Free standing Multilayer Thin Film of Cellulose Nanocrystals

Transcription

1 Free standing Multilayer Thin Film of Cellulose Nanocrystals Chaoyang Jiang Department of Chemistry The University of South Dakota Edmonton, June 25, 2009

2 Cellulose Nanocrystals Nanotechnology R&D Priority for the forest product Nanocomposite thin films by Layer-by-layer assembly. Assembly, Characterizations, & Applications 2

3 Layer by Layer Assembly Spin assisted LbL K. Char, et al. Adv. Mater. 2001, 13, H.-L. Wang, et al. Adv. Mater. 2001, 13, G. Decher, et al. Science 1997, 277, 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

4 Layer by Layer Assembly Rubner and Cohen MIT CEN, 2005, 83(38), 34. Saraf U Nebraska Science, 2006, 312, Kotov, U Michigan Nature Mater. 2003, 2(6),

5 Free standing LbL Films V. Kozlovskaya, et.al., Macromolecules 2005, 38, C.Jiang, et.al. Adv. Mater. 2006, 18, 829. Y. G. Guo, et. al., Adv. Funct. Mater. 2005, 15,

6 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,

7 Free standing LbL Thin Films Sacrificial Layer Acetone Spin-assisted LbL Sacrificial Layer method Freely Suspended LbL nanomembranes 7

8 Composite LbL Nanomembrane C. Jiang et al., Nature Mater , 3(10),

9 Free standing LbL Thin Films ngn n = 3, 5, 7, 9, 11, (PAH-PSS) n PAH/Au/(PAH-PSS) n PAH 2 nm Thickness (nm) C. Jiang, et al. Nature Mater. 2004, 3, Number of PAH-PSS bilayers 9

10 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 ±3.3 9G9, 0.5% SA-LbL ±2.0 9_9, 0% SA-LbL ±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 C 1 σ h a d h + C 2 E h 1 ν a 4 4 d h 3 C. Jiang, et al. Nature Mater. 2004, 3,

11 Sensitive LbL Composites Films 11

12 Micropattern in Nanomembrane Au NP C. Jiang, et al. Adv. Mater. 2005, 17,

13 Localized Mechanical Testing 10 μm 30 μm Location λ (μm) E (GPa) With Gold Without Gold Elastic modulus C. M. Stafford, et al. Nature Mater. 2004, 3, 545. A. Nolte, et al. Macromolecules 2005, 38, C. Jiang, Nano Letters. 2006, 6,

14 Polymer Chain Behavior 4000 Relative intensity Raman shift (cm -1 ) SO3 Raman shift (cm -1 ) Deflection (nm) SO SO 3 3 C.Jiang, et al. Phys. Rev. Lett. 2005, 95, Chain-like Au-NP aggregation + spreading of polymer chains Bridging multiple nanoparticles through stretched backbones Outstanding mechanical properties of SA-LbL films 14

15 Microcavity Arrays Half-inch wafer cavity array Over 4000 membranes 600μm 15

16 Thermal Bulging Heat Cool Heat Cool nm/k Deflection (nm) Experimental Finite Element Analysis Temperature (K) C.Jiang, et al. Chem. Mater. 2006, 18, Finite Element Analysis 16

17 Cellulose Nanocrystals 17

18 Cellulose Nanocrystals 18

19 Layer by Layer Assembly Gray et.al. Biomacromolecules, 2006, 7, Lvov et.al. Biomacromolecules 2007, 8, Kotov et.al. Langmuir 2007, 23,

20 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

21 Cellulose Nanocrystals CNC solution, 0.88 wt% Sample from Forest Product Laboratory, WI Cast film with 88 ppm solution 21

22 Diameters of the CNCs 5.25±1.21 nm unpublished results 22

23 Fabrication of CNC Nanofilms Poly(allamine hydrochloride) (PAH) (PAH/CNC) n Sacrificial Layer Acetone 23

24 PAH/CNC Multilayers (PAH/CNC) 6 88ppm CNC solution 16.7 nm 24

25 PAH/CNC Multilayers Film thickness (nm) Film thickness Linear Fit of Film thickness Equation y = a + b*x Weight Instrumental Residual Sum of Squares Adj. R-Square r 2 = 0.98 Value Standard Error Film thickness Intercept Slope Thickness of PAH/CNC bilayer can be tuned CNC Concentration (ppm) 25

26 PAH/CNC Multilayers (PAH/CNC) n 440ppm CNC solution Slope ~8 nm 100 Thickness (nm) Number of Bilayers 26

27 PAH/CNC/Au Multilayers (PAH/CNC) 3 PAH/Au(PAH/CNC) 3 PAH nm 27

28 CNC/Au Multilayer Films glass substrate glass substrate Layer Au NP 2 Layers Au NP 0.12 glass substrate Absorption [(PAH/CNC) n /Au] Wavelength (nm) 28

29 SEM of PAH/CNC/Au Multilayers glass substrate 100 nm 29

30 SERS in Nanomembranes glass substrate cm 1 glass substrate A.U. (Counts) Midlayer of CNC 3Midlayers of CNC Wavenumber (cm -1 ) 30

31 PAH/CNC Nanomembranes (PAH/CNC) ppm CNC solution 120 nm 50 μm 31

32 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 C. M. Stafford, et al. Nature Mater. 2004, 3, 545. A. Nolte, et al. Macromolecules 2005, 38, C. Jiang, Nano Letters. 2006, 6,

33 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

34 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

35 Acknowledgement Dr. Ed Duke SDSMT Mr. Bruce Gray at USD for help on AFM measurement. SEMA group at GaTech for freely-standing nanomembranes. 35

36 Materials 36