Synthesis and Characterization of Novel Cellulosics

Transcription

1 Synthesis and Characterization of Novel Cellulosics

2 Problem statement Petroleum based polymeric materials Limited existing quantities of fossil supplies Escalating cost Problem of non biodegradability of petroleum based polymers The recent environment conservative regulations. lti Natural polymers Renewable Environment friendly Contain many functional groups suitable to chemical functionalization Cost effective 2

3 Background Cellulose is the most abundant renewable biopolymer. Over ~10 10 tons are produced per year and only 3% are explored. Linear homopolymer of D anhydroglucopyranose units tsconnected by β(1 4) ) glycosidic gycosdclinkages Cellulose Semicrystalline in nature High degree of polymerization (DP) Cellulose source DP Cotton Wood Pulp Valonia Rayon 300 Bagasse Acetobacter xylinum

4 Cellulose Cellulose exists in four different polymorphs I (I α, I β ), II, III, IV Hydrogen bonds of cellulose I cellulose II S. Kamel et al. Polymer Letters, 2008, 2, M. De Souza Lima et al.. Macromolecular Rapid Communication, 2004, 25,

5 Cellulose I and II particle types Particle Type Particle size Length (μm) Width(nm) Crystallinity (%) Wood fiber & Plant fiber > Microcrystalline cellulose (μm) Microfibrilated il Nanofibrilated Cellulose Cellulose nanocrystals Algae cellulose Bacterial cellulose Cellulose II s > > Regenerated cellulose > R. J. Moon, A. Martini, J. Nairn, J. Simonsen and J. Youngblood, Chem. Soc. Rev., 2011, 40,

6 Applications of cellulose fiber derivatives Cellulose esters Cellulose ethers Oxidized cellulose Films, fibers, explosives coatings, heat resistant fabrics Food additives, fibers, coatings, g, oil well drilling, gelling and foaming, paints, detergents, cosmetics, controlled release drug tablets Wound dressing, pharmaceutical, skin care S. Kalia et al. (eds.), Cellulose Fibers: Bio and Nano Polymer Composites, Springer Verlag Berlin Heidelberg

7 Cellulose beads Important features of bead cellulose Excellent mechanical stability Rigid spherical particles Narrow particle size distribution Highchemical resistance andcompatibility with most commonly used solvents High temperature stability High selectivity of separation Cellulose fiber solution Regeneration Bead cellulose Application of bead cellulose Metal adsorption Immobilization support Chromatography Drug delivery D. Zhoua, L. Zhanga and S. Guo, Water Res. 39, 3755 (2005). W. De Oliveira and W. Glasser, J. Appl. Polym. Sci. 60, 63 (1996). V. Weber, I. Linsberger, M. Ettenauer, F. Loth, M. Höyhtyä and D. Falkenhagen, Biomacromolecules 6, 1864 (2005) 7

8 Cellulose nanowhiskers (CNWs) Cellulose nanowhiskers are defined as crystalline rod like nanoparticles which are obtained by acid hydrolysis of cellulose fibers Plant cell Microfibril 200nm Acid hydrolysis G. Siqueira, J. Bras, A. Dufresne, Biomacromolecules 2009, 10, M. A. S. Azizi Samir, F. Alloin, A. Dufresne, Biomacromolecules 2005, 6, S. Beck Candanedo, M. Roman, D. G. Gray, Biomacromolecules 2005, 6, M. M. de Souza Lima, R. Borsali, Macromol. Rapid Commun. 2004, 25,

9 Cellulose nanowhiskers (CNWs) Acid Hydrolysis H 2 SO 4 /HCl O HO O HO O O HO HO O HO O O H 2 SO 4 Chracteristics of CNWs Nano dimension High aspect ratio High surface area High mechanical property Y. Li, A. Ragauskas, Advance in diverse applications of nanocomposites 2011, pp

10 Cellulose nanowhiskers The geometric dimensions depend on the source of the cellulosic material and hydrolysis conditions. Cotton Ramie Wood Tunicate L/D=11.8 L/D=28.6 L/D=25.0 Dimensions: Length: nm; Diameter: 4 50 nm. L/D=67.0 Habibi, Y.; Goffin, A. L.; Schiltz, N.; Duquesne, E.; Dubois, P.; Dufresne, A. J. Mater. Chem. 2008, 18, Azizi Samir, M. A. S.; Alloin, F.; Paillet, M.; Dufresne, A. Macromolecules 2004, 37, Roohani, M.; Habibi, Y.; Belgacem, N. M.; Ebrahim, G.; Karimi, A. N.; Dufresne, A. Eur. Polym. J. 2008, 44, 2489.Favier, V.; Canova, G. R.; Cavaille, J. Y.; Chanzy, H.; Dufresne, A.; Gauthier, C. Polym. AdV. Technol. 1995, 6,

11 Effect of reaction parameters on cellulose nanowhiskers properties Effect of reaction conditions on whisker properties (H 2 SO 4 hydrolysis, softwood pulp) Reaction conditions (reaction time (min), acid/pulp) Length Aspect Sulfur Surface charge (nm) ratio content(%) density (e/nm 2 ) 25, ± ± ± , ± ± ± , ± ±0 1.26± Sample Amounts of acidic groups on surface (mmol kg 1 ) Strong acid Weak acid groups groups H 2 SO HCl 0 <18 TEM images of (a) H 2 SO 4 (b) HCl hydrolyzed whiskers J. Araki et. al. Colloids Surfaces A, 1998, 142, J. Araki et. al. J. wood Sci. 1999, 45,

12 Cellulose nanowhiskers potential areas of application Nanocomposites Paper & Paperboard Biomedical Packaging, Adhesive Electronic displays, Foams Aerogels, Films Coatings / barriers Bioimaging nanodevice, drug delivery technology, skin care Arboranano* is a new Canadian Forest NanoProducts Network whose objective is to develop high value products from nanocrystalline cellulose. *Canada s Business led ldnt Networks of Centers of Excellence program, FPInnovations and NanoQuébec. 12

13 Typical chemical modification of cellulose Substitution Oxidation Acid hydrolysis Oxidative cleavage of C 2 C 3 glycol l Substitution Oxidation Cellulose Dialdehyde cellulose (DAC) Mild reaction Highly selective DAC acts as a reactive intermediate 13

14 Research Studies To investigate and explore the versatility of cellulose, a renewable resourceofraw of raw materials usingperiodateoxidative oxidative fragmentation synthetic approach Chemical modification of cellulose through periodate oxidation Cellulose fibers Cellulose beads Cellulose nanowhiskers 14