antimicrobial cellulose acetate nanofibers containing silver nanoparticles. Carbohydr Polym 65 430-434... 

Fu, Y., Li, P, Bu, L. et al (2010) Chemical/biochemical preparation of new polymeric bionanocomposites with enzyme labels immobilized at high load and activity for high-performance electrochemical immunoassay. J. Phys. Chem. C, 114,1472-1480. 

The SEM has also been used to study the fractured surface (cross-section) of bionanocomposite films (Vaz et al., 2002 Yu et al., 2007). Sample of fractured surface is prepared by freezing the film in hquid nitrogen, followed by breaking the film to expose the fracture surface, and sputter coating the fractured surface with a conducting coating (Yu et al., 2007). 

In situ polymerization is a method of bionanocomposite preparation whereby the nanostructured reinforcement, usually layered clays, is dispersed in a liquid monomer or a monomer dissolved in a suitable solvent for a certain amount of time, allowing monomer molecules to diffuse between the layers. Upon further addition of initiator or exposure of appropriate source of light or heat, the polymerization takes place in situ forming the nanocomposite. 

Although chitin can be processed in the form of films, it has been largely used as reinforcement to bionanocomposites. Chitin nanowhiskers have been used to prepare a variety of bionanocomposites with matrices such as natural rubber, PLA, PCL, PVA, silk fibroin, and chitosan [185-194], as will be discussed throughout the text below. 

PCL, is an important APES with many potential applications in biomedical and environmental fields [144]. This polymer was the first one to be studied in bionanocomposite when in the early 1990s, GianneUs group from Cornell University (Ithaca, NY, USA) started to work on the elaboration of PCL-based nanocomposites by intercalative polymerization [295]. Since then, a vast number of bionanocomposites have been prepared [87]. Several groups used intercalation, master batches, and in situ polymerization of PCL with clays to produce a variety of nanocomposites as can be seen in Table 11.2. Not only clays, but also various types of nanoreinforcements such as cellulose [296] and StNs [297, 298], chitin [299] nanowhiskers, carbon nanotubes [300, 301], and silica nanoparticles [302] have been used to prepare bionanocomposites with PCL. 

Gilberto, S. Julien, B. Alain, D. Cellulosic bionanocomposite A review of preparation, properties and applications. Polymers 2010, 2 (4), 728-765. 

Siqueira, G., Bras, J., and Dufresne, A. (2010). Cellulosic bionanocomposites A review of preparation, properties and applications,... 

In another study Feng et al. [86] presented the stmcture and properties of new thermoforming bionanocomposites based on chitin whiskers-graft-polycaprolac-tone. The synthesized material was characterized by FTIR, SEM, TEM and XRD. The surface and mechanical properties were also determined and discussed. Ha-riraksapitak et al. [87] prepared a neat hyaluronan-gelatin scaffolds and chitin-whisker-reinforced hyaluronan-gelatin scaffolds. The obtained cylindrical scaffolds obtained were about 10 mm in diameter and 2 mm in height, whereas the disc-shaped scaffolds were about 1 mm in thickness these were later cut into a desired shape and size for the mechanical property assessment. 

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