Nanocomposites of Cellulose For Medical Application Asif Rasheed Lecturer, Department of Chemistry...
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![Page 1: Nanocomposites of Cellulose For Medical Application Asif Rasheed Lecturer, Department of Chemistry University of Wisconsin, Whitewater 800 West Main Street,](https://reader031.fdocuments.us/reader031/viewer/2022020922/56649cc45503460f9498d57e/html5/thumbnails/1.jpg)
Nanocomposites of Cellulose For Medical Application
Asif Rasheed
Lecturer, Department of ChemistryUniversity of Wisconsin, Whitewater
800 West Main Street, Whitewater, WI 53190
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Cellulose:• The most abundant, biodegradable and biocompatible
polymer• Applications include fiber, paper, membrane, polymer and
paint industries• Tissue engineering• Nanocomposites
Strong intra and intermolecular hydrogen bonding hence difficult for processing
H - bonding is reduced by partial replacement of hydroxyl groups, this process involves complex multiple steps and uses toxic chemicals => Conern to Environment
Effect on Nano-filler
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Cellulose Dissolution
• Ionic Liquid: Able to break down H-bonding in biopolymers, hence can dissolve biopolymers e.g. cellulose and silk
Cellulose pulp paper (Grade V-60) from Buckeye Technologies Inc.
Degree of Polymerization ~ 820
Control cellulose film regenerated from ionic liquid
NNH3C
O
O
CH3
CH3
1-ethyl-3-methylimidazolium acetate (EMI acetate)
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1) Composites of cellulose and vapor grown carbon nanofiber (VGCNF) and carbon nanotubes
2) Composites of cellulose and hydroxyapatite (HAP)
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1) Cellulose-CNT Nanocomposite
• Young’s Modulus ~ 1 TPa
• Electrical Conductivity
• ~ 100 times Stronger than Steel at 1/6th of weight
• Thermal Conductivity
SWNT MWNT VGCNF
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Previous Experience with Polyacrylonitrile (PAN)/VGCNF Nanocomposites
2
4
6
8
0 5 10 15 20 25 30 35 40
VGCNF (wt %)
Spec
ific
Mod
ulus
(GPa
.cm
3 /g)
(b)
(a)
(d)
(c)
(e)(A)
(a) Exp.(b) Theo. (0.2 μm)(c) Theo. (1μm)(d) Theo. (10 μm)(e) Theo. (100 μm)
Experimental and theoretical specific modulus of various PAN/VGCNF composite films assuming the modulus of VGCNF to be 50 GPa. (a) Experimental modulus, (b) theoretical modulus assuming VGCNF length to be 0.2 m, (c) 1 m, (d) 10 m and (e) 100 m.
y = 1.291x + 3.4417R2 = 0.9506
-2
-1
0
1
2
3
4
-1.6 -1.2 -0.8 -0.4 0.0
log (V-Vc)
log
(con
duct
ivit
y)
-2
0
2
4
0 0.2 0.4 0.6 0.8
V
log
(con
duct
ivity
)
Electrical conductivity of PAN/VGCNF composite films.
0.0
0.1
0.2
0.3
0.4
0.5
20 40 60 80 100 120 140 160
Temperature (oC)
Tan
δ
(a)
(d)
(b)
(e)
(f)
(a) Control PAN(b) PAN/VGCNF (5 %)(c) PAN/VGCNF (10 %)(d) PAN/VGCNF (20%)(e) PAN/VGCNF (40%)(f) PAN/VGCNF (90 %) (c)
Tan δ (below) as a function of temperature for (a) Control PAN, (b) PAN/5%VGCNF, (c) PAN/10%VGNCF, (d) PAN/20%VGCNF, (e) PAN/40%VGCNF and (f) PAN/90%VGCNF composite films.
Guo, H.; Rasheed, A.; Kumar, Satish J Mater Sci (2008) 43:4363-4369
Mechanical Properties Electrical Conductivity Thermal Stability
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• Electroactive paper• Actuators/sensors• Medical Devices
Cellulose+5%VGCNF
Incorporation of a nano-filler (SWNT, MWNT, VGCNF) into cellulose matrix is expected to
• Enhance tensile strength and tensile modulus
• Impart thermal stability
• Reduce shrinkage (dimensional stability)
• Result in electrical conductivity in the nanocomposite
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2) Cellulose/Hydroxyapatite Nanocomposites
• Hydroxyapatite (HAP) Ca10(PO4)6(OH)2 finds many applications as bio-material
• Filler to replace amputated bone• Coated to promote bone in-growth into prosthetic implants• Cellulose Hydroxyapatite composites have great potential to
be used in bone tissue engineering
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Previous Reports: Cellulose/HAP Composites
• Precipitated on cellulose in-situ from aqueous solution*• Deposition of HAP limited to surface• The process is extensively long (up to ~14 days) to prepare the
composite
*Materials Letters 60 (2006) 1710-1713
Hong, L.; Wang Y. L.; Jia, S. R.; Huang, C. G.; Wan, Y. Z. 2005. Hydroxyapatite/bacterial Cellulose Composites Synthesized via Biomimetic Route. Materials Letter. 60:1710-1713
Current Approach
• Homogenous dispersion of HAP in cellulose matrix
• Fast processing• Composition of composite
can be easily varied
Cellulose+10% HAP Cellulose+60% HAP
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Acknowledgments
• Students (Peter Zastraw, Matthew Magruder, Travis Martin)• Prof. Peter Jacobs (Geology Department, UW-Whitewater)
for XRD• UW-Whitewater for funding• Department of Chemistry, UW-Whitewater
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Cellulose/HAP Composites: XRD
Testing for biocompatibility