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For a mesoscopic colloidal particle embedded in a critical medium a distant perturbation induces
changes of the pressure onto the colloid surface and of the density in the scaling region near the
surface that are related in a universal way. This applies to critical media such as a critical binary
liquid mixture [1] or a dilute solution of long flexible nonadsorbing polymers [2] and to perturbations
such as another colloidal particle or a planar wall. While the case of colloidal particles with radius
R much larger than the surface-to-surface distance D can - via the Deriagin approximation - be
reduced to the problem of two parallel walls, the present talk will mainly concentrate on the lesser
investigated case where the mesoscopic radius R is much smaller than D and the correlation length
ξ (the so-called "nanoparticle case" or "protein limit"). Here the perturbed density profiles (of
the order parameter or the polymer material) can be explored by means of a new type of field
theoretical "fusion expansion" [3]. Applications to both spherical [3,4] and non-spherical [4,5]
nanoparticles will be presented.
[1] T.W. Burkhardt and T. Xue, Phys. Rev. Lett. 66, 895 (1991); E. E. and M. Stapper, Phys. Rev. B50, 10009 (1994). [2] E. E., Phys. Rev. E55, 3116 (1997); H.-P. Hsu and P. Grassberger, Eur. Phys. J. B36, 209 (2003); J. Chem. Phys. 120, 2034 (2004); E. E., in Soft Matter, edited by G. Gompper and M. Schick (Wiley-VCH 2006), Vol. 2. [3] E. E., J. Chem. Phys. 130, 134902 (2009). [4] A. Hanke et al, Phys. Rev. E59, 6853 (1999); E. E., J. Phys. Cond. Mat. 12, A227 (2000); T. Odijk, J. Phys. Chem. B113, 3941 (2009). [5] E. E. and A. Bringer, J. Chem. Phys. 127, 034904 (2007). 1 |
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