Interpolyelectrolyte Complexes Based on Polyionic Species of Branched Topology - Self Organized Nanostructures of Amphiphilic Block Copolymers - page 146

0.20

homogeneous
system

0.16

Z < Z M

0.12

0.08

Z > Z M

0.04

heterogeneous
system

0.00

0.0 0.2 0.4 0.6 0.8 1.0

Z M

Z = [+] / [-]

Fig. 12 Turbidimetric titration curve of the aqueous solution of PIB- b -PMANa micelles with the
aqueous solution of P4VPQ. Z is the ratio of the concentrations of the ionic groups,

COO − ]
of the polymeric components. Phase separation occurred above the threshold value Z M . Reprinted
from [ 66 ] with permission from the American Chemical Society

N + ] / [

[

PMANa micelles and P4VPQ remained transparent, thus strongly suggesting the
formation of water-soluble IPECs enriched by ionic groups of the micelle-forming
polymeric component. This trend is very similar to that discussed in Sect. 2.1 for
the formation of IPECs between star-shaped HPE and linear GPE chains.
The examination of homogeneous mixtures of the PIB- b -PMANa micelles and
P4VPQ at Z Z M carried out using various techniques, including AUC [ 66 , 67 ] ,

fluorescence spectroscopy (with the use of pyrene as a polarity probe) [ 66 , 67 ] ,
DLS [ 67 - 69 ], small-angle neutron scattering (SANS) [ 67 - 69 ], and cryogenic trans-
mission electron microscopy (cryo-TEM) [ 69 ] , provided evidence that the formed
water-soluble IPECs have peculiar onion-like (or multilayer) micellar structure. It is
remarkable that the hydrodynamic sizes [ 67 - 69 ] and morphologies [ 69 ] ofsuch
macromolecular co-assemblies were found to be quite close to or virtually the same
as those of the original PIB- b -PMANa micelles. These observations suggest that,
similarly to IPECs based on star-shaped HPEs, the co-assembly between micelles
with PE coronas and chains of oppositely charged linear GPE results in intra-coronal
disproportionation of PE blocks. A certain fraction of such blocks is completely em-
bedded in the complex coacervate shell, whereas the rest of the coronal blocks only
contribute a small number of their monomer units in the shell domain and form the
lyophilizing corona.
According to the authors of [ 66 - 69 ] , each of the water-soluble complex species
contains a hydrophobic core formed by PIB blocks (A in Fig. 13 ) , which is sur-
rounded by a compact complex coacervate inner shell assembled from oppositely
charged fragments of the polymeric components (PMA − blocks and P4VPQ +
chains) (B in Fig. 13 ) and by a hydrophilic (ionic) corona built up from excess

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