Preparation of Cellulose Nanocrystals and Their Applications in Inorganic Nanocomposites
Content
1 Cellulose Nanocrystals
2 Chemical preparation methods of CNCs
4 Outlook
• CNC as a new kind of biomass nano materials, since it has many excellent physical and chemical properties and is rich in nature, having wide applications in areas such as biology, medicine, material, catalyst. • There are still a lot of composites， combinaed rod CNCs ，organic polymer materials or inorganic materials together，are not explored. We can believe that more CNCs related composite materials will be exploited .
CNCs are generally refer to the rod-shaped cellulose crystals with length from 100 nm to 1–2um and width varying from 5 to 20 nm. They can be extracted from a broad range of natural sources including cotton ,tunicate ,bacteria and wood.
Nano Pd[3]
Nano Au[4]
Nano Silver[5]
3 Applications in Inorganic Nanocomposites The most common method for the deposition of metallic nanoparticles is the treatment of metallic salts with reducing agents ，for example NaBH4
Oxidation method
Inorganic persulfate method Potassium persulfate, ammonium persulfate or their mixture
3 Applications in Inorganic Nanocomposites CNCs suspension has the very good porosity, it can promote the nucleation of nanoparticles, prevent agglomeration to achieve a very narrow particle size distribution, and make them can be used for the preparation of precious metal or its alloy nanoparticles.
2 Preparation of CNCs-chemical methods
Acid hydrolysis method
Chemical preparation methods of CNCs
Enzymatic hydrolysis method
Oxidation method
2 Preparation of CNCs-chemical methods
Acid hydrolysis method
waste acid and other useless components were formed
Acid hydrolysis
Crystalline regions
The acids can be H2SO4,HCl,H3PO4, HCOOH,or their mixed acids
3 Applications in Inorganic Nanocomposites Antimicrobial and medical application
Microbial cellulose has attracted attention as a novel biomedical material due to its biocompatibility, good strength and high water holding capacity.
Tunicate[1]
Cotton[2]
1 Cellulose Nanocrystals
Aபைடு நூலகம்undant
High crystalline order
Nanoscale dimension Large surface area
Low cost, availability, renewability
Superior mechanical strength
Mild Environmental-friendly Longer time consuming
2 Preparation of CNCs-chemical methods
TEMPO-mediated TEMPO,2,2,6,6-tetramethylpiperidine-1-oxyl radical, in combination with NaBr and NaClO.
Thanks!
3 Applications in Inorganic Nanocomposites Enzyme immobilization CNCs have been proposed as an agent for protein/enzyme immobilization due to its large surface area and nonporous structure.
disrupt bacterial metabolism
3 Applications in Inorganic Nanocomposites
Catalyst support
Nano Pd ,Au or their alloy supported on cellulose Highly efficient recyclable heterogeneous catalyst Excellent stability (both chemical and thermal), high surface area, good accessibility, and organic groups can be robustly anchored to the surface to provide catalytic centres.
CNCs can also be used to prepare silver colloidal suspensions with antimicrobial properties
Hydrogel s spheres, films,and tubes， artificial blood vessels
3 Applications in Inorganic Nanocomposites
4 Outlook
1 Cellulose Nanocrystals( cellulose microcrystals ，cellulose whiskers ，nanocellulose crystals or
nanocrystalline cellulose )
2 Preparation of CNCs-chemical methods
Enzymatic hydrolysis method
Cellulase is a kind of multi-components mixture,containing different enzymes, these enzymes cooperate with each to selectively hydrolyze the amorphous regions leaving the crystalline region.
Reference
[1] Lu P, Hsieh YL. Preparation and properties of cellulose nanocrystals: Rods, spheres, and network[J]. Carbohydrate Polymers, 2010,82(2): 329-336. [2] Khalil HPSA, Bhat AH, Yusra AFI. Green composites from sustainable cellulose nanofibrils: A review[J]. Carbohydrate Polymers, 2012,87(2): 963-979. [3] Ciprian M. Cirtiu.Cellulose nanocrystallites as an efficient support for nanoparticles of palladium: application for catalytic hydrogenation and Heck coupling under mild conditions. Green Chem., 2011, 13, 288–291 [4] Koga H, Tokunaga E, Hidaka M, et al. Topochemical synthesis and catalysis of metal nanoparticles exposed on crystalline cellulose nanofibers[J]. Chemical Communications, 2010,46(45): 8567-8569. [5] Jie Cai.Nanoporous Cellulose as Metal Nanoparticles Support. Biomacromolecules2009,10,87– 94