Transcript Investigation of aggregation in micelle solution of

Investigation of aggregation in
surfactants solutions by the SANS
method
Dominika Pawcenis
Faculty of Chemistry,
University of Wroclaw, Poland
Frank Laboratory of Neutron Physics
Small – Angle Neutron Scattering Team
Supervisor: A. Rajewska
Purpose of the project
• Investigation of shape and size of micelles in
mixture systems of surfactants solutions
(nonionic + ionic) at different temperatures.
• Investigation of shape and size of micelles in
nonionic surfactant solutions only.
2010 Student Practice in JINR Field of
Research
2
Surfactants
• SURFace ACTive AgeNT
• Soap
• Detergents (anionic, cationic, zwitterionic,
nonionic)
Hydrophobic “tail” and hydrophilic “head”
2010 Student Practice in JINR Field of
Research
3
Micelles – structure of aggregations
2010 Student Practice in JINR Field of
Research
4
Self – assembly
P≈1
P<1/3
P<1/2
Packing Parameter
P= V/aL
• a – Head group cross-sectional
area
• l – Length of tail
• V – Volume of tail
17 July 2015
2010 Student Practice in JINR Field of
Research
5
Synergistic effect in mixtures of
nonionic and ionic surfactants
• It was observed that for mixtures of nonionic
and ionic surfactant solutions (in water or in
heavy water) CMC of mixture system is
smaller than each of these two surfactants (in
water or heavy water).
2010 Student Practice in JINR Field of
Research
6
Thermodynamics of micellization
nS 
 M n
[M n ]
K n
[S ]
Ct  [ S ]  nK[ S ]n
 G  RT ln K
 G  RT (ln[M n ]  n ln[S ])
 G RT
 G 

ln[M n ]  RT ln[S ]
n
n
 G 0  RT ln[S ]
0
[ S ]  CMC
CMC – Critical Micelle
Concentration
G  RT ln CMC
2010 Student Practice in JINR Field of
Research
7
Chemicals used in mixed system
C16TABr – cetyltrimethylammonium bromide C16H33N(CH3)3Br cationic
Triton X-100 – C14H22O(C2H4O)n nonionic
n=10
p-(1,1,3,3-tetramethyl )poly(oxyethylene)
17 July 2015
2010 Student Practice in JINR Field of
Research
8
Information from SANS
•
•
•
•
•
polymers
biomolecules
Size
Shape
Molecular weight
nanomaterials
surfactants
Interaction distance
Self-Assembly
Magnetic
liquids - 8˚
0.008˚
2010 Student Practice in JINR Field of
Research
9
SANS fundamentals
Q
Θ/2
Neutron source
sample
I (Q)  A  P(Q)  S (Q)
  ( r )e
P(Q) 
iQr
dr
3
2
  (r )dr
detector
2
3
Atomic
I(Q)
nucleus
Molar weight
b [fm]
– intensity
[g/mol]
A  n 
A – const.
1H
- 3.741 form factor1
exam ple:
P(Q) – normalized
H – structure
+ 6.674factor
2
 D 2O  (1.1 / 20) N A (0.5805 2  0.6674)  1012 cm  2 2S(Q)
(for dilute solutions S=1)
C
+ 6.646
12
1.1 – heavy water density [g/ml]
n – number
of density
20 – molecular weight of D2O
ν – volume+ of
particle
N
9.362
14
NA – Avogadro`s number 6.02·1023 mol-1
∆ρ – difference of length density
0.5805, 0.6674 – scattering length of oxygen and
O scattering
+ 5.805
16
deuterium
Q – scattering
vector
+ 6.795
173
2010 Student Practice in JINR Field of Br
2
17 July 2015
2
Research
10
Scattering length density
2010 Student Practice in JINR Field of
Research
11
The scattering vector
The modulus of the resultant between the
incident, ki, and scattered, ks, wavevectors,
given by:
Neutron source
ks
ki
sample
Q  Q  k s  ki 
17 July 2015
4n

detector
sin(  / 2)
2010 Student Practice in JINR Field of
Research
12
2010 Student Practice in JINR Field of
Research
13
Differential cross – section
• Contains all the information on the shape, size
and interactions of the scattering bodies in the
sample.

2
2
(Q)  N pV p ( ) P(Q) S (Q)  Binc

Np – number concentration of scattering bodies
Vp2 – square of the volume of scattering body
∆σ2 – square of the difference in neutron scattering length densities
Q – the modulus of the scattering vector
Binc – the isotropic incoherent background signal
17 July 2015
2010 Student Practice in JINR Field of
Research
14
2010 Student Practice in JINR Field of
Research
15
IBR – 2
Fast Pulsed Reactor
Main movable
reflector
Core, PuO2
Reactor vessel
Stationary
reflector
Additional
movable
reflector
moderator
17 July 2015
2010 Student Practice in JINR Field of
Research
16
Spectrometer YuMO
1 – two reflectors
2 – zone of reactor with moderator
3 – chopper
4 – first collimator
5 – vacuum tube
6 – second collimator
7 – thermostate
8 – samples table and holder
for samples
9 – goniometr
10 – V-standard
11 – V-standard
12 - ring-wire detector
13 – position-sensitive detector “Volga”
14 – direct beam detector 2010 Student Practice in JINR Field of
17 July 2015
Research
17
Main parameters of YuMO instrument Parameters
Value
Flux on the sample (thermal neutrons) 107 – 4x107 n/(s cm2) [1]
# - without cold moderator
Used wavelength 0.5 Å to 8 Å #
@ -could be easy changed to decreasing
Q-range 7x10-3 – 0.5 Å-1
* - only for estimation (Radii of giration from
Dynamic Q-range qmax/qmin up to 100
200 Å - to 10 Å - Angstroem)
Specific features Two detectors system [2,3], central hole detectors
^ - in basic configuration of instrument
Size range of object 500 – 10 Å
** - in special box, using nonstandard devices
Intensity (absolute units -minimal levels) 0.01 cm-1
+ - for estimation only
Calibration standard Vanadium during the experiment [4]
*** - simultaneosly in standard cassete with
Size of beam on the sample 8 – 22 mm2 @
Hellma
Collimation system Axial
Detectors He3 -fulfiled, home made preparation, 8 independent wires [5]
Detector (direct beam) 6Li-convertor (home made preparation)
Condition of sample In special box in air
Q-resolution low, 5-20%
Temperature range -50oC -+130oC ^ (Lauda)
Temperature range 700 oC ** (Evrotherm)
Number of computer controlled samples 14
***
Background level 0.03 – 0.2 cm-1
Mean time of measurements for one sample 1 h
+
Frequency of pulse repetition 5 Hz
Electronic system VME
The instrument control software complex SONIX [6]
Controlling parameters Starts (time of experiments), power, vandium standard position , samples position, samples box
temperature, vacuum in detectors tube.
Data treatment SAS, Fitter [7-9]
2010 Student Practice in JINR Field of
Research
18
Holder for samples
2010 Student Practice in JINR Field of
Research
19
•
•
•
•
PCG v. 2.0 program
Author: Prof. Glatter Otto
University of Graz, Austria
PCG v. 2.0 consists of 6 pieces (GIFT, Length
Profile, Mini Viewer, Multibody, PDH, Rasmol
PCG)
element of this program is GIFT. GIFT`s
element is IFT.
With IFT program p(r) vs r was computed
With GIFT program S(Q) can be computed
2010 Student Practice in JINR Field of
Research
20
Experiment for mixture system
conditions
• Investigation of influence of composition of
micelle solution on the aggregation;
• Mixtures of dilute solutions of Triton X -100
and C16TABr in ratio:
No
Triton
X-100
C16TABr
1
1
1
2
2
1
3
3
1
at temperatures: 300, 500, 700, 900 C for each set
17 July 2015
2010 Student Practice in JINR Field of
Research
21
Results for TX-100/C16TABr mixtures
+ D2O
p(r) vs r for ratio 1:1
at temp 300 C – 900 C
Experimental data for ratio
1:1 at temp. 300 C – 900 C
0.14
3.5
n1_30
n1_t50
n1_t70
n1_t90
3.0
n1_30
n1_t50
n1_t70
n1_t90
0.12
0.10
2.0
0.08
p(r)
d(q)/d, cm
-1
2.5
1.5
0.06
1.0
0.04
0.5
0.02
0.0
0.00
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0
-1
4
6
8
10
r[nm]
q[A ]
17 July 2015
2
2010 Student Practice in JINR Field of
Research
22
Results for TX-100/C16TABr mixtures
+ D2O
Experimental data for ratio
2:1 at 300 C – 900 C
p(r) vs r for ratio 2:1
at temp 300 C – 900 C
5
n2_30
n2_t50
n2_t70
n2_t90
4
n2_30
n2_t50
n2_t70
n2_t90
0.20
3
p(r)
d(q)/d, cm
-1
0.15
0.10
2
0.05
1
0
0.00
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0
-1
4
6
8
10
r[nm]
q [A ]
17 July 2015
2
2010 Student Practice in JINR Field of
Research
23
Results for TX-100/C16TABr mixtures
+ D2O
p(r) vs r for ratio 3:1
at temp 300 C – 900 C
Experimental data for ratio
3:1 at 300 C – 900 C
8
0.35
n3_30
n3_t50
n3_t70
n3_t90
7
0.25
5
0.20
4
p(r)
d(q)/d,cm
-1
6
n3_30
n3_t50
n3_t70
n3_t90
0.30
0.15
3
2
0.10
1
0.05
0
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.00
0
-1
q[A ]
17 July 2015
2
4
6
8
10
r[nm]
2010 Student Practice in JINR Field of
Research
24
Mixture systems TX-100/C16TABr + D2O
for different ratio at temp. 300 C …
6.5
n1_30
n2_30
n3_30
6.0
5.5
4.5
4.0
3.5
p(r)
d(q)/d,cm
-1
5.0
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.34
0.32
0.30
0.28
0.26
0.24
0.22
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
n1_30
n2_30
n3_30
0
-1
4
6
8
10
r[nm]
q[A ]
17 July 2015
2
2010 Student Practice in JINR Field of
Research
25
and 700 C
7.5
7.0
n1_t70
n2_t70
n3_t70
6.5
5.5
5.0
4.5
4.0
p(r)
d(q)/d, cm
-1
6.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.34
0.32
0.30
0.28
0.26
0.24
0.22
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
n1_t70
n2_t70
n3_t70
0
-1
4
6
8
10
r[nm]
q[A ]
17 July 2015
2
2010 Student Practice in JINR Field of
Research
26
Nonionic surfactant heptaethylene glycol
monotetradecyl ether (C14E7) in dilute heavy water
solutions. Influence of concentration and temperature
on aggregation in solutions
• Nonionic classic surfactant C14E7 ( heptaethylene glycol
monotetradecyl ether ) in water solution was investigated for
temperatures below the cloud point for seven temperatures
6o, 10o, 15o, 20o, 25o, 30o and 35o C in dilute solutions for
concentrations: c1= 0.17%, c2 = 0.5%
with small-angle
neutron scattering (SANS) method.
hydrophobic tail
hydrophilic head
2010 Student Practice in JINR Field of
Research
27
CiEj
The surfactant studies have included
C14E7 where “C” and “E” refer to
alkyl(CH)x and ethoxylate(CH2CH2O)
units in the conventional shorthand
notation.
NONIONIC SURFACTANTS
Nonionic surfactants such as oligo( oxyyethylene)-n-alkyl
ether ( abbreviated as CiEj ) show a rich phase behaviour in
aqueous mixtures. At very low surfactant concentrations the
surfactant dissolves in the form of unimers. With an increase
in the surfactant concentration the temperature dependent
critical micelle concentration ( cmc ) is passed and the surfactant
molecules form mostly globular micelles at least at low temperatures.
A common feature of these surfactants in mixtures with water
is an upper miscibility gap with a lower critical point in the
temperature – composition diagram.
Above the so-called cloud curve the solutions first become very
turbid and then phase separate into two micellar solutions of
extremely different surfactant contents. The position of the critical
point depends on the overall chain length of the amphiphile and
hydrophilic-lipophilic balance. The understanding of the binary
phase behaviour and structural properties is central for understanding
of ternary mixtures with oil ( microemulsions ).
2010 Student Practice in JINR Field of
Research
29
Results for C14E7 + D2O
Concentration 0.17 %
0.016
10
C14E7+D2O
d(Q)/d, cm
-1
1
0.1
c=0.17%
o
6C
o
10 C
o
15 C
o
20 C
o
25 C
0.012
0.010
p (r)
c=0.17%
o
6C
o
10 C
o
15 C
o
20 C
o
25 C
o
30 C
o
35 C
C14E7+D2O
0.014
0.008
0.006
0.01
0.004
0.002
1E-3
0.000
0.01
0.1
0
2
4
6
8
10
12
14
16
18
20
r [nm]
-1
Q [A ]
2010 Student Practice in JINR Field of
Research
30
Results for C14E7 + D2O
Concentration 0.5 %
0.045
C14E7+D2O
c=0.5%
o
6 C
o
10 C
o
15 C
o
20 C
o
25 C
o
30 C
o
35 C
d(Q)/d, cm
-1
1
0.1
C14E7+D2O
0.040
c=0.5%
o
6C
o
10 C
o
15 C
o
20 C
o
25 C
0.035
0.030
p (r)
10
0.025
0.020
0.015
0.01
0.010
0.005
1E-3
0.000
0.01
0.1
0
2
4
-1
Q [A ]
6
8
10
12
14
16
18
20
22
r [nm]
2010 Student Practice in JINR Field of
Research
31
Shape of micelles
2010 Student Practice in JINR Field of
Research
32
Shape of micelles
2010 Student Practice in JINR Field of
Research
33
Conclusions
• Synergistic effect in mixed systems TX-100/C16TABr we observed. At the
same temperature but for different compositions of solutions the shift of
maximum of intensity of scattering neutrons to bigger values of q
wavescattering vector –show us that the size of micelles is smallest for
ratio 3:1 according relation below q ~ 1/D
where
q – wavescattering vector
D – size of object ( for us micelle )
• With increasing ratio of Triton X-100 to C16TABr and temperature mixture
system changes properties from nonionic to ionic – like.
• Shape of micelles – for lowest temperature and ratio 1:1 near spherical
(with r = 3 nm) than biaxial ellipsoids ( with short axis a = 6.5 nm and long
axis b = 3 nm )
17 July 2015
2010 Student Practice in JINR Field of
Research
34
Conclusions
• For nonionic surfactants with growing temperature size of
micelles increases;
• Shape of micelles of nonionic surfactant C14E7 for
concentration 0.17% and 0.5% for temperature range 6˚ - 35˚C
is cylindrical;
• Table for concentration
0.17%
0.5%
r [nm]
L [nm]
T [˚C]
r [nm]
L [nm]
T [˚C]
3
3.5
6
3
3
6
3
8
10
4
8
10
3.5
9.5
15
4.2
9.8
15
3.5
12.5
20
5
12
20
4
114
25
5
16
25
2010 Student Practice in JINR Field of
Research
35
Special thanks:
Aldona Rajewska
Ewa Chmielowska
Roman Zawodny
Władysław Chmielowski
2010 Student Practice in JINR Field of
Research
36
Literature
•
•
•
•
•
•
•
•
Structure Analysis by Small-Angle X-Ray and Neutron Scattering, L. A. Fegin, D. I. Svergun,
New York: Plenum Press, pp 33, 1988
Small Angle X – ray Scattering, O. Glatter, O. Kratky, Academic Press, 1982
Structure and interaction in dense colloidal systems: evaluation of scattering data by the
generalized indirect Fourier transformation metohod, G. Fritz, O. Glatter, J. Phys.: Condens.
Matter 2006, 18, 2403 - 2419
Study of Mixed Micelles with Varying Temperature by Small-Angle Neutron Scattering, V. M.
Garamus, Langmuir 1997, 13, 6388 – 6392
Micelle Formation and the Hydrophobic Effect, L. Maibaum, A. R. Dinner, D. Chandler, J. Phys.
Chem. B 2004, 108, 6778 – 6781
Dubna Pulsed Neutron Resources, A. V. Belushkin, Neutron News, Vol. 16, Number 3, 2005
Small-Angle Scattering of X-rays, A. Guinier, G. Fournet, John Wiley & Sons Inc.,New York
1955
Two-Detector System for Small- Angle Neutron Scattering Instrument, A. I. Kuklin, A. Kh.
Islamov, V. I. Gordeliy, Scientific Reviews, 2005, 16, 16-18
17 July 2015
2010 Student Practice in JINR Field of
Research
37
Indirect Fourier Transformation

 v (q )  4 
 v (r )
sin qr
dr
qr
0
N
p (r )   cv v (r )
v 1
N
I (q )   cv v
v 1
N
~
I exp (q )  I (q )   cv  v (q )
v 1
L
1
M
M

( I exp (qi )  v 1 cv  v (qi ) 2
i 1
N
 2 (qi )
N 1
N c   (cv 1  cv ) 2
v 1
( L  N c )  min
2010 Student Practice in JINR Field of
Research
38
From scattering amplitudes to
scattering intensities
2010 Student Practice in JINR Field of
Research
39
Spatially Averaged Intensity
2010 Student Practice in JINR Field of
Research
40

The q–dependent scattering intensity I (q )is the complex
square of the scattering amplitude F (q ), which is the Fourier
transform of the scattering length density difference
describing the scattering particle in real space. In solution 
scattering one measures the spatial average of these  (r )
functions, and we finally have:

sin qr
I (q)  4  p(r )
dr
qr
0
Where p(r) is the pair distance distribution function (PDDF) of
the particle:
2
~
p( r )  r  ( r )
2
2010 Student Practice in JINR Field of
Research
41
2
~
 (r )
is the convolution square (spatial
correlation function) of ∆ρ(r) averaged over
all orientations in space. The functional
form of I(q) or p(r) can be used to
determine the shape and the internal
structure of the scattering object .
2010 Student Practice in JINR Field of
Research
42