1. Photopolymerization of LC networks as
Ph t l i ti f t k
tool for micro- and nanostructuring
micro
Towards Soft Actuators &
Nanoporous Membranes
Dirk J. Broer, C.W.M. Bastiaansen, C.L. van Oosten,
K. D. Harris, J. Lub, C.
K D Harris J Lub C Luengo Gonzalez
Eindhoven University of Technology
Philips Research Laboratories
2. Functional polymers towards medical and
cleantech
l t h
• biosensors • regenerative medicine
• μ-fluidics
fluidics • triggered scaffolds
• MEMS • fiber technology
membranes
b responsive
materials
Nano-
Nano-medicine
Water treatment Energy /
light management
• purification
ifi ti • light capturing & guiding
• targeted filtering • sun tracking
• electro dialysis • reverse electrodialysis
• (blue energy)
Clean Technologies
self-
self-organized micro- and nano features
micro-
Philips Research Laboratories, D.J.Broer, Date(in numbers)
3. Soft Actuators
Courtesy: http://plantsinmotion.bio.indiana.edu
phototropism in sunflower phototropism in plastic
Courtesy: Nikon Microscopy
/Digital Video Gallery
cilia motion in paramecium cilia motion in plastic
Philips Research Laboratories, D.J.Broer, Date(in numbers)
4. Soft Actuators
• Actuating elements, e.g. in microfluidic devices, μ-pumps,
mixers, valves
• (Bio) sensors & controlled drugs release
• Artificial muscles / robotics
• Regenerative medicine
• Energy harvesting and sun tracking
What is needed ?
• Responsive molecules
• Miniaturize structures down to μm level
• Integrate into devices
• Improve on motion figures,
e g as inspired by micro organisms
e.g. micro-organisms
Philips Research Laboratories, D.J.Broer, Date(in numbers)
5. Electrostatic actuation of integrated artificial cilia
g
Jaap den Toonder, Hans Wilderbeek, Titie Mol, Murray Gillies, Judith de Goede, Wim Talen
Philips Research Laboratories, D.J.Broer, Date(in numbers)
6. Fabrication of electrostatic elements
800 μm 100 μm
glass (embedded electrodes not shown) develop acrylate in alkaline solution
+ patterned Al (100 nm)
add 10 nm chromium layer etch Cr in cerium ammonium nitrate
add 10 μm acrylate mix etch Al in phosphoric acid
photopolymerized through mask CH3
O CH3 CH2 C
n
O C C CH2 C O
CH2 O CH3 O
CH3 CH2 C CH2 O C C CH2 CH2
CH2 induced stresses make the elements curl
O C C CH2
Philips Research Laboratories, D.J.Broer, Date(in numbers)
O CH3 Christiane de Witz, Thijs Bel
7. Photopolymerization of self-organizing reactive
liquid crystals
liquid crystal with reactive end groups
O
O
O
O O
O O
O O
O
hν
bottom-up / top-down
nano/micro structuring
aligned LC monomer
Philips Research Laboratories, D.J.Broer, Date(in numbers)
8. ± 25 yrs experience: LC networks are presently used to
improve LCDs on viewing angle, contrast and brightness
angle
hν
based on solid coatings and thin films with
anisotropic optical properties
e.g. Δn = n// - n⊥= 0.05 to 0.25
Philips Research Laboratories, D.J.Broer, Date(in numbers)
9. Liquid Crystal Actuators
O
O
O
O O
O O
O O
O
hν
LC networks
• Can be patterned, e.g.
by lithographic means
• Can be made responsive
by orientation gradients
• High modulus - 1GPa
• Large work potential!
despite small deformations
~ 2%
Philips Research Laboratories, D.J.Broer, Date(in numbers)
11. UV light driven
parallel to uniaxial orientation
UV VIS
perpendicular to uniaxial orientation E Z
E
contraction
Z
expansion
Ken Harris, Casper van Oosten
Philips Research Laboratories, D.J.Broer, Date(in numbers)
12. Liquid crystal network UV-actuator
q y
Specific internal work comparison
Modulus Work density*
Actuator comparison Strain (MPa) (kJ/m3)
LC network UV actuator 1,5% 1000 56
1
LC elastomer UV actuator 13% 1 4
2
Thermal LC elastomer 50% 1 50
2
Skeletal Muscle 20% 40 80
*W = ¼ ε2E
1. M. Camacho-Lopez et al., Nat. Mater., vol. 3, 2004, 307-310
2.
2 J.Madden al., J.
J Madden et al J Of Oceanic Eng 29 (3) July 2004 706-728
Eng., (3), 2004, 706 728
Casper van Oosten
Philips Research Laboratories, D.J.Broer, Date(in numbers)
13. Optimized X-link density for fast response
UV
0s 8s 16 s 24 s 32 s
VIS
0s 4s 8s 12 s 20 s
poly(5.5wt-%A6MA/C6M)
O
H2C
O (CH2)6 O O
+ 48% O (CH2)5 CH3
O
0s 0.08 s 0.16 s 0.24 s 0.32 s
Ken Harris, Casper van Oosten
Philips Research Laboratories, D.J.Broer, Date(in numbers)
14. Bending also possible in uniaxial LC networks
with gradient i UV i t
ith di t in intensity
it
gradient in
deformation
gradient in
UV intensity
Light tracking
Tabiryan
Under study: Beam Engineering
efficient light harvesting Bunning group, Air Force
for solar energy? Lab Dayton, USA
O ti Express, 2005 13 7442
Optics E 2005, 13,
Philips Research Laboratories, D.J.Broer, Date(in numbers)
15. Back bending of uniaxial films in UV
gradient films
• time delayed azo response
• photobleaching
• bending depends on X-link Acknowledge Mark Warner
density
• X-link gradient by
X link
polymerization-induced diffusion
UV light
Side
Sid A
Fast reacting molecules Intensity
gradient
Slower reacting molecules
Substrate Side B
Philips Research Laboratories, D.J.Broer, Date(in numbers)
16. Device integrated photoresponsive elements:
• structured by inkjet technology
• multi-color responsive elements
multi-
160
140
contraction
120
100
Angle
80
(degr)
60
40
20
expansion
p
0
0 500 1000 1500 2000
I (mW/cm2)
Casper van Oosten
Philips Research Laboratories, D.J.Broer, Date(in numbers)
17. Next steps at TU/e group
Reverse function and
employ microstructures f energy harvesting:
l i t t for h ti
E.g.
• polymer flaps with oriented dipoles
(ferroelectrics)
• electrodes top and bottom
Energy from:
• breeze
• motion (vibration e.g. in building)
• sound
First estimates: 0.1 to 10 W.m-2 large area technologies
Philips Research Laboratories, D.J.Broer, Date(in numbers)
18. Reduction of order parameter + gradients in director
profile driving force for geometry changes
Mechanisms for Order Reduction / triggers
– Temperature variation
– Breaking order by isomerization under radiation
– Breaking chemical bonds, chemical reactions (pH)
– Solvent swelling/deswelling
Ken Harris, Casper van Oosten
Philips Research Laboratories, D.J.Broer, Date(in numbers)
19. Anisotropic hydrogels: H-bridged LC networks
O HO O
O
O O
O
O OH O
L. Strezelecki, L. Liebert, Bull. Soc. Chim. France, 597 (1973) & 605 (1973)
hν
Cr 92 SmA 110 I
Ken Harris, Casper van Oosten
Philips Research Laboratories, D.J.Broer, Date(in numbers)
20. Anisotropic hydrogels: H-bridged LC networks
OBA n = 3,5,6 (1:1:1)
C6M
140
120
hν
100
Temperatu ( C)
o
80 70 -105 oC processing window
ure
60 Nematic
N ti 12 wt% C6M
//
40
Smectic
20
Cryst
0
Cryst ⊥
-20
0 20 40 60 80 100
Composition (wt% C6M)
Ken Harris, Casper van Oosten
Philips Research Laboratories, D.J.Broer, Date(in numbers)
21. Anisotropic swelling in alkaline buffer solution
O HO OH- O O-
OH O H+ O- O
L⊥
L//
%)
ansion (%
ΔL ⊥ ΔL //
>
L⊥ L //
L⊥+ΔL Expa
⊥ Time (min)
Ti ( i )
L//+ΔL//
Ken Harris, Casper van Oosten
Philips Research Laboratories, D.J.Broer, Date(in numbers)
22. Chemical Actuation – pH
• Twisted configuration
g
• poly(nOBA/12%C6M)
• 18μm thick
• pH controlled with NaOH
and acetic acid
slow
expansion
fast
expansion
• Motion occurs over limited pH range at pH~11
• Deformation i reversible
D f ti is ibl
Ken Harris, Casper van Oosten
Philips Research Laboratories, D.J.Broer, Date(in numbers)
23. Activate by KOH dip – deactivate in acetic acid
polymer chains
L
activate deactivateo
base acid
Challenges:
• water driven motor (with Peter Palffy-Muhoray)
• (bio) molecular recognition:
-NH2, CO2, O2 together with Sijbesma -TU/e
uptake of agent
molecules
Lt
Ken Harris, Casper van Oosten
Philips Research Laboratories, D.J.Broer, Date(in numbers)
24. Application of a hydrogel soft actuator: Wrapping of
eukaryotic cells
Objectives:
• To develop cell delivery technique
• Potential to combine different cell
population
Status:
• Experiments withA 431, human
withA-431,
carcinoma epidermoid cells
37 25 oC
25 37 oC
Sara Pedrón-Haba, Emiel Peeters,
Philips Research Laboratories, D.J.Broer, Date(in numbers)
25. Smectic hydrogen-bridged networks towards
nano-channels
h l
OBA n = 3 5 6 (1:1:1)
3,5,6
C6M
140
120
100
Temperatu (oC)
80
ure
60 Nematic
N ti
40
Smectic
20
Cryst
0
Cryst
-20
0 20 40 60 80 100
Composition (wt% C6M)
Carmen Luengo
Philips Research Laboratories, D.J.Broer, Date(in numbers)
26. X-linked smectic hydrogen-bridged LC networks
hydrogen-
O
O HO ~19 Å O
O O
O
O OH O
O O
O
O ~42 Å
42 O O
O
O O
O
monomer / 104oC polymer / 104oC polymer / RT
hν
h cool
polymerization down
26Å 27Å
Å
43Å 30Å 31Å
Carmen Luengo
Philips Research Laboratories, D.J.Broer, Date(in numbers)
27. X-linked smectic hydrogen-bridged LC networks
hydrogen-
O HO O
O
O O
O
O OH O
O O
O
O O O
O
O O
O
0.50
ν H-bridges
(C=O)
only H bridges / RT
sorbance
0.40 H-bonded
ν (C=O) δ (C=C)
0.30 acrylate
Abs
0.20
0.10
0.00
0 00
1900 1850 1800 1750 1700 1650 1600 1550 1500 1450 1400 1350 1300
Wavenumber
O
free C
hν OH
would have ν(C=O)
( )
at ~ 1730 cm-1
Carmen Luengo
Philips Research Laboratories, D.J.Broer, Date(in numbers)
28. Covalent X-link bridges conserve order
X-
during heat cycling
O HO Δ
Δ O HO
OH O OH O
linear / RT linear / >200oC linear / RT
heat cool
linear
X-linked (10w%) / RT X-linked / >200oC X-linked / RT
X-linked
X linked
heat cool
O O
O
O O O
O
O O
O
Conclusion: Alignment is recovered by presence of covalent X-links
Philips Research Laboratories, D.J.Broer, Date(in numbers)
29. Covalent X-link bridges conserve order
X-
during heat cycling
O HO Δ
Δ O HO
OH O OH O
600
500
400
Birefringence:
Δ
dΔ n
300 planar oriented samples
between rubbed polyimide
200
glass plates
100
0
0 50 100 150 200 250
o
Temperature ( C)
Carmen Luengo
Philips Research Laboratories, D.J.Broer, Date(in numbers)
30. Breaking the H-bridges at high pH
H-
NH4+
O HO NH44OH
NH OH O O-
OH O H++
H O- NH + O
4
0.14 184-10% om
079h eotropicfilm on w ou solu
-am ia, ith t tion 0.45 184-10% om
079h eotropicfilm on after addin solu
-am ia, g tion symmetric CO2
Antisymmetric CO2
1382.1
0.40
1675.6
0.12
0.35
0.10
0.30
1531.8
Absorbance
Absorbance
0.08 0.25
0.20
0.06
0.15
0.04
0.10
0.02
0.05
005
1900 1850 1800 1750 1700 1650 1600 1550 1500 1450 1400 1350 1300 1 1900 1850 1800 1750 1700 1650 1600 1550 1500 1450 1400 1350 1300 1
W enum
av ber W enum
av ber
• Hi h order of th l
High d f the layers
• Reduced order within the layer
Carmen Luengo
Philips Research Laboratories, D.J.Broer, Date(in numbers)
31. Breaking the H-bridges at high pH
H-
NH4+
O HO NH44OH
NH OH O O-
OH O H++
H O- NH + O
4
27Å NH4OH
31Å 34Å
• Hi h order of th l
High d f the layers
• Reduced order within the layer
Carmen Luengo
Philips Research Laboratories, D.J.Broer, Date(in numbers)
32. Opening of the network at high pH
NH4+
O HO NH44OH
NH OH O O-
OH O H++
H O- NH + O
4
27Å NH4OH
31Å 34Å
800
• Well-spaced p
p porous p y
polymer layer
y
600
structure with ionic interior
• Estimated pore size ~ 1 nm when
dΔ n
400
molecular rods adapt random order
• Anisotropic ‘in-plane’ pore dimensions
200 measured pKa • Upon electrolyte/water uptake:
at monomer in-plane swelling
0
0 4 8 12
pH
Philips Research Laboratories, D.J.Broer, Date(in numbers)
Carmen Luengo
33. Opening of the network at high pH
ClO4-
N
H2N O N CH3
CH3
reddish/colorless blue
2 0.04
t = 0 / pH>11 pH < 10.1-11.1
NH4OH solution
1.5 0.03
nce
Absorban
1 0.02
t = 24 hrs
0.5 0.01
0 0
300 400 500 600 700 800 900
pH ~7
Wavelength (nm) Carmen Luengo
Philips Research Laboratories, D.J.Broer, Date(in numbers)
34. Filling the ion channels with Ba2+
Philips Research Laboratories, D.J.Broer, Date(in numbers)
Carmen Luengo
35. Insertion of dipyridines in monomeric state
influences the pore sizes
Forms a stable smectic complex:
~47 Å O O
O O O (CH2)6 O
O (CH2)6 O N HO
OH N
O ( SmX 110 I)
O
O O
O O O
O
O
O
~42 Å
43Å 43Å 43Å
polymerization NH4OH
at 110 oC
cool to RT
Estimated (XRD) pore sizes:
5 to 9 nm
Carmen Luengo
Philips Research Laboratories, D.J.Broer, Date(in numbers)
36. Applications being studied
easy integration in
nanolithography, e.g. μ-fluidic devices
for nanoelectronics
separation, e.g
for water desalination
clad inner surfaces,
e.g.
e g for catalysis
templated polymerization,
e.g.
e g for anisotropic
conduction
ion conduction
e.g. for batteries ion l ti
i selection, e.g.
for blue energy
Philips Research Laboratories, D.J.Broer, Date(in numbers)
37. Summary
• Engineering toolbox for top down/bottom up polymer network structuring
• Top down: lithography/holography/printing mostly in the μm range;
occasionally down to 50 nm
• Bottom-up: control over molecular order structured down to nm level
• Applications:
Optics, mechanics, electronics, fluidics, separation, biosensors,
…………………medical, clean technologies.
Philips Research Laboratories, D.J.Broer, Date(in numbers)
38. With thanks to:
The PICT group at TU/e The Biomolecular Engineering
• Cees Bastiaansen - Associate Prof. group at Philips Research
• Dick de Boer - Industrial Fellow (10%) • Johan Lub
• Michael Debije - Postdoc • Emiel Peeters
• Ko Hermans - PhD student • Roel Penterman
• Carmen Luengo-Gonzalez - PhD student • Ralph Kurt
• Xiaoran Li - PhD student (1/9-08)
(1/9 08) • David Halter
• Casper van Oosten - PhD student • Christiane de Witz
• Katherine Pacheco Morillo - Postdoc • Titie Mol
• Helena Plasschaert - PhD student • Hans Wilderbeek
• An Prenen - PhD student • Thijs Bel
Thij B l
• Shufen Tjoi - PhD student • Jaap den Toonder
• Joost Valeton - PhD student • Auke van Dijken
• Shabnam Zakerhamidi - Staff • Harry Wondergem
Just left • Chamindie Punyadeera
• Chris van Heesch - finished PhD • Ron van Lieshout
(now Philips Research Eindhoven)
• Judith de Goede
• Charlotte Kjellander - finished PhD
• Murray Gillies
(now TNO Holst Eindhoven)
• Blanca Serrano-Ramon - finished PhD
• Ken Harris - former postdoc
(now NINT - Edmonton)
Philips Research Laboratories, D.J.Broer, Date(in numbers)