Individualization of nano-sized plant cellulose fibrils achieved by direct surface carboxylation using TEMP catalyst Department of Biomaterial Sciences The University of Tokyo Akira ISGAI
TEMP / NaBr / NaCl oxidation of polysaccharides at ph 10 Advantages points : Aqueous media at ph 10 Highly regioselective reaction at C6-H Proceeds under mild conditions (at room temp, < 2 h) Formation of some aldehyde groups CH H H ph 10 CNa H H NaCl NaBr N H NaH Glucuronic acid unit N CH H H NaCl NaBr N CH 2 H H Glucose unit TEMP-mediated oxidation proceeds similarly to enzymatic reactions but more rapidly. H
TEMP-mediated oxidation of various celluloses Water (100 ml) TEMP (0.0125 g) NaBr (0.125 g) Cellulose fibers (1 g) Cellulose fibers / water slurry at room temp. and ph 10 NaCl / water 0.4M NaH addition to keep ph 10 Isolation & washing process TEMP-oxidized cellulose Analyses
Research projects of TEMP-oxidized celluloses in our lab 1996 1998 2000 2002 2004 2006 2008 2010 2012 TEMP oxidation of various celluloses, chitins & other polysaccharides Preparation & characterization of water-soluble TEMP-oxidized cellulose (cellouronic acid) prepared from regenerated celluloses TEMP oxidation of paper pulps to improve paper properties by introducing carboxyl & aldehyde groups Preparation & characterization of TEMP-oxidized cellulose nanofibers, supported by JSPS NED Nanotech Challenge Project for high gas-barrier packaging materials JSPS Bio-Nanofibril Project for fundamental research Applying METI National Project with companies, university labs & government for new bio-nanofibers (undecided) 2014 2016
Hierarchical structure of highly crystalline cellulose in plants Tree Fiber assembly Single fiber Bundle of microfibrils Cellulose microfibril Cellulose chain Fiber surface Wood Wood tissue Width : 20 30 µm Length : 1 3 mm Width > 15 nm Width 3 4 nm Length > 5 µm Width 0.4 nm Length 500 nm Crystallinity 70 90 %
Cellulose single nano-fibers from abundant biomass resources Cellulose single nano-fiber Cellulose molecules Downsizing processing Bottom-up processing Abundant wood biomass Width 3 4 nm Length > 5 µm Crystallinity 70 90 %
ptical microphotographs of the original and TEMP-oxidized wood celluloses (never-dried) riginal wood cellulose TEMP-oxidized wood cellulose TEMP-mediated oxidation 50 µm Carboxylate content 0.05 mmol/g Carboxylate content 1.5 mmol/g Even though a significant amount of carboxylate groups is formed in TEMP-oxidized cellulose, no swelling of fibers in water is observed. Saito et al., Biomacromolecules, 2007
Metal ion content in TEMP-oxidized cotton celluloses after ion-exchange treatment TEMP-oxidized cellulose-cna TEMP-oxidized cellulose-cm Metal ion Metal ion content (mmol/g) 0.6 0.5 0.4 0.3 0.2 0.1 0.0 3+ + Mg Al Ca Mn Co Ni Cu Sr Ag Cd Ba La Pb 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 3+ 2+ Metal ion treated Pb, Ca & Ag can form carboxylate salt almost 1:1 by molar ratio. Saito & Isogai, Carbohydrate Polymers, 2005
Biodegradation of TEMP-oxidized cellulose Disintegration TEMP-oxidized cellulose suspension in water Transparent dispersion TEM observation Domestic blender at 12,000 rpm < 4 min Ultrasonic homogenizer < 2 min Magnetic stirrer at 1,500 rpm ~ 12 days 50 nm
TEMP-mediated oxidation of various native celluloses -Effective surface modification of cellulose microfibril- Plants (tree) Electrostatic repulsion Cellulose microfibrils 4-5 nm 0.5 nm Cellulose nanofiber dispersion in water Anhydroglucose unit Disintegration in water 20-30 µm Wood fiber TEMP-mediated oxidation N : -CH 2 H : Hemicellulose region TEMP : -C Na + : -CH 2 H TEMP-oxidized cellulose fibers suspended in water
100 nm Saito et al., Biomacromolecules, 2007
Wood cellulose fibers are the most suitable resources for preparing TEMP-oxidized cellulose nano-fibers Wood cellulose microfibrils Hemicellulose & disordered region N TEMP-mediated oxidation N H Glucose unit Glucuronate unit C Disintegration in water ζ-potential : 80mV
Structural model of TEMP-oxidized cellulose nanofiber riginal TEMP-oxidized wood cellulose microfibril nanofiber -CH 2 H Glucose unit 4 nm -C - Glucuronate unit 1.7 Carboxylate groups / nm 2
TEMP / NaBr / NaCl oxidation of polysaccharides at ph 10 Advantages points : Aqueous media at ph 10 Highly regioselective reaction at C6-H Proceeds under mild conditions (at room temp, < 2 h) Formation of some aldehyde groups CH H H ph 10 CNa H H NaCl NaBr N H NaH Glucuronic acid unit N CH H H NaCl NaBr N Depolymerization Discoloration etc. CH 2 H H Glucose unit TEMP-mediated oxidation proceeds similarly to enzymatic reactions but more rapidly. H
TEMP-mediated oxidation of cellulose using NaCl 2 at ph 3-7 Advantages : Aqueous media at ph 3-7 Highly regioselective reaction at C6-H No aldehydes are present in the oxidized products NaCl Proceeds under mild conditions (at 20-80 C, 2-24 h) β-elimination and depolymerization is avoidable. N N Glucose unit CH 2 H H H NaCl CH H H thers TEMP-Peroxidase-H 2 2 TEMP-Laccase- 2 NaCl 2 Glucuronic acid unit CNa H H Saito et al., Biomacromolecules, 2009
Carboxylate content and DP of TEMP-oxidized celluloses ph xidation Carboxylate time (h) content (mmol/g) DP riginal wood cellulose ー 0.10 1,260 xidized celluloses prepared by TEMP/NaCl/NaCl 2 6.8 2 0.65 1,100 6.8 18 0.71 1,000 6.8 54 0.78 910 xidized celluloses prepared by TEMP / NaBr / NaCl 10 0.1 0.44 220 10 0.3 0.93 200 DP values were determined by cuen viscosity method TEMP-oxidized celluloses prepared at ph 6.8 by TEMP / NaCl / NaCl 2 had higher DPs, although longer oxidation times were required. Saito et al., Biomacromolecules, 2009
100 nm
Size map of new TEMP-oxidized cellulose nano-fibers (TCN) prepared from native celluloses 1000 Bacterial cellulose CNT TCN 100 nm Length / diameter ratio 100 10 CNT TCN Hydrolyzed cellulose whisker Mechanically fibrillated cellulose 1 10 0 10 1 10 2 10 3 10 4 10 5 Diameter (nm) Rayon fibers Microcrystalline cellulose TCN covers new nano-fiber region at nm-level diameters in the map, which has not been prepared from other polymers or by other processes.
Differences in morphology and consumed energy between micro-fibrillate cellulose and TEMP-oxidized cellulose nano-fibers Micro-fibrillated cellulose TEMP-oxidized cellulose nanofibers 100 µm 100 nm Disintegration energy > 200 khw / kg More than 10 times cycles by highpressure homogenizer Disintegration energy < 2 khw / kg
ptical transparency of a TCN film 100 Transmittance (%) 80 60 40 20 0 200 400 600 800 1000 Wavelength (nm) The TCN films obtained are transparent and bendable. Fukuzumi et al., Biomacromolecules, 2008
Coefficient of thermal expansion of TCN film 0.025 0.020 2.7ppm / K Expansion (%) 0.015 0.010 0.005 0.000 40 60 80 100 Temperature ( C) The extremely low CTE of TCN films is available for electronic and flexible display devices. The CTE of glass is ca. 8 ppm / K. Fukuzumi et al., Biomacromolecules, 2008
Changes in water contact angle on TCN films by 0.05% AKD treatment 120 Contact angle ( ) 100 80 60 40 20 0.05% AKD-treated TCN film riginal TCN film 0 0 2 4 6 8 10 Time (s) The surface hydrophilicity of TCN films is controllable by simple soaking treatment in AKD dispersion and drying. Fukuzumi et al., Biomacromolecules, 2008
NED Nanotech Challenge Programs Stage I from 2007 to 2010 Project title NED: New Energy and Industrial Technology Development rganization of Japan, and is an affiliated organization of Ministry of Economy, Trade and Industry Development of environment compliant high-capability packaging components using cellulose single nano-fiber rganizations: Kao Corporation, Nippon Paper Industries, The University of Tokyo Project Leader: Akira Isogai (The University of Tokyo) utline: TEMP-oxidized cellulose single nanofibers (TCN) are new biobased nano-materials with various potential applications. During the development research of applying TCN to environmentallycompatible and high-performance packaging components, we work toward the creation of sustainable society. http://app3.infoc.nedo.go.jp/informations/koubo/kaiken/be/nedopressorder.2009-02-10.0007481708/cellulose.pdf
Development of environment compliant high-performance packaging components using TEMP-oxidized cellulose single nano-fibers (NED project) Background General waste in Japan 5.2 Mt / y Electricity / machinery 0.18 Mt 3.4% Household 1.05 Mt, 20.2% thers 0.3 Mt, 5.8% Containers/ packaging 3.67 Mt, 70.6% thers 0.21 Mt 3% Household commodity 0.19 Mt, 3.9% Agriculture Forestry Fisheries 0.19 Mt 3.9% Transportation 0.33 Mt, 6.8% Industrial waste in Japan 4.9 Mt / y Production Processing waste 0.92 Mt 18.9% Building products 0.71 Mt 14.6% Electricity Machinery 1.2 Mt, 24.7% Containers packaging 1.14 Mt 23.5% TEMP N 100 nm Wood cellulose Incineration disposal: 53% (5.4 Mt/y) TEMP-oxidized cellulose nanofibers C 2 emission: 6.7 M t / year New environmentally compatible packaging materials are needed. Matching Goal Development of environmentally friendly packaging materials with high-bas barrier properties, from TEMP-oxidized cellulose nanofibers and bioplastics http://app3.infoc.nedo.go.jp/informations/koubo/kaiken/be/nedopressorder.2009-02-10.0007481708/cellulose.pdf