Effect of organic and inorganic ions on the lower critical solution transition and aggregation of PNIPAM
| Autor: | Jordi Faraudo, Delfi Bastos-González, Carlos Drummond, Leonor Pérez-Fuentes |
|---|---|
| Přispěvatelé: | Biocolloid and Fluid Physics Group, University of Granada [Granada], Institut de Ciència de Materials de Barcelona (ICMAB), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Centre de Recherche Paul Pascal (CRPP), Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS) |
| Rok vydání: | 2018 |
| Předmět: |
Kosmotropic
Hofmeister series Chemistry Ionic bonding [CHIM.MATE]Chemical Sciences/Material chemistry 02 engineering and technology General Chemistry Inorganic ions 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Lower critical solution temperature 0104 chemical sciences Dynamic light scattering Chemical engineering 13. Climate action Phase (matter) Molecule [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] 0210 nano-technology |
| Zdroj: | Soft Matter Soft Matter, Royal Society of Chemistry, 2018, 14 (38), pp.7818-7828. ⟨10.1039/c8sm01679h⟩ |
| ISSN: | 1744-6848 1744-683X |
| DOI: | 10.1039/c8sm01679h |
| Popis: | International audience; We have studied the effect of different ions belonging to the extended Hofmeister series on the thermosensitive polymer poly(N-isopropylacrylamide) (PNIPAM), by combining Differential Scanning Calorimetry (DSC) and Dynamic Light Scattering (DLS). The variations in the lower critical solution temperature (TLCS) and enthalpy change during PNIPAM phase separation evidence the importance of considering both hydration and hydrophobicity to explain the interaction of ions with interfaces. The results obtained in the presence of inorganic ions can be explained by the tendency of water molecules to preferentially hydrate the PNIPAM chains or the ions, depending on the kosmotropic (highly hydrated) or chaotropic (poorly hydrated) character of the ions. On the contrary, tetraphenyl organic ions (Ph4B− and Ph4As+) interact with the hydrophobic moieties of PNIPAM chains, inducing a significant reduction of the TLCS. DLS results show that the aggregation state of PNIPAM above the TLCS is also strongly influenced by the presence of ions. While macroscopic phase separation (formation of a polymer-rich phase insoluble in water) was apparent in the presence of inorganic ions, we observed the formation of submicron PNIPAM aggregates at temperatures above the TLCS in the presence of the hydrophobic ions. Kinetically arrested monodisperse PNIPAM nanoparticles were formed in the presence of the Ph4B− anion, while a rather polydisperse distribution of particle sizes was observed in the presence of Ph4As+. These results show that ionic specificity influences both the static (thermodynamic) and dynamic (kinetically controlled aggregation) states of PNIPAM in an aqueous environment. |
| Databáze: | OpenAIRE |
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