osmotic pressure is the key

Cours de chimie séparative M3/D1-D2
Master CSMP ED 459
Session 2013-2014 :
Osmotic pressure :
Diving in the sea : take into account pressure versus
depth !
Diving in nano-world: osmotic pressure is the key
[email protected]
14/12/2013
Cours de chimie séparative Master CSMP ED 459
Session 2013-2014 :
- 
- 
- 
Osmotic pressure :
General meaning
Historic approach : Jean Perrin
Osmotic pressure in practical applications
Osmotic presure to investigate LRI : EOS
Jean-francois.dufrê[email protected]
7/12/2013
II
P+ΔP
I
P
Osmotic pressure : derivative of free energy vs volume
Controlled humidity, membrane or capillary rise
HR fixée
H.R. = P/P0 = asolvant
X X X
Dispersion
Solution sursaturée
de sel
(ou tonomètres…)
π =−
k.T
.ln$&%asolvant ')(
0
Vsolvant
dispersion
membrane
solvant
capteur de P
P = Patm + ms.g.h
h
P' = Patm
Π = P-P’ = ρs.g.h
réservoir
solution
Dessicating salt set : the poor man’s method
The osmotic stress* method , even without membrane
I
II
-
réservoir
*alias « pressostat »
Parsegian, ….Brotons G. et al., Langmuir (2003)…
Equation of state : EOS ( P, T; c)
Van’t Hoff equation (1903) >> Van de Waals fluid
π
=1
ρ.k.T
Carnahan-Starling dispersion of spheres ( φ= frac. Vol.)
2
3
π
1+φ +φ −φ
=
3
ρ.k.T
(1−φ )
Ideal situation: theta solvent
Possible atmospheres ( Laplace>van’t Hoff)
Mgh
P = P0 .exp(1−
)
NkbT
Mgh
Π = Π 0 .exp(1−
)
NkbT
Jean Perrin « Les atomes », 1908
Measuring macroscopic a-toms ( 330 nm)
Jean Perrin « Les atomes », 1908
The colloidal atmosphere
Jean Perrin « Les atomes », 1908
Equation of state of van der Waals gas
Jean Perrin « Les atomes », 1908
Extension to charged colloids :Latex particles
0.4 µm
% − V (r )
(
Π = ρ .kT(1 + ρ 2 ∫ ' e k T − 1* .4πr 2 .dr )
'
*)
0 &
∞
V. Reus et al. /Colloidal
Colloids and crystals
Surfaces A: :Physicochem.
latex Eng. Aspects 151 (1999) 449–460
tion
the osmotic
of the
A incrystals
centimetersinduced
of water asby
a function
of the salin
V. ofReus
et al.:pressure
Fusion
of sample
colloidal
monovalent
an
onstant volume fraction equal to 5.5%. Open squares represent samples with a liquid order and
asymmetric
salt:
osmotic
and USAXS
(1999) with the Pois
lline
order. The full
line an
corresponds
to pressure
theoretical osmotic
pressures calculated
Colloidal crystals : latex
V. Reus et al.: Fusion of colloidal crystals induced by monovalent an
Hydroxymethylcellulose-based gels
Cécile Bonnet_Gonnet et al. « Measurement of Forces between Hydroxy propyl cellulose Polymers: Temperature Favored Assembly and Salt Exclusion » (2001)
Synthetic clays : Onsager mechanism
M. Page et al: Osmotic pressure and phase boundary determination
of multiphase systems by analytical ultracentrifugation (2008)
Micelles are colloids
% − V (r )
(
Π = ρ .kT(1 + ρ 2 ∫ ' e k T − 1* .4πr 2 .dr )
'
*)
0 &
∞
The structure of micelles and microemulsions », Y. Chevalier et al. 1991
Long Range Interactions In Nanoscale Science ;
R G French , V A Parsegian et al. (2010)
The devil is the contact pressure !
!
109 Pascals and 0.03 nm3 > 0.2 nm > 0.15 nm2 means DG = 8kT=20 kJ (DH-TDS)
Primary vs secondary hydration force
!
Predicts osmotic pressure and phase limits
!
Primary vs secondary hydration force
F. Oosawa analytical simple expression (1954-1957)
From equation of state to master equation
Van’t Hoff =
Van der Waals fluid / Jean Perrin
-curvature, shape ???
Molecular, colloidal(meso), mechanical
" ∂G %
" ∂G %
" ∂G %
δU mech
=
Π
=
+
+
$
'
$
'
$
'
# ∂V &µ j
# h.∂A &µ j # A.δ h &µ j
∂V