Glass and jamming transitions in soft particles made of PNIPAM and Poly(acrylic acid)

The aim of the present proposal is to investigate dynamics and structure of soft microgel particles composed of Interpenetrating Polymer Networks (IPN) of poly(N-isopropylacrylamide) (PNIPAM) and poly(acrylic acid) (PAAc) dispersed in water through XPCS and SAXS. The study will be performed on an IPN microgel at high PAAc content that, in a recent rheological study [1], has revealed liquid-glass and glass-jammed transitions at increasing concentration. Moreover, the system is characterized by a volume phase transition (VPT) from a swollen to a shrunken state around T=305 K, therefore it would be interesting to probe the dynamics and structure as a function of temperature across the VPT for a microgel with high PAAc content, at high concentration. In these conditions, the VPT will be accompanied by a transition from a liquid to an arrested state and to a change in the particle softness [2].