posted on 2021-03-23, 14:50authored byMingge Zhao, Xiang Li, Junhan Cho
To
understand the responses of self-assembly in mixtures containing
zwitterionic amphiphilic chains to high pressure, we introduce a self-consistent
field theory in combination with a molecular equation-of-state model
for them in a primitive way. The free energy density for those in
the bulk state is first formulated. Its locally equilibrated excess
part is then incorporated into Edwards Hamiltonian along with the
electrostatic energy contributions to elicit the saddle point approximation
to the partition function with proper self-consistent field equations.
It is shown that charge–charge correlations enhance self-assembling
tendency for the amphiphiles with the opposite charges on one component
side, as the medium dielectric constant εr decreases.
Those with the opposite charges at the two chain ends respond in a
more complicated way to εr. Densification by applied
pressure strengthens the self-assembly for both at a moderate εr, similar to typical phospholipids, but pressure effects are
strongly dependent on the position of charges along the chains at
a lower εr. It is argued that the manipulation of
the dielectric environment and disparity in component dispersion interactions
can yield useful materials exhibiting various types of baroresponsivity
or thermoresponsivity with re-entrant self-assembly.