  The chemical fueling of transient states (CFTS) is a powerful process to
control the nonequilibrium structuring and the homeostatic function of adaptive
soft matter systems. Here, we introduce a mean-field model of CFTS based on the
activation of metastable equilibrium states in a tilted Landau bistable energy
landscape along a coarse-grained reaction coordinate (or order parameter)
triggered by a nonmonotonic two-step chemical fueling reaction. Evaluation of
the model in the quasi-static (QS) limit - valid for fast system relaxation -
allows us to extract useful analytical laws for the critical activation
concentration and duration of the transient states in dependence of physical
parameters, such as rate constants, fuel concentrations, and the system's
distance to its equilibrium transition point. We apply our model in the QS
limit to recent experiments of CFTS of collapsing responsive microgels and find
a very good performance with only a few global and physically interpretable
fitting parameters, which can be employed for programmable material design.
Moreover, our model framework also allows a thermodynamic analysis of the
energy and performed work in the system. Finally, we go beyond the QS limit,
where the system's response is slow and retarded versus the chemical reaction,
using an overdamped Smoluchowski approach. The latter demonstrates how internal
system time scales can be used to tune the time-dependent behavior and
programmed delay of the transient states in full nonequilibrium.
