Local structure of temperature and pH-sensitive colloidal microgels

Journal Article · Mon Sep 21 00:00:00 EDT 2015 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4930885· OSTI ID:22489626

Nigro, Valentina; Bruni, Fabio; Ricci, Maria Antonietta ^[1]; Angelini, Roberta; Ruzicka, Barbara ^[2]; Bertoldo, Monica ^[3]; Castelvetro, Valter ^[4]; Rogers, Sarah ^[5]

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1. Dipartimento di Scienze, Sezione di Nanoscienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy)
2. Istituto dei Sistemi Complessi del Consiglio Nazionale delle Ricerche (ISC-CNR) UOS Sapienza and Dipartimento di Fisica, Sapienza Università, Pz.le Aldo Moro 5, I-00185 Roma (Italy)
3. Istituto per i Processi Chimico-Fisici del Consiglio Nazionale delle Ricerche (IPCF-CNR), Area della Ricerca, Via G. Moruzzi 1, I-56124 Pisa (Italy)
4. Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via G. Moruzzi 3, I-56126 Pisa (Italy)
5. ISIS-STFC, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX (United Kingdom)

The temperature dependence of the local intra-particle structure of colloidal microgel particles, composed of interpenetrated polymer networks, has been investigated by small-angle neutron scattering at different pH and concentrations, in the range (299÷315) K, where a volume phase transition from a swollen to a shrunken state takes place. Data are well described by a theoretical model that takes into account the presence of both interpenetrated polymer networks and cross-linkers. Two different behaviors are found across the volume phase transition. At neutral pH and T ≈ 307 K, a sharp change of the local structure from a water rich open inhomogeneous interpenetrated polymer network to a homogeneous porous solid-like structure after expelling water is observed. Differently, at acidic pH, the local structure changes almost continuously. These findings demonstrate that a fine control of the pH of the system allows to tune the sharpness of the volume-phase transition.

• OSTI ID: 22489626
• Journal Information: Journal of Chemical Physics, Vol. 143, Issue 11; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CONCENTRATION RATIO
CONTROL
NEUTRON DIFFRACTION
PARTICLE STRUCTURE
PARTICLES
PH VALUE
PHASE TRANSFORMATIONS
POLYMERS
POROUS MATERIALS
SMALL ANGLE SCATTERING
SOLIDS
TEMPERATURE DEPENDENCE
WATER