Fluorescence Spectroscopy as a Tool for Investigating the Self-Organized Polyelectrolyte Systems - Self Organized Nanostructures of Amphiphilic Block Copolymers - page 228

There were two reasons for using the mean correlation time, τ mean , rather than

relaxation times of individual modes, τ i : (a) experimental data were analyzed in the

same way, (b) individual components, τ i , reflect different types of the real motion,

but they have no clear physical meaning in the coarse-grained model.

4.1.2 Conformational Behavior

Here, we summarize the patterns of conformational behavior that obviously affect
the fluorescence anisotropy decay. For a detailed discussion we refer the reader
to the original paper and references therein [ 87 ] . The conformational behavior of
the polymer reproduced by simulations is in line with theoretical predictions [ 99 ]
as well as other simulation works [ 104 , 105 ] . The basic trends are depicted by a
few snapshots in Fig. 20 . With increasing degree of charging, the polymer under-
goes the following conformations: a collapsed spherical conformation (Fig. 20 a )
deforms first in a prolate ellipsoid (Fig. 20 b ). At higher degrees of charging, it goes
through a series of pearl-necklace structures with gradually increasing number of
pearls (Fig. 20 c ). At high degrees of ionization, it ends up in an expanded confor-
mation (Fig. 20 d ).

4.1.3 Comparison of Simulated and Experimental Data

The simulation study was aimed at the question of whether our intuitive interpre-
tation of experimental fluorescence anisotropy data on PMA solutions was correct

Fig. 20 Polyelectrolyte conformation as a function of the degree of dissociation ( α ) . Simulation

snapshots of the polymer with ε = 1.3, for several degrees of ionization: α = 0.06 ( a ), α = 0.20

( b ), 0.33 ( d ). Counterions not shown. For better visibility the snapshots

differ in magnification; the real sizes of the monomer units are the same in all cases

α = 0.25 ( c ), and α =