dynamical heterogeneity at the jamming transition of concentrated colloids p. ballesta 1, a. duri 1,...
TRANSCRIPT
Dynamical heterogeneity at the jamming transition of concentrated
colloids
P. Ballesta1, A. Duri1, Luca Cipelletti1,2
1LCVN UMR 5587 Université Montpellier 2 and CNRS, France
2Institut Universitaire de France
Dynamical susceptibility in glassy systems
Supercooled liquid (Lennard-Jones)
Lacevic et al., PRE 2002
4 var[Q(t)]
Outline
• Measuring average dynamics and 4 in colloidal suspensions
• 4 at very high : surprising results!
• A simple model of heterogeneous dynamics
Experimental system & setup
PVC xenospheres in DOPradius ~ 10 m, polydisperse = 64% – 75%Excluded volume interactions
Experimental system & setup
CCD-based (multispeckle)Diffusing Wave Spectroscopy
CCDCamera
Las
er b
eam
Change in speckle field mirrors change in sample configuration
Probe << Rparticle
Time Resolved Correlation
time twlag
degree of correlation cI(tw,) = - 1< Ip(tw) Ip(tw +)>p
< Ip(tw)>p<Ip(tw +)>p
2-time intensity correlation function g2(tw,1
fixed tw, vs.
2-time intensity correlation function
• Initial regime: « simple aging » (s ~ tw1.1 0.1)
• Crossover to stationary dynamics, large fluctuations of s
101 102 103 104 105
0,00
0,02
0,04
0,06
C:\lucacip\doc\papers\WorkInProgress\2004JapanMeeting2003\Figures\Pierre40pcr030422
tw (sec)
1194 4400 7900 14900 21900 44083 54800
n42 n500 n1000 n2000 n3000 n6169 n7700
g 2(t
w,t w
)
-1
(sec)
0 40000 800000
500
1000
C:\lucacip\doc\papers\WorkInProgress\2004JapanMeeting2003\Figures\Pierre40pcr030422
s (se
c)
tw (sec)
TODO: check tw = 0
= 66.4%
Fit: g2(tw,exp[-(/s
(tw))p(tw)]
2-time intensity correlation function
101 102 103 104 105
0,00
0,02
0,04
0,06
C:\lucacip\doc\papers\WorkInProgress\2004JapanMeeting2003\Figures\Pierre40pcr030422
tw (sec)
1194 4400 7900 14900 21900 44083 54800
n42 n500 n1000 n2000 n3000 n6169 n7700
g 2(t
w,t w
)
-1
(sec)
0 40000 800000
500
1000
C:\lucacip\doc\papers\WorkInProgress\2004JapanMeeting2003\Figures\Pierre40pcr030422
s (se
c)
tw (sec)
TODO: check tw = 0
= 66.4%
Fit: g2(tw,exp[-(/s(tw))p(tw)]
Average dynamics :
< s >tw , < p >tw
fixed , vs. tw
fluctuations of the dynamics
var(cI)()
Fluctuations from TRC data
time twlag
degree of correlation cI(tw,) = - 1< Ip(tw) Ip(tw +)>p
< Ip(tw)>p<Ip(tw +)>p
Fluctuations in the DWP model
r
Random number of rearrangements
g2(t,) – 1 fluctuates
r increases
fluctuations increase
Fluctuations
r
Near jamming : small 2 many events small flucutations
Moderate : large 2 few events large flucutations
Fluctuations
10-2 10-1 1 10 102
10-3
10-2
10-1
0.01
0.1
10
var(
c I)
(arb. un.)
1
increasing
decreasing 2
Conclusions
Dynamics heterogeneous
Non-monotonic behavior of *
Competition betweenincreasing size of dynamically correlated regions ...
Conclusions
Dynamics heterogeneous
Non-monotonic behavior of *
Competition betweenincreasing size of dynamically correlated regions anddecreasing effectiveness ofrearrangements
Conclusions
Dynamics heterogeneous
Non-monotonic behavior of *
Competition betweenincreasing size of dynamically correlated regions anddecreasing effectiveness ofrearrangements
Dynamical heterogeneity dictated by the number of rearrangements needed to decorrelate
Average dynamics vs
0.64 0.68 0.72 0.76
103
104
c= 0.752
s (se
c)
eff
s ~ |
eff
c|-1.01
Average relaxation time
Dynamical hetereogeneity in glassy systems
Supercooled liquid (Lennard-Jones)
Glotzer et al., J. Chem. Phys. 2000
4 increases when approaching Tg
Conclusions
Dynamics heterogeneous
Non-monotonic behavior of *
Many localized, highly effective rearrangements
Conclusions
Dynamics heterogeneous
Non-monotonic behavior of *
Many localized, highly effective rearrangements
Many extended, poorly effective rearrangements
Conclusions
Dynamics heterogeneous
Non-monotonic behavior of *
Many localized, highly effective rearrangements
Many extended, poorly effective rearrangements
Few extended, quite effectiverearrangements
General behavior
Time Resolved Correlation
time twlag
degree of correlation cI(tw,) = - 1< Ip(tw) Ip(tw +)>p
< Ip(tw)>p<Ip(tw +)>p