Article Dans Une Revue Journal of Applied Crystallography Année : 2025

Phase behavior of silica-PNIPAm nanogels under high hydrostatic pressure

Résumé

The structure and dynamics of concentrated silica-PNIPAm (poly- N -isopropylacrylamide) nanogels are studied as a function of hydrostatic pressure up to 3500 bar. A combination of X-ray photon correlation spectroscopy and small-angle X-ray scattering shows similar characteristics of the dynamics for both temperature- and pressure-induced volume phase transitions of PNIPAm nanogels. Upon increasing the pressure and depending on the initial particle volume fraction, a transition from a liquid or glass state to a colloidal gel is observed for pressures p ≃ 1500 bar at a temperature of 293 K. Time-dependent analysis of the dynamics shows aging in glass and gel samples which is absent in the liquid state. This indicates stress-dominated dynamics upon pressure changes that equilibrate after a few hundred seconds.

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hal-05122232 , version 1 (20-06-2025)

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Nele N Striker, Christina Krywka, Claudia Goy, Svenja C Hövelmann, Niels C Giesselmann, et al.. Phase behavior of silica-PNIPAm nanogels under high hydrostatic pressure. Journal of Applied Crystallography, 2025, 58 (3), pp.919-926. ⟨10.1107/S1600576725003188⟩. ⟨hal-05122232⟩
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