Free standing Multilayer Thin Film of Cellulose Nanocrystals Chaoyang Jiang Department of Chemistry The University of South Dakota Edmonton, June 25, 2009
Cellulose Nanocrystals Nanotechnology R&D Priority for the forest product Nanocomposite thin films by Layer-by-layer assembly. Assembly, Characterizations, & Applications 2
Layer by Layer Assembly Spin assisted LbL K. Char, et al. Adv. Mater. 2001, 13, 1076. H.-L. Wang, et al. Adv. Mater. 2001, 13, 1167. G. Decher, et al. Science 1997, 277, 1232. Precise control components and film thickness Simple, cheap, versatile, can be fabricated in wet chemistry lab Suitable for various nanoscale building block Great potentials for multifunctional materials 3
Layer by Layer Assembly Rubner and Cohen MIT CEN, 2005, 83(38), 34. Saraf U Nebraska Science, 2006, 312, 1501. Kotov, U Michigan Nature Mater. 2003, 2(6), 413. 4
Free standing LbL Films V. Kozlovskaya, et.al., Macromolecules 2005, 38, 4828. C.Jiang, et.al. Adv. Mater. 2006, 18, 829. Y. G. Guo, et. al., Adv. Funct. Mater. 2005, 15, 196. 5
Free Standing Films What is free-standing film? A thin film can be self-supported without solid support Why free-standing is important? valves, barriers, and filters in microfluid channels membranes for mechanical sensors. What kind of materials can be freely stood? Enough mechanical stability Enough chemical stability How to make free-standing films? C.Jiang, et.al. Adv. Mater. 2006, 18, 829. V. V. Tsukruk, et al. Biomacromolecules, 2001, 2, 304. 6
Free standing LbL Thin Films Sacrificial Layer Acetone Spin-assisted LbL Sacrificial Layer method Freely Suspended LbL nanomembranes 7
Composite LbL Nanomembrane C. Jiang et al., Nature Mater.. 2004, 3(10), 721. 8
Free standing LbL Thin Films ngn n = 3, 5, 7, 9, 11, 80 + - + - + - + (PAH-PSS) n PAH/Au/(PAH-PSS) n PAH 2 nm Thickness (nm) 60 40 20 C. Jiang, et al. Nature Mater. 2004, 3, 721. 0 0 4 8 12 Number of PAH-PSS bilayers 9
Bulging Test Bulging results and elastic modulus Without Gold With Gold 400 μm Mechanical parameters for different freely suspended nanomembranes Membrane type and Gold content Fabricatio n method Membrane diameter (μm) Elastic modulus (GPa) 9G9, 3.9% SA-LbL 400 6.6±3.3 9G9, 0.5% SA-LbL 400 4.3±2.0 9_9, 0% SA-LbL 400 1.5±1.0 9G9, 4% LbL N/A * N/A* * Film was broken into small piece, which can not be transfer to holey substrate. P = C 0 E 1 ν 2 h a 4 4 + C 1 σ h a 2 0 2 d h + C 2 E h 1 ν a 4 4 d h 3 C. Jiang, et al. Nature Mater. 2004, 3, 721. 10
Sensitive LbL Composites Films 11
Micropattern in Nanomembrane Au NP C. Jiang, et al. Adv. Mater. 2005, 17, 1669. 12
Localized Mechanical Testing 10 μm 30 μm Location λ (μm) E (GPa) With Gold 3.52 4.35 Without Gold 2.76 2.08 Elastic modulus C. M. Stafford, et al. Nature Mater. 2004, 3, 545. A. Nolte, et al. Macromolecules 2005, 38, 5367. C. Jiang, Nano Letters. 2006, 6, 2254. 13
Polymer Chain Behavior 4000 Relative intensity 3500 3000 2500 2000 1500 1100 1200 1300 1400 1500 1600 1700 Raman shift (cm -1 ) 0 5 20 40 60 80 SO3 Raman shift (cm -1 ) 1592 1590 1588 1586 1584 1582 1580 1 2 3 4 5 0 2000 4000 6000 Deflection (nm) SO SO 3 3 C.Jiang, et al. Phys. Rev. Lett. 2005, 95, 115503. Chain-like Au-NP aggregation + spreading of polymer chains Bridging multiple nanoparticles through stretched backbones Outstanding mechanical properties of SA-LbL films 14
Microcavity Arrays Half-inch wafer 64 64 cavity array Over 4000 membranes 600μm 15
Thermal Bulging Heat Cool Heat Cool 400 180 nm/k Deflection (nm) 200 0-200 -400 Experimental Finite Element Analysis 298 299 300 301 Temperature (K) C.Jiang, et al. Chem. Mater. 2006, 18, 2632. Finite Element Analysis 16
Cellulose Nanocrystals 17
Cellulose Nanocrystals 18
Layer by Layer Assembly Gray et.al. Biomacromolecules, 2006, 7, 2522. Lvov et.al. Biomacromolecules 2007, 8, 1987. Kotov et.al. Langmuir 2007, 23, 7901. 19
Preparation of CNCs Hydrolysis of cellulose microfibers with H 2 SO 4 can produce nanoscale cellulose crystals with negative charges on their surface. FPL 20
Cellulose Nanocrystals CNC solution, 0.88 wt% Sample from Forest Product Laboratory, WI Cast film with 88 ppm solution 21
Diameters of the CNCs 5.25±1.21 nm unpublished results 22
Fabrication of CNC Nanofilms Poly(allamine hydrochloride) (PAH) (PAH/CNC) n Sacrificial Layer Acetone 23
PAH/CNC Multilayers (PAH/CNC) 6 88ppm CNC solution 16.7 nm 24
PAH/CNC Multilayers Film thickness (nm) 140 120 100 80 60 40 20 Film thickness Linear Fit of Film thickness Equation y = a + b*x Weight Instrumental Residual Sum of 17.19077 Squares Adj. R-Square 0.98653 r 2 = 0.98 Value Standard Error Film thickness Intercept 13.56454 3.27848 Slope 0.05933 0.0031 Thickness of PAH/CNC bilayer can be tuned 0 0 400 800 1200 1600 2000 CNC Concentration (ppm) 25
PAH/CNC Multilayers (PAH/CNC) n 440ppm CNC solution 140 120 Slope ~8 nm 100 Thickness (nm) 80 60 40 20 0 0 5 10 15 Number of Bilayers 26
PAH/CNC/Au Multilayers (PAH/CNC) 3 PAH/Au(PAH/CNC) 3 PAH 74.53 nm 27
CNC/Au Multilayer Films glass substrate glass substrate 0.16 0.14 1 Layer Au NP 2 Layers Au NP 0.12 glass substrate Absorption 0.10 0.08 0.06 0.04 0.02 [(PAH/CNC) n /Au] 2 0.00 200 300 400 500 600 700 800 Wavelength (nm) 28
SEM of PAH/CNC/Au Multilayers glass substrate 100 nm 29
SERS in Nanomembranes glass substrate 40000 35000 30000 1096 cm 1 glass substrate A.U. (Counts) 25000 20000 15000 10000 5000 1Midlayer of CNC 3Midlayers of CNC 0 0 500 1000 1500 2000 2500 3000 3500 Wavenumber (cm -1 ) 30
PAH/CNC Nanomembranes (PAH/CNC) 15 440ppm CNC solution 120 nm 50 μm 31
PAH/CNC Nanomembranes Buckle image with a 50x objective 3 2 Elastic modulus Film Substrate Ef Vf Es Vs d h GPa MPa μm nm 3.15 0.35 1.8 0.5 5.48 120 C. M. Stafford, et al. Nature Mater. 2004, 3, 545. A. Nolte, et al. Macromolecules 2005, 38, 5367. C. Jiang, Nano Letters. 2006, 6, 2254. 32
Outlook Fabricating robust multilayer ultra-thin membranes with functional cellulose nanocrystals Studying the property-structure relationships of nanomembranes containing cellulose nanocrystals Using SERS properties to design portable sensitive membranes for chemical detection and mechanical sensing. 33
Summary Cellulose nanocrystals are excellent building blocks in assembling composite thin films. Ultrathin Layer-by-Layer multilayer containing cellulose nanocrystals were fabricated and their thickness and properties are tunable. Gold nanoparticles embedded in the CNC multilayer thin films cause SERS. Freely suspended CNC nanomembranes demonstrated excellent mechanical stabilities and potentials in sensing applications. 34
Acknowledgement Dr. Ed Duke SDSMT Mr. Bruce Gray at USD for help on AFM measurement. SEMA group at GaTech for freely-standing nanomembranes. 35
Materials Chemistry @USD 36