Fig. 1. Enthalpy-driven and entropy-driven crosslinking in physical networks.

Schematic illustrating a network formed by physical interactions that can be individually symbolized as complementary binding interactions with corresponding thermodynamic constants. Two categories of binding interactions can be described—enthalpy-driven and entropy-driven interactions—which exhibit different responses to changes in temperature. The storage modulus (G′) of a physical network is represented by a plateau modulus (G₀(T)) and a frequency-dependent single-mode Maxwell term (g(ω,T)). For simple physical networks, the relaxation constant is equivalent to the dissociation rate constant (k_d) of the complementary crosslinking interactions⁵⁵. Enthalpy-driven crosslinks exhibit faster dissociation rates and network softening at elevated temperatures, while entropy-driven crosslinks dampen these temperature-induced changes in network relaxation, yielding either temperature-independent viscoelasticity or network stiffening.