DENSE AND POROUS NANOFIBRILLATED CELLULOSE (NFC) SUBSTRATES

Transcription

1 DENSE AND POROUS NANOFIBRILLATED CELLULOSE (NFC) SUBSTRATES P. Orsolini 1,2, C. Antonini 1, T. Geiger 1, T. Zimmermann 1, W. R. Caseri 2 1 Empa 2 ETH-Zürich Applied Wood Materials Functional Cellulose Materials Überlandstrasse Dübendorf Switzerland Multifunctional Materials Laboratory Wladimir-Prelog-Weg 1-5/ Zürich Switzerland

2 Outline About Our Group Framing of PhD Project NFC dense membranes: a porosity study Enhance porosity of dense NFC membranes Chemical modification of porous NFC substrates Outlook 2

3 Swiss Federal Laboratories for materials Science and Technology 3

4 Ø Vision: Development of functional wood and cellulose based materials with economic impact

5 Framing of PhD Project 5

6 Materials for sustainable building CO2 capture for air purification Environmental Remediation Membranes / foams for water purification Acoustic and thermal insulation (buildings) NFC Packaging (barrier) and in composites (filler) Nanostructured materials Water repellency in coatings and films Improve performance properties of wood coatings Surface Technology courtesy of Dr. Sehaqui

7 Environmental Remediation Part 1 How to characterize porosity Membranes / foams for water purification NFC Part 2 How to master porosity (i.e. drying process, templating approach) Part 3 Tune amphiphilicity of cellulose (chemical modification) PhD Thesis : Porous nanofibrillated cellulose functional materials 7

8 Part 1 How to characterize porosity Selection of cellulose source and evaluation of porosity of dense NFC films 8

9 Preparation of NFC suspension, dense films and membranes Vacuum filtration Hot-pressing 120 C Dense NFC membrane Density 1.50 g/cm 3 Cross-section Top-view Porosity P<5% Dry Wet 9

10 Characterization methods for porosity and PSD Main concerns 1. Techniques are limited in evaluation ranges 2. Microscopy: results user-dependent 3. Hydrophilicityofcellulose (affects values) 4. Swollen state of NFC not considered (N 2 ads.) Assess techniques against known materials Mesoporous /mesostructured silicas Av. Size 15 nm Davisil Av. Size 6-8 nm SBA Counts (#) Silica Gel 60 MSU-H Pore diameter (nm) Av. Size 6 nm Av. Size 7.1 nm 3 users (4 SEM images) large error bars 10

11 Mercury Intrusion Nitrogen adsorption Reference materials (silicas) Thermoporometry Relative pore volume (mm 3 /g) Davisil Silica Gel 60 MSU-H SBA-15 dv(d) (mm3/nm/g) Davisil Silica Gel 60 MSU-H SBA Pore diameter (nm) Pore diameter (nm) Relative pore volume (mm3/g) SBA-15 MSU-H Davisil Silica Gel Pore diameter (nm) Dense NFC membranes Relative pore volume (mm 3 /g) NFC mem1 NFC mem 2 NFC mem3 NFC mem Pore diameter (nm) Relative pore volume (mm 3 /nm/g) C - 15 h 90 C - 15 h 90 C - 45 h Pore diameter (nm) Relative pore volume (mm 3 /g) Mem 5 hours Mem 24 hours Mem 200 hours Pore diameter (nm) Ref. materials reproducible results, not for NFC membranes (state-dependent) 11

12 Part 2 Howto master porosity (i.e. drying process, templating approach) Tuning porosity of dense NFC films Preparation of membranes by a templating approach 12

13 Permeance of dense membranes and templating approach SELECTIVITY f (pore size) PERMEABILITY f (thickness, porosity) Dense membranes Solvent: water Permeance (L/(h m 2 MPa) Permeance of dense NFC membranes Prepared from water Time (sec) Permeance GR 30 Permeance GR 50 Calcium Carbonate (CaCO 3 ) Nanoparticles Easy to produce Templated membranes Solvent: Ethanol Easy to remove RSC Adv., 2014,4,

14 Synthesis of CaCO 3 template and size characterization Nanoparticles in Ethanol CaCl 2 2H 2 O + CO 2 + NH 3 + H 2 O CaCO 3 2H 2 O + 2NH 4 Cl 2 NH 4 HCO 3 NH 3 + CO 2 +H 2 O Chen et al., Chem. Commun., 2013, 49, nm d av = 68 ± 8.2 nm intensity % Batch d (nm) Templated membranes preparation and template removal Mixing CaCO 3 nanoparticles and NFC Template removal Filtration (WATER PERMEANCE)! "#! "$% = & ' ; & &* ; & '* Dipping 1 M HCl, 30 14

15 Testing templated NFC membranes BEFORE Template removal TOP AFTER Template removal TOP For membranes Gr 30, ratio 1/5 P ~ 500 L/ hm 2 MPa (Gr 30 in water, P ~ 17 L/ hm 2 MPa) Permeance (L/h m 2 MPa) t (min) Gr 30 Reference ratio 1/5 ratio 1/10 ratio 1/50 For membranes Gr 100, ratio 1/5 P ~ 120 L/ hm 2 MPa (Gr 100 in water, P ~ 5 L/ hm 2 MPa) Additional Evaluations MWCO 2-components separation Peremance(L/h m 2 MPa) Gr t (min) Reference Ratio 1/5 Ratio 1/10 Ratio 1/50 15

16 Part 3 Tune amphiphilicity of cellulose (chemical modification) Chemical modification by silane chemistry Applications for environmental remediation 16

17 Superhydrophobization of NFC substrates with silane combine silane chemistry + substrates topography SUPERHYDROPHOBICITY Dense membranes Foams Porous membranes On NFC fibers 50 μm 50 μm 50 μm 50 μm SSA < 1m 2 /g SSA = m 2 /g SSA > 100 m 2 /g Increasing Specific Surface Area (SSA) for Oil absorption or separation processes Readapted from: Microelectronic Engineering, (3): p Exploit different substrate s topography 17

18 Dense membranes M [43 %RH] Foams 0.4 M [43 %RH] Porous Membranes M [43 %RH] On NFC fibers 100 μm 100 μm 100 μm Coming Soon! 3 μm 3 μm 3 μm ~ 40 times Ads. Capacity g/g

19 Conclusions and Outlook Part 1 How to characterize porosity Part 2 Howto master porosity (i.e. drying process, templating approach) Part 3 Tune amphiphilicity of cellulose (chemical modification) Characterization method of NFC porous substrates dependent of application (dry or wet state) CaCO 3 -templating increased permeances of several hundreds folds for membranes applications silane chemistry allowed superhydrophobicity and opens the way for several applications Work completed P. Orsolini et al., Acs Appl Mater Inter 2015, 7 (46), Paper Submitted Work to be completed To be submitted 19

20 Acknowledgements 1. Dr. B. Michen (ETH, Wood Materials Science) 2. Dr. Stojanovic (EMPA, Building Energy Materials and Components) 3. E. Strub, A. Huch (EMPA, Applied Wood Lab) 4. E. Marty* and T. Marchesi D Alvise* (EMPA, Applied Wood Lab) *former members of Abt. 302 Thank you for your attention! 20