How do Self-Assembling Polymers and Gels Age Compared to Glasses?

Experiments on gels have provided contradictory results concerning the relation between correlation and response functions during aging. To clarify this puzzle, we numerically investigate the fluctuation-dissipation plot in equilibrium polymers and in network forming gels employing two distinct observables, (i) the density Fourier transform and (ii) the single-particle potential energy, to probe (i) diffusional processes and (ii) the development of a bond network. The plot behaves very differently for the two cases. Violation from the equilibrium behavior is found only for the second observable. The experimental implications of the discovered sensitivity to the choice of the probe are discussed, in particular, with respect to the existing experimental results.