Interpenetrated Polymer Network (IPN) microgels of PNIPAM and PAAc have been investigated and the experimental data have been compared with theoretical models from the Flory–Rehner theory. We confirm that the swelling behavior of PNIPAM microgels is well described by this theory by considering the second order approximation for the volume fraction ϕ dependence of the Flory parameter χ(ϕ). Indeed the Volume-Phase Transition (VPT) of the PNIPAM-PAAc IPN microgel at neutral conditions and in D⁠2O solvents can be well described only considering a third-order approximation. Interestingly we empirically find that sharper is the transition higher is the order of the χ(ϕ) relation which has to be considered. Moreover the VPT can be experimentally controlled by tuning the polymer/solvent interactions through pH and solvent allowing to directly modify the delicate balance between energetic and entropic contributions and to explore the swelling behavior in a wide range of environmental conditions. In particular we find that the most advantageous condition for swelling is in water at acidic pH.

Swelling of responsive-microgels: experiments versus models / Nigro, Valentina; Angelini, Roberta; Bertoldo, Monica; Ruzicka, Barbara. - In: COLLOIDS AND SURFACES. A, PHYSICOCHEMICAL AND ENGINEERING ASPECTS. - ISSN 0927-7757. - STAMPA. - 532:(2017), pp. 389-396. [10.1016/j.colsurfa.2017.04.059]

Swelling of responsive-microgels: experiments versus models

NIGRO, VALENTINA
;
ANGELINI, ROBERTA;RUZICKA, BARBARA
2017

Abstract

Interpenetrated Polymer Network (IPN) microgels of PNIPAM and PAAc have been investigated and the experimental data have been compared with theoretical models from the Flory–Rehner theory. We confirm that the swelling behavior of PNIPAM microgels is well described by this theory by considering the second order approximation for the volume fraction ϕ dependence of the Flory parameter χ(ϕ). Indeed the Volume-Phase Transition (VPT) of the PNIPAM-PAAc IPN microgel at neutral conditions and in D⁠2O solvents can be well described only considering a third-order approximation. Interestingly we empirically find that sharper is the transition higher is the order of the χ(ϕ) relation which has to be considered. Moreover the VPT can be experimentally controlled by tuning the polymer/solvent interactions through pH and solvent allowing to directly modify the delicate balance between energetic and entropic contributions and to explore the swelling behavior in a wide range of environmental conditions. In particular we find that the most advantageous condition for swelling is in water at acidic pH.
2017
colloidal suspensions; microgels; swelling behavior; dynamic light scattering
01 Pubblicazione su rivista::01a Articolo in rivista
Swelling of responsive-microgels: experiments versus models / Nigro, Valentina; Angelini, Roberta; Bertoldo, Monica; Ruzicka, Barbara. - In: COLLOIDS AND SURFACES. A, PHYSICOCHEMICAL AND ENGINEERING ASPECTS. - ISSN 0927-7757. - STAMPA. - 532:(2017), pp. 389-396. [10.1016/j.colsurfa.2017.04.059]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/964651
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