Icam 2009 Soft Actuators H Bridges Nanopores

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

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)

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


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


Electrostatic actuation of integrated artificial cilia
g

Jaap den Toonder, Hans Wilderbeek, Titie Mol, Murray Gillies, Judith de Goede, Wim Talen

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
O CH3 Christiane de Witz, Thijs Bel

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


± 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

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%

Thermal actuation splayed LC network
poly(C3M) / 60 μm

αe
contraction

expansion
αo
500

400

300 αo
200
α (ppm.K-1)

100

0

100
-100

-200
αe
-300
200 250 300 350 400 450
T (K)

Philips Research Laboratories, D.J.Broer, Date(in numbers) Titie Mol

UV light driven
parallel to uniaxial orientation

UV VIS
perpendicular to uniaxial orientation E Z

E

contraction

Z
expansion
Ken Harris, Casper van Oosten

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

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


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,


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


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

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


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


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


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)

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//


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

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


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,

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

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

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

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

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

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

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

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
Carmen Luengo

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

Filling the ion channels with Ba2+

Carmen Luengo

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

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

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.


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)


Icam 2009 Soft Actuators H Bridges Nanopores

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