Interplay between the glass and the gel transition

By changing the control parameters, many physical systems reach a slow dynamics regime followed by an arrested or a quasi-arrested state. Examples, among others, are gels and glasses. In this paper, we discuss some experimental and theoretical results in polymer and colloidal systems, where gel and glass transitions interfere, and use models from Mode Coupling Theory (MCT) to illustrate the rich phenomenology observed. The continuous and the discontinuous transition lines, found in the MCT models, are considered suitable to describe respectively the gel and the glass transitions, so we suggest that the interplay between gel and glass may be interpreted in terms of the F-13 MCT model, clarifying also the origin of logarithmic decays often observed in such systems. In particular, the theoretical predictions of the MCT in the F-13 model are compared with Molecular Dynamics simulations in model systems for chemical gels and charged colloids.