
340 Meshless methods and their numerical properties
the negative mobile ion
Cl
−
has a lower value of concentration inside
the hydrogel when compared with the solution, as shown in Figure7.27d
and e, due to the repulsive force between the anionic xed charge and the
mobile ion
.
Also, as the anionic xed charge groups are bound to the hydrogel cross-
linked network of polymers, the hydrogel has a higher negative chemical
potential than the surrounding solutions, which further reduces the diffusion
of mobile ions
into the hydrogel. Figure7.28 shows the distribution of
cumulative concentrations of all the mobile ions
123
in the ...