Presented by : Chloé Maury, Chemistry Master s Claude Daneault, Professor Khalil Jradi, Research associate 2014 SWST International Convention Tuesday, June 24 th 2014 1
Current context Global economic crisis in the pulp and paper industry Development of new products Valorization of cellulosic fibers in materials * H. Baril. 2013. «Pâtes et papiers : moins de papier, plus de technologie», mapresse. ** Conseil de l'industrie forestière du Québec, Association canadienne des produits forestiers 2
Sonoreactor Development of a sonoreactor Massive production of cellulose nanofibers Oxidation of the Kraft pulp by 4 acetamido 2,2,6,6 tetramethylpiperidine 1 oxyle (TEMPO) Yield of 90 % and nanocellulose with a diameter of 4 nm * A. Rattaz et al. 2011. Cellulose. 18; 585-593. ** S.-P. Mishra, et al. 2011. Bioresources. 6 (1); 121-143. 3
Objectives To obtain biodegradable and ecofriendly materials To replace oil products To re use the assembly line in papers and pulp industries 4
Advantage of nanocellulose Advantage of SiO 2 Specific large surface Carboxylates and hydroxyls moieties (reactivity) Biodegradable and ecofriendly Reinforcement agent Sensors Piezoelectric Optical properties Nanocellulose/SiO 2 composite could be suitable in practical applications as the film paint industry, optoelectronic papers, piezoelectric, optical materials 5
Fabrication of TOCgel Cellulose fiber Macrofibers Microfibers Bleached Kraft pulp TEMPOmediated oxydation 1 4 acetamido - TEMPO Glucose chains Oxidized cellulose fibers Carboxylates density = 1,2 mmol/g TOCgel (3 %) 2 Mechanical defibrillation (High shear dispersion) 6
Elaboration of hybrid material (covalent route) EDC + NHS APTES TOCgel in water 30 min ph 5 Activated TOCgel in water 60 min ph 8 To filter To rinse off To disperse anew in water TEOS to small fraction To filter To rinse off To dry 90 min APTES-g- TOCgel in water 7
Characterization Silica powder TOCgel TOCgel/silica hybrid material SEM: to observe the morphology FTIR spectroscopy: to identify the chemical bonds Tensile tests: to study the mechanical properties TGA: to analyse the thermal stability 8
Synthesis of amine grafted silica + ammonia + APTES Classic Stöber method Modified Stöber method Monodisperse system observed in the both cases APTES acts as a good catalysis for the hydrolysis of TEOS in synthesis of silica APTES could replace ammonia solution APTES contribute clearly to the formation of amine grafted silica (silica 9 NH 2 )
APTES agent could be used as : 1. Catalyst : to promote the hydrolysis/condensation process of TEOS molecules 2. Surface modifier : to introduce amine moieties onto silica In the elaboration of hybrid material : Silica TOCgel network APTES could be used a crosslinking agent to covalently attached silica onto TOCgel network 10
Proposition to form TOCgel/silica APTES is chemically bound to the carboxylates group of the TOCgel Addition of TEOS is going to engender the growth of silica 11
Chemical hybrid materials 85 TOCgel APTES-g-TOCgel Amide II Transmittance (%) 80 75 70 Carbon chains 65 60 3600 2700 1800 900 Wavenumber (cm -1 ) 1543 cm -1 : amide II (C N/N H) 2800 2950 cm -1 : aliphatic carbons 1730 cm -1 : reduction of the COOH band COOH band APTES was successfully grafted onto the surface of the TOCgel 12
TOCgel/silica SEM analysis of the novel materials showed that functionalized silica is coating cellulosic fibers predominantly in the form of a dense film (homogenous film) The fibers network of TOCgel membranes and silica spherical particles (500 nm diameters) embedded in the fibers structure are clearly observed 13
Comparison silica without and with nanocellulose silica without TOCgel silica with TOCgel In the both case, systems are monodisperse Pure silica and silica in the hybrid material have approximately the same range of particle diameter (500 600 nm) 14
Mechanical properties Stress (MPa) 60 30 0 TOCgel TOCgel/silica NPs (chemical route) The TOCgel load in the composite film improved both tensile strength and elongation at break and consequently, renders the film more flexible 0 2 4 6 Strain (%) The improved mechanical properties of TOCgel/silica composite films that were observed could be explained by the contribution of the excellent mechanical properties of the TOCgel material loaded in the silica matrix 15
Thermal stability Weight (%) 100 80 60 40 20 0 Pure TOCgel TOCgel/silica NPs hybrid material APTES-g- TOCgel 200 400 600 800 1000 Temperature ( C) Thermal stability of TOCgel was clearly enhanced after grafting of APTES and after deposition of silica particles The silica particles amount present in the hybrid material was estimated to be about 12 % w/w Silica incorporated into TOCgel could be considered as a good candidate to enhance the flame retardant of TOCgel TOCgel/silica hybrid material has a high thermal stability than pure TOCgel 16
Conclusions A modified Stöber method was developed to elaborate the TOCgel/silica through a simple and efficient procedure sol gel technique. APTES plays two roles : 1. Surface modifier, APTES was used to introduce amine moieties onto silica ; 2. Catalyst, to initiate/enhance the hydrolysis and condensation processes and consequently induce the growth of silica. APTES molecules were successfully covalently coupled to the TOCgel surface (amidation) ; FTIR and SEM techniques confirmed the grafting state of APTES-g- TOCgel. Thanks to the high mechanical properties of TOCgel, the former composite shown a good mechanical behaviour. APTES grafted TOCgel and corresponding composites showed a higher thermal stability more than the pure TOCgel. The former composite could be suitable in optical devices, as prospective materials for thermal insulation or packing purpose. 17
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Oxidation of cellulose mechanism cellulose TEMPO 19
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Consumption of 2 moles of sodium hypochlorite and formation of 2 moles of sodium chloride TEMPO and sodium bromide recovery Using TEMPO in catalytic quantity and NaOCl in excess * T. Kitaoka, et al. 1999. Nordic Pulp Paper Res. J., 15 (3); 177-182. ** J. Leroux, et al. 2006. Pulp Paper Cano. 107 (4); 138-142. 21
APTES TEOS TOCgel eau 10 min 80 min APTES + TEOS + eau To filter To rinse off To enforced air dry 22
750 2 particle size (nm) 500 250 silica weight (g) 1 with NH 3 with APTS with NH 3 with APTES 0 1 2 3 amount of catalysis (ml) 0 1 2 3 amount of catalysis (ml) Size particle and yield appear to be more important in the case of APTES An excess of APTES does not increase the diameter of silica obtained by the modified Stöber method 23
To replace ammonia solution 80 silica-nh 2 silica Transmittance (%) 60 40 20 Carbone chains Amine moieties Si OH 1575 cm -1 : amine moieties ( NH 2 ) 2870 2940 cm -1 : aliphatic chain 940 cm -1 : disappearance of Si OH groups 0 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber (cm -1 ) 24
Effect of ammonia solution on fibers Without ammonia With ammonia Any chemical degradation of the TOCgel has been occurred after ammonia treatment Transmittance (%) 120 110 100 90 Some physical alteration as observed as mentioned in SEM images 80 TOCgel TOCgel/ammoniac 70 4000 3500 3000 2500 2000 1500 1000 500 wavenumber (cm -1 ) 25
TOCgel/silica mechanism (covalent route) Covalent coupling of APTES molecules onto the TOCgel network (amidation process) APTES molecules coupled on the surface of TOCgel act as nucleation sites for the growth of silica 26