Interfacial Behavior of Solid- and Liquid-like Polyelectrolyte Complexes as a Function of Charge Stoichiometry
We systematically investigate in this work the surface activity of polyelectrolyte complex (PECs) suspensions as a function of the molar charge ratio Z (= [-]/[+]) from two model systems: the weakly and strongly interacting poly (diallyldimethylammonium chloride)/poly (acrylic acid sodium salt) (PDA...
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2021
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oai:doaj.org-article:cf312428dabe4a148c3f879f8f5c184e2021-11-11T18:48:59ZInterfacial Behavior of Solid- and Liquid-like Polyelectrolyte Complexes as a Function of Charge Stoichiometry10.3390/polym132138482073-4360https://doaj.org/article/cf312428dabe4a148c3f879f8f5c184e2021-11-01T00:00:00Zhttps://www.mdpi.com/2073-4360/13/21/3848https://doaj.org/toc/2073-4360We systematically investigate in this work the surface activity of polyelectrolyte complex (PECs) suspensions as a function of the molar charge ratio Z (= [-]/[+]) from two model systems: the weakly and strongly interacting poly (diallyldimethylammonium chloride)/poly (acrylic acid sodium salt) (PDADMAC/PANa) and poly (diallyldimethylammonium chloride)/poly (sodium 4- styrenesulfonate) (PDADMAC/PSSNa) pairs, respectively. For both systems, the PEC surface tension decreases as the system approaches charge stoichiometry (Z = 1) whenever the complexation occurs in the presence of excess PDADMAC (Z < 1) or excess polyanion (Z > 1) consistent with an increased level of charge neutralization of PEs forming increasingly hydrophobic and neutral surface-active species. The behavior at stoichiometry (Z = 1) is also particularly informative about the physical nature of the complexes. The PDADMAC/PANa system undergoes a liquid–liquid phase transition through the formation of coacervate microdroplets in equilibrium with macroions remaining in solution. In the PDADMAC/PSSNa system, the surface tension of the supernatant was close to that of pure water, suggesting that the PSSNa-based complexes have completely sedimented, consistent with a complete liquid–solid phase separation of an out-of-equilibrium system. Besides, the high sensitivity of surface tension measurements, which can detect the presence of trace amounts of aggregates and other precursors in the supernatant, allows for very accurate determination of the exact charge stoichiometry of the complexes. Finally, the very low water/water interfacial tension that develops between the dilute phase and the denser coacervate phase in the PDADAMAC/PANa system was measured using the generalized Young–Laplace method to complete the full characterization of both systems. The overall study showed that simple surface tension measurements can be a very sensitive tool to characterize, discriminate, and better understand the formation mechanism of the different structures encountered during the formation of PECs.Hongwei LiMartin FauquignonMarie HaddouChristophe SchatzJean-Paul ChapelMDPI AGarticlepolyelectrolyte complexescomplex coacervatesliquid–liquid and liquid–solid transitionsurface tensionpendant dropinterfacial tensionOrganic chemistryQD241-441ENPolymers, Vol 13, Iss 3848, p 3848 (2021) |
| institution |
DOAJ |
| collection |
DOAJ |
| language |
EN |
| topic |
polyelectrolyte complexes complex coacervates liquid–liquid and liquid–solid transition surface tension pendant drop interfacial tension Organic chemistry QD241-441 |
| spellingShingle |
polyelectrolyte complexes complex coacervates liquid–liquid and liquid–solid transition surface tension pendant drop interfacial tension Organic chemistry QD241-441 Hongwei Li Martin Fauquignon Marie Haddou Christophe Schatz Jean-Paul Chapel Interfacial Behavior of Solid- and Liquid-like Polyelectrolyte Complexes as a Function of Charge Stoichiometry |
| description |
We systematically investigate in this work the surface activity of polyelectrolyte complex (PECs) suspensions as a function of the molar charge ratio Z (= [-]/[+]) from two model systems: the weakly and strongly interacting poly (diallyldimethylammonium chloride)/poly (acrylic acid sodium salt) (PDADMAC/PANa) and poly (diallyldimethylammonium chloride)/poly (sodium 4- styrenesulfonate) (PDADMAC/PSSNa) pairs, respectively. For both systems, the PEC surface tension decreases as the system approaches charge stoichiometry (Z = 1) whenever the complexation occurs in the presence of excess PDADMAC (Z < 1) or excess polyanion (Z > 1) consistent with an increased level of charge neutralization of PEs forming increasingly hydrophobic and neutral surface-active species. The behavior at stoichiometry (Z = 1) is also particularly informative about the physical nature of the complexes. The PDADMAC/PANa system undergoes a liquid–liquid phase transition through the formation of coacervate microdroplets in equilibrium with macroions remaining in solution. In the PDADMAC/PSSNa system, the surface tension of the supernatant was close to that of pure water, suggesting that the PSSNa-based complexes have completely sedimented, consistent with a complete liquid–solid phase separation of an out-of-equilibrium system. Besides, the high sensitivity of surface tension measurements, which can detect the presence of trace amounts of aggregates and other precursors in the supernatant, allows for very accurate determination of the exact charge stoichiometry of the complexes. Finally, the very low water/water interfacial tension that develops between the dilute phase and the denser coacervate phase in the PDADAMAC/PANa system was measured using the generalized Young–Laplace method to complete the full characterization of both systems. The overall study showed that simple surface tension measurements can be a very sensitive tool to characterize, discriminate, and better understand the formation mechanism of the different structures encountered during the formation of PECs. |
| format |
article |
| author |
Hongwei Li Martin Fauquignon Marie Haddou Christophe Schatz Jean-Paul Chapel |
| author_facet |
Hongwei Li Martin Fauquignon Marie Haddou Christophe Schatz Jean-Paul Chapel |
| author_sort |
Hongwei Li |
| title |
Interfacial Behavior of Solid- and Liquid-like Polyelectrolyte Complexes as a Function of Charge Stoichiometry |
| title_short |
Interfacial Behavior of Solid- and Liquid-like Polyelectrolyte Complexes as a Function of Charge Stoichiometry |
| title_full |
Interfacial Behavior of Solid- and Liquid-like Polyelectrolyte Complexes as a Function of Charge Stoichiometry |
| title_fullStr |
Interfacial Behavior of Solid- and Liquid-like Polyelectrolyte Complexes as a Function of Charge Stoichiometry |
| title_full_unstemmed |
Interfacial Behavior of Solid- and Liquid-like Polyelectrolyte Complexes as a Function of Charge Stoichiometry |
| title_sort |
interfacial behavior of solid- and liquid-like polyelectrolyte complexes as a function of charge stoichiometry |
| publisher |
MDPI AG |
| publishDate |
2021 |
| url |
https://doaj.org/article/cf312428dabe4a148c3f879f8f5c184e |
| work_keys_str_mv |
AT hongweili interfacialbehaviorofsolidandliquidlikepolyelectrolytecomplexesasafunctionofchargestoichiometry AT martinfauquignon interfacialbehaviorofsolidandliquidlikepolyelectrolytecomplexesasafunctionofchargestoichiometry AT mariehaddou interfacialbehaviorofsolidandliquidlikepolyelectrolytecomplexesasafunctionofchargestoichiometry AT christopheschatz interfacialbehaviorofsolidandliquidlikepolyelectrolytecomplexesasafunctionofchargestoichiometry AT jeanpaulchapel interfacialbehaviorofsolidandliquidlikepolyelectrolytecomplexesasafunctionofchargestoichiometry |
| _version_ |
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