I I I I FI I Electrospinning for Scalable Nanofiber Production (CMMI …2015_12_09... · 2015. 12....
Transcript of I I I I FI I Electrospinning for Scalable Nanofiber Production (CMMI …2015_12_09... · 2015. 12....
Multi-Physics Modeling and Experimental Characterization of Needleless
Electrospinning for Scalable Nanofiber Production (CMMI 1234297)
Electrospinning technique is a low-cost, top-down nanofabrication
technique, which enables to produce ultrathin continuous fibers of
natural and synthetic polymers and polymer-derived carbon, metals,
ceramics, and semiconductor materials with the diameters in the
rang of 1 up to 2,000 nm. Electrospun nanofibers are finding broad
advanced structural and multifunctional applications in variable
industrial sectors. Needleless electrospinning is a continuous,
scalable electrospinning method for low-cost, scalable production
of nanofibers. In this project, multiphysics phase-field modeling is
formulated and related experimentation is performed to understand
the electrohydrodynamic process of needleless electrospinning. The
research will benefit the computer-aided electrospinning
engineering (CAEE) in education, research and industrial
applications.
Xiangfa Wu, Department of Mechanical Engineering, North Dakota State University, Fargo, ND
Needle-based vs. Needleless Electrospinning
PAN NFs Ternary PANI/CNTs/CNFsPAN-based CNFs CNT Yarns CNT-grafted CNFs
Core-shell NFs
Selected Nanofiber Applications
• Advanced & functional composites • Multifunctional textiles
• Fuel cells, Li ion batteries, solar cells, • MEMS/NEMS, sensors, flexible actuators;
supercapacitors, & separators • Biomedical applications, drug delivery,
• High-grade multifunctional filters, wound dressing
oil- water separation membranes • Tissue engineering, tissue scaffolding
Nano-cracked Cr-NFs Graphene-CNFs G/PANI-CNFs PANI-coated CNFs
2 2
0
0
Global Free Energy:
1 1[ ( , ) ( ) | | ( , ) | | ]
2 2
Dieletric Constant:
( , ) ( ) (1 )
( )
Flory Huggins Free Energy :
1/ (1 ) ln ln (1 )
de Gennes's Non
rV
solution air
r r r
FH dG
FH
FH
F f c h c c dV
c c c
f f f
f
f m
2
0
local Interface Energy:
1/ 2 | |
Electrostatic Field:
[ ( , ) ] 0
Ginzburg-Langau Equation (Liquid/Gas Interface):
( ) .[ ( ) / | |]
Modified Navier Stokes Equation (Flow Mot
dG
r
c c m
f
c
cv c M c k c c
t
0
ion)
( . ) . :
Cahn Hilliard Equation (Phase Separation-Cavitation):
( ) .[ ( ) / | |]
Numerical Algorithm: Semi-Implicit Spectral Method
c
m
vv v p c
t
v M k c ct
Hybrid Micro/Nanofiber Filtration Media & Control
Microfiber Sample
Interface Toughening & Damage Self-healing
Superhydrophobic & Superoleophilic Nanofibers
for Oil-Water Separation
Nanofiber Applications, Needleless Emulsion-Electrospinning & Multi-Physics Modeling
DCPD-DMF/PAN-
DMF emulsion
Water Droplets
on PS NFs
Water/Oil Contact
Angle on PVDF NFs
Mulitifunctional Fibrous Supercapacitor Electrodes
Core-shell DCPD/PAN
nanofibers
0
100
200
300
400
500
600
700
800
900
0 15
30
45
60
75
90
105
120
135
150
165
180
Ele
ctri
c F
ield
(V
/m)
Phi (degrees)
180˚
Curved90°
CurvedFlat
Jet Initiation & Electrode Span-Angle on DC Electrical Field
0
2231 4 2 20 *
31
0 0
22
*max 31
0
Jet Initiaton (Jet Spacing)
cos( )exp( / )
1
3
Wave number for fastest growth
1
2
mo
m
o o
mo
m
o o
h h kx t
Uh mAhk k k
h h H h
UmAhk
h h H h
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.950
60
70
80
90
100
110
120
130
140Maximum Height vs Time
Time (seconds)
Heig
ht
(Mic
rom
ete
rs)
Dot DefectsLine Defects
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.90
5
10
15
20
25
30
35
40
45
50Minimum Height vs Time
Time (seconds)
Heig
ht (M
icro
me
ters
)
Dot Defects
Line Defects
Jet Growth Rate in Needleless ElectrospinningSurface Dewetting on Jet Initiation
4% 8% 12% 16%4
8
12
16
20
24
0.01"
Cri
tica
l V
olta
ge
(kV
)
PAN Concentration
0.02"
0.04" 0.06"
Collection Distance
(between steel wire & plate)
6.5”
Drop Volume (solution) 2.0 μl
Size of Plate (fiber collector) 12”×12”
Constant Negative Voltage - 2 kV
Diameter of Steel Wires 0.01”, 0.02”,
0.04”, 0.06”
Temperature 20 oC
Solutions PAN/DMF,
PEO/Water
Needleless emulsion spinning for mass production of core-
shell nanofibers
Education & Outreach
• Undergraduate Students: Nicole Reilly (URA), Jeremy Jenniges
(URA), Yesheng Chen (URA), Zheng Fang (URA)
• Native American Tribal College & High-School Students: Shenae
Azure, Darrin Frederick
• Graduate Students: Zhengping Zhou, Meng Yu, Youhao Zhao,
Josh Borglum, Xiao Wang, Zheng Fang
• Two undergraduate senior design groups (6 senior undergraduates)
Collaborations
• Univ. of Illinois-Chicago; North Carolina A & G State Univ.; South
Dakota School of Mines & Tech.; South Dakota State Univ.; Jiangxi
Normal Univ., China
Computational Free-Surface Multi-Jet Initiation
Free-Surface Jet Initiation on Dewetted Surface