The structure of the self-assemblies
formed by amphiphilic comblike
copolyelectrolytes dispersed in water has been investigated by scattering
techniques (light and neutron) and by transmission electronic microscopy.
The comblike polymers consisted of a polystyrene backbone grafted
with a fixed amount of pendant <i>N</i>,<i>N</i>-dimethyl quaternary ammonium alkyl groups of various lengths ranging
from C12 up to C18. In aqueous solution, the polymers self-assembled
into small spherical aggregates at low concentrations and into cylindrical
aggregates above a critical concentration with a diameter that increased
with the length of the alkyl side chains. The length of the cylindrical
aggregates increased with increasing concentration, and branching
occurred at higher concentration, which induced gelation above a critical
percolation concentration. Growth and branching were favored by increasing
the ionic strength of the solution. The dynamics slowed down with
decreasing temperature and increasing alkyl length, and the assemblies
of polymers with C16 and C18 pendant chains were kinetically frozen
at 20 °C
