Microgel suspensions of an interpenetrated Polymer Network (IPN) of PNIPAM and PAAc in D2O have been investigated through dynamic light scattering as a function of temperature, pH and concentration across the Volume Phase Transition (VPT). The dynamics of the system is slowed down under H/D isotopic substitution due to different balance states between polymer/polymer and polymer/solvent interactions suggesting the crucial role played by H-bonding. The swelling behavior, reduced with respect to PNIPAM and water, has been described by the Flory–Rehner theory, tested for PNIPAM microgel and successfully expanded to higher order for IPN microgels. Moreover the concentration dependence of the relaxation time at neutral pH has highlighted two different routes to approach the glass transition: Arrhenius and super-Arrhenius (Vogel Fulcher Tammann) respectively below and above the VPT and a fragility plot has been derived. Fragility can be tuned by changing temperature: across the VPT particles undergo a transition from soft-strong to stiff-fragile.

Dynamical behavior of microgels of interpenetrated polymer networks / Nigro, Valentina; Angelini, Roberta; Bertoldo, Monica; Bruni, Fabio; Ricci, Maria Antonietta; Ruzicka, Barbara. - In: SOFT MATTER. - ISSN 1744-683X. - STAMPA. - 13:30(2017), pp. 5185-5193. [10.1039/c7sm00739f]

Dynamical behavior of microgels of interpenetrated polymer networks

NIGRO, VALENTINA;ANGELINI, ROBERTA;RICCI, Maria Antonietta;RUZICKA, BARBARA
2017

Abstract

Microgel suspensions of an interpenetrated Polymer Network (IPN) of PNIPAM and PAAc in D2O have been investigated through dynamic light scattering as a function of temperature, pH and concentration across the Volume Phase Transition (VPT). The dynamics of the system is slowed down under H/D isotopic substitution due to different balance states between polymer/polymer and polymer/solvent interactions suggesting the crucial role played by H-bonding. The swelling behavior, reduced with respect to PNIPAM and water, has been described by the Flory–Rehner theory, tested for PNIPAM microgel and successfully expanded to higher order for IPN microgels. Moreover the concentration dependence of the relaxation time at neutral pH has highlighted two different routes to approach the glass transition: Arrhenius and super-Arrhenius (Vogel Fulcher Tammann) respectively below and above the VPT and a fragility plot has been derived. Fragility can be tuned by changing temperature: across the VPT particles undergo a transition from soft-strong to stiff-fragile.
2017
Chemistry (all); Condensed Matter Physics; Soft Matter; Colloids; Microgels
01 Pubblicazione su rivista::01a Articolo in rivista
Dynamical behavior of microgels of interpenetrated polymer networks / Nigro, Valentina; Angelini, Roberta; Bertoldo, Monica; Bruni, Fabio; Ricci, Maria Antonietta; Ruzicka, Barbara. - In: SOFT MATTER. - ISSN 1744-683X. - STAMPA. - 13:30(2017), pp. 5185-5193. [10.1039/c7sm00739f]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1005838
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