We apply molecular dynamics simulations to investigate the structure formation of amphiphilic Janus particles in the bulk phase. The Janus particles are modeled as (soft) spheres composed of a hydrophilic and hydrophobic part. Their orientation is described by a vector representing an internal degree of freedom. Investigating energy fluctuations and cluster size distributions, we determine the aggregation line in a temperature-density-diagram, where the reduced temperature is an inverse measure for the anisotropic coupling. Below this aggregation line clusters of various sizes depending on density and reduced temperature are found. For low densities in the range ρ* ⩽ 0.3, the cluster size distribution has a broad maximum, indicating simultaneous existence of various cluster sizes between 5 and 10. We find no hint of a condensation transition of these clustered systems. In the case of higher densities (ρ* = 0.5 and 0.6), the cluster size distribution shows an extremely narrow peak at clusters of size 13. In these icosahedrons, the particles are arranged in a closed-packed manner, thereby maximizing the number of bonds. Analyzing the translational mean-square displacement we also observe indications of hindered diffusion due to aggregation.

1.
C.
Casagrande
,
P.
Fabre
,
E.
Raphaël
, and
M.
Veyssié
,
Europhys. Lett.
9
,
251
(
1989
).
2.
A.
Perro
,
S.
Reculusa
,
S.
Ravaine
,
E.
Bourgeat-Lami
, and
E.
Duguet
,
J. Mater. Chem.
15
,
3745
(
2005
).
3.
S.
Gangwal
,
O. J.
Cayre1
,
M. Z.
Bazant
, and
O. D.
Velev
,
Phys. Rev. Lett.
100
,
058302
(
2008
).
4.
S.
Gangwal
,
A.
Pawar
,
K.
Ilona
, and
O. D.
Velev
,
Soft Matter
6
,
1413
(
2010
).
5.
S.
Mornet
,
S.
Vasseur
,
F.
Grasset
, and
E.
Duguet
,
J. Mater. Chem.
14
,
2161
(
2004
).
6.
L.
Hong
,
A.
Cacciuto
,
E.
Luijten
, and
S.
Granick
,
Langmuir
24
,
621
(
2008
).
7.
A. B.
Pawar
and
I.
Kretzschmar
,
Macromol. Rapid Commun.
31
,
150
(
2010
).
8.
D.
Suzuki
and
H.
Kawaguchi
,
Colloid Polym. Sci.
284
,
1471
(
2006
).
9.
S.-H.
Kim
,
S.-J.
Jeon
,
W. C.
Jeong
,
H. S.
Park
, and
S.-M.
Yang
,
Adv. Mater.
20
,
4129
(
2008
).
10.
J. N.
Anker
and
R.
Kopelman
,
Appl. Phys. Lett.
82
,
1102
(
2003
).
11.
C. J.
Behrend
,
J. N.
Anker
,
B. H.
McNaughton
,
M.
Brasuel
,
M. A.
Philbert
, and
R.
Kopelman
,
J. Phys. Chem. B
108
,
10408
(
2004
).
12.
J.-W.
Kim
,
D.
Lee
,
H. C.
Shum
, and
D. A.
Weitz
,
Adv. Mater.
20
,
3239
(
2008
).
13.
N.
Glaser
,
D. J.
Adams
,
A.
Böker
, and
G.
Krausch
,
Langmuir
22
,
5227
(
2006
).
14.
S.
Jiang
,
Q.
Chen
,
M.
Tripathy
,
E.
Luijten
,
K. S.
Schweizer
, and
S.
Granick
,
Adv. Mater.
22
,
1060
(
2010
).
15.
F.
Sciortino
,
A.
Giacometti
, and
G.
Pastore
,
Phys. Rev. Lett.
103
,
237801
(
2009
).
16.
F.
Sciortino
,
A.
Giacometti
, and
G.
Pastore
,
Phys. Chem. Chem. Phys.
12
,
11869
(
2010
).
17.
A. M.
Somoza
,
E.
Chacón
,
L.
Mederos
, and
P.
Tarazona
,
J. Phys.: Condens. Matter
7
,
5753
(
1995
).
18.
J. R.
Millman
,
K. H.
Bhatt
,
B. G.
Prevo
, and
O. D.
Velev
,
Nature Mater.
4
,
98
(
2005
).
19.
T.
Erdmann
,
M.
Kröger
, and
S.
Hess
,
Phys. Rev. E
67
,
041209
(
2003
).
20.
C.
Guerra
,
A. M.
Somoza
, and
M. M.
Telo da Gama
,
J. Chem. Phys.
109
,
1152
(
1998
).
21.
N.
Kern
and
D.
Frenkel
,
J. Chem. Phys.
118
,
9882
(
2003
).
22.
A.
Giacometti
,
F.
Lado
,
J.
Largo
,
G.
Pastore
, and
F.
Sciortino
,
J. Chem. Phys.
131
,
174114
(
2009
).
23.
G.
Rosenthal
and
S. H. L.
Klapp
,
J. Chem. Phys.
134
,
154707
(
2011
).
24.
D. C.
Rapaport
,
The Art of Molecular Dynamics Simulation
, 2nd ed. (
Cambridge University Press
,
2004
).
25.
H. J. C.
Berendsen
,
J. P. M.
Postma
,
W. F.
van Gunsteren
,
A.
DiNola
, and
J. R.
Haak
,
J. Chem. Phys.
81
,
3684
(
1984
).
26.
T.
Morishita
,
J. Chem. Phys.
113
,
2976
(
2000
).
27.
H.
Schmidle
,
C. K.
Hall
,
O. D.
Velev
, and
S. H. L.
Klapp
,
Soft Matter
8
,
1521
(
2012
).
28.
M.
Sammalkorpi
,
S.
Sanders
,
A. Z.
Panagiotopoulos
,
M.
Karttunen
, and
M.
Haataja
,
J. Phys. Chem. B
115
,
1403
(
2011
).
29.
D. S.
Rokhsar
,
N. D.
Mermin
, and
D. C.
Wright
,
Phys. Rev. B.
35
,
5487
(
1987
).
30.
A. L.
Mackay
,
Acta Crystallogr.
15
,
916
(
1962
).
31.
J. D.
Honeycutt
and
H. C.
Andemen
,
J. Phys. Chem.
91
,
4950
(
1987
).
32.
J.
Farges
,
M. F.
De Feraudy
,
B.
Raoult
, and
G.
Torchet
,
Surf. Sci.
156
,
370
(
1985
).
33.
C. G.
Gray
and
K. E.
Gubbins
,
Theory of Molecular Fluids
(
Clarendon
,
Oxford
,
1984
).
34.
E.
Del Gado
and
W.
Kob
,
Soft Matter
6
,
1547
(
2010
).
35.
R. D.
Mountain
and
D.
Thirumalai
,
J. Chem. Phys.
92
,
6116
(
1990
).
36.
F. W.
Starr
,
J. K.
Nielsen
, and
H. E.
Stanley
,
Phys. Rev. E
62
,
579
(
2000
).
37.
L.
Rovigatti
,
J.
Russo
, and
F.
Sciortino
,
Phys. Rev. Lett.
107
,
237801
(
2011
).
38.
D.
Holland-Moritz
,
D. M.
Herlach
, and
K.
Urban
,
Phys. Rev. Lett.
71
,
1196
(
1993
).
39.
D.
Arthur
and
S.
Vassilvitskii
, “
k-means++: The advantages of careful seeding
,” in
Proceedings of the Eighteenth Annual ACM-SIAM Symposium, SODA 2007, New Orleans, Louisiana, USA
(
Society of Industrial and Applied Mathematics (SIAM)
,
Philadelphia, PA
,
2007
).
40.
D. L.
Davies
and
D. W.
Bouldin
,
IEEE Trans. Pattern. Anal. Mach. Intell.
PAMI-1
,
224
(
1979
).
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