Physico-chimie des
Polymères et des
Milieux Dispersés
Photosensitive complexes of hydrophobically
modified polymers, micelles of surfactants
and enzymes.
Juliette RUCHMANN, ESPCI, Paris, France
Macro 2008, Taipei, June 29 - July 4
Stimuli-responsive systems of polymer
and surfactant
Polymer hydrophilic/ hydrophobic
stimuli: pH, T°, light …
protein refolding
sol/gel transition
association polymer / surfactant
multiple applications
understanding of the interaction between
polymer and surfactant
2
Light-stimulated association
h
non invasive and
focused stimuli
 photo-polymer + non responsive surfactant
 macroscopic response to light
 study of physico-chemical parameters
3
Azobenzene-modified polymer
x
O O
HN
100-x
O
HN
(CH2)5
O
x
O O
100-x
O
(CH2)5
NH
O
NH
N
UV : 365 nm
small: 7,500 g/mol
long: 42,000 g/mol or
60,000 g/mol
 amount of modification
x = 1 - 5%
Irradiation
N
Structural parameters
 chain length (Mn)
N
NMR
spectroscopy UV-visible
N
blue : 436 nm
cis
trans
Surfactant
TX 100
42_3.5C6azo
x = 3.5% / Mn=42,000g/mol
O
OH
C8H17
4
Light-responsive complexes
400
200
100
3
in the
dark
1/ mixture =
complexes formation
2/ UV light =
partial
photo-dissociation
mixture
500
42_3.5C6azo
600
300
2
1
700
TX 100
Intensity (A.U.)
Static light scattering
UV
light
Blue
light
0
3/ Blue light =
re-association
reversible photo-association / photo-dissociation
several cycles for hours
J. Ruchmann, S. Fouilloux, C. Tribet, Soft Matter, in press
5
Light-responsive complexes
Black / Blue
trans azobenzene
(100% black / 80% blue)
= hydrophobicity maximum
UV
blue
(365nm)
(436nm)
association with lipophilic core
of the micelles
UV
cis azobenzene (80% UV)
= more polar form
decrease of the affinity for the
micelles
6
Transfer of the azobenzene
from water into the micelles
[azo]BOUND
Δ Abs
A
τ 
[azo]TOT
[azo]TOT
-3
5x10
-1
ΔAbs
1.0
42_3.5C6azo
with TX100
0.5
42_3.5C6azo
0
300
350
400
450
Wavelength (nm)
Abs/[azo] (µM )
Absorbance (D.O.)
(O.D.)
UV visible spectrophotometry
500
4
3
2
1
0
0
0.2
0.4
0.6
0.8
1.0
[TX 100]total (g/L)
bound azobenzene
7
Necklace composition
Electrophoresis
Absorbance
neutral
reference
500
TX100
(neutral)
600
700
complexes
(anionic)
800
Time (s)
900
1000
continuous injection
TX 100bound/polymer (g/g)
binding isotherm
2.5
2.0
1.5
1.0
0.5
0
0
0.2
0.4
0.6
0.8
1.0
[TX 100]free (g/L)
bound surfactants
8
3 regimes of association
-1
Abs/[azo] (µM )
bound
azobenzenes
1 2
4
2.5
3
2.0
3
1.5
2
1.0
1
0.5
0
0
cmc 0.2
0.4
0.6
[TX 100]free (g/L)
tight association
no association
azo bound
TX100 bound
#1
0
0.8
TX 100bound/polymer (g/g)
-3
5x10
bound
surfactants
anti-cooperative
binding
azo bound
TX100 bound
<< 1
9
Electrophoresis
blue irradiation
UV irradiation
TX 100bound/polymer (g/g)
Light-responsive complexes
2.5
2
2.0
3
60% dissociation
1.5
1.0
0.5
0
0
0.2
0.4
0.6
0.8
1.0
[TX 100]free (g/L)
h
black/
blue
42_5C6azo
h
UV
black/
blue
UV
light-response in a large range of compositions
10
Influence of different parameters
TX 100bound/polymer (g/g)
2.5
60% photo-dissociation
2.0
42_5C6azo
2.5
7.5_4C6azo
2.0
1.5
1.5
1.0
1.0
0.5
0
small chain length
30%
photo-dissociation
0.5
0
0.2
0.4
0.6
0.8
1.0
0
0
1% modification
almost no association
2.0
42_1C6azo
1.5
0.5
0.5
0.2
0.4
0.8
1.0
42_5C6azo
1.5
1.0
0
0.6
70% photo-dissociation
2.0
1.0
0
0.4
low ionic strength
2.5
2.5
0.2
0.6
0.8
[TX 100]free (g/L)
1.0
0
0
0.2
0.4
0.6
0.8
[TX 100]free (g/L)
1.0
11
h
Applications
AMPs + protein (BSA)
 photo-responsive
physical gels
h
G. Pouliquen and C. Tribet, Macromolecules, 2006. 39(1), 373-383
AMPs + neutral surfactants
 reversible photo-control of
emulsion
S. Khoukh, et al., Chemphyschem, 2005. 6(10), 2009-2012
J. Ruchmann, S. Fouilloux, C. Tribet, Soft Matter, in press
12
Protein refolding
AMPs + enzyme (BCA)
no aggregation

association
soluble complexes
unfolded
protein
REFOLDING
+
refolded
protein
dissociation
13
Protein refolding
dissociation
+
+
association
quenching
no quenching
Fluorescence
Intensity (A.U.)
50
40
30
20
10
0
0
20
40
60
80
100
Time (min)
14
Physico-chimie des
Polymères et des
Milieux Dispersés
CONCLUSION
photo-control of association/dissociation
with micelles and more generally with
hydrophobic colloids (proteins …)
Acknowledgements
Christophe TRIBET
Agnès PALLIER
Sarah FOUILLOUX
ANR-06-BLAN-0174 and BLAN07-3_190727
French ministery of research
3 regimes
cmc
1
2
3
h
h
h

16
Association with surfactants
Surfactant
TX 100
O
C8 H17
OH
Intensity (a.u.)
1.0
mixture
TX 100
42_3.5C6azo
0.5
0
0.1
1
10
100
1000
Hydrodymanic Radius (nm)
Rh(complexes) ≈ Rh(polymer isolated chains)
Rh(complexes)BLACK ≈ Rh(complexes)UV
 well define complexes
 no aggregation
17
AMP multiple association onto an
hydrophobic cluster.
Kass
TΔSloop + ΔGazo < 0
balance between :
- loop free energy
- free energy of transfer of azobenzene
between water and the micelle
18