Solvent‐ and counterion‐specific swelling behavior of poly(acrylic acid) gels

Abstract

The collapse of alkali metal poly(acrylate) (PAAM) gels was investigated for various water/organic solvent mixture systems: methanol (MeOH), ethanol (EtOH), 2-propanol (2PrOH), t-butanol (tBuOH), dimethyl sulfoxide (DMSO), acetonitrile (AcN), acetone, tetrahydrofuran (THF), and dioxane. In order to ascertain the counterion specificity in the swelling behavior, four kinds of alkali metal counterions were used: Li ϩ , Na ϩ , K ϩ , and Cs ϩ . Remarkable solvent and counterion specificities were observed for every counterion species and every solvent system, respectively. For example, in aqueous EtOH the dielectric constants (D cr ) at which collapse occurred were in the order PAACs Ͻ PAALi Ͻ PAAK Ͻ PAANa. On the other hand, the D cr at which PAALi gel collapsed increased in the order tBuOH Ͻ dioxane Ͻ THF Ͻ MeOH Ͻ 2PrOH Ͻ EtOH Ͻ acetone Ͻ AcN Ͻ DMSO, where the D cr ranged from about 39 to about 67. This was in contrast to our previous observation for a partially quaternized poly(4-vinyl pyridine) (P4VP) gel, which collapsed in a much narrower D cr region in similar mixed solvents. The present solvent-and counterion-specific collapses are discussed on the basis of solvent properties such as the dielectric constant and Gutmann's donor number and acceptor number of a pure solvent.

Interaction between Covalent DNA Gels and a Cationic Surfactant

“…This is because normal micellization involves counterion binding to neutralize the charge of the micelle, while binding of surfactant to the DNA network involves the release of counterions. In accordance with this, a cac of 0.02 mM was found and this is in excellent agreement with cac values for CTAB in solution with DNA as obtained by other methods. −

3 Dependence of relative volume ( V / V 0 ) of DNA gels (1% cross-linker density) on CTAB concentration. The plateau from [CTAB] = 0 mM to [CTAB] = 0.02 mM (=cac) is also represented in detail (see inset).

…”

Interaction between Covalent DNA Gels and a Cationic Surfactant

“…This is because normal micellization involves counterion binding to neutralize the charge of the micelle, while binding of surfactant to the DNA network involves the release of counterions. In accordance with this, a cac of 0.02 mM was found and this is in excellent agreement with cac values for CTAB in solution with DNA as obtained by other methods. −

3 Dependence of relative volume ( V / V 0 ) of DNA gels (1% cross-linker density) on CTAB concentration. The plateau from [CTAB] = 0 mM to [CTAB] = 0.02 mM (=cac) is also represented in detail (see inset).

…”

Bioinspired ultra-stretchable and anti-freezing conductive hydrogel fibers with ordered and reversible polymer chain alignment

“…A similar phase transition was observed for covalently crosslinked PAAS hydrogels swelled by water/DMSO mixture 37 . The addition of DMSO into water causes significant desolvation of PAAS chains upon the counterion Na + binding carboxylate groups, increasing the polymer–polymer interactions and triggering the phase transition 37 . The optimal solution for PAH fiber preparation has DMSO% = 20 wt%, which is very close to the critical DMSO concentration for the phase transition.…”

“…In the step-strain measurements (Fig. 2c ), the optimal PAAS solution exhibits a fast and complete recovery to its initial modulus, which indicates a great reversibility due to the fast alignment and relaxation of PAAS chains in the physical gel 37 . As shown in Fig.…”

Conditions Leading to Polyelectrolyte Complex Overcharging in Solution: Complexation of Poly(acrylate) Anion with Poly(allylammonium) Cation

“…Interestingly, quite similar osmotic coefficients of potassium and lithium PA were obtained, 60 whereas the herein reported aggregation experiments suggest stronger binding of smaller Li + cation. The more recent investigations of polyelectrolyte gel collapse in mixed solvents (water containing alcohols, DMSO, acetone, THF) 61,62 are also in accord with osmometric results. However, the above experiments were made in mixed solvents and involve cross-linked polymers, which can affect the counterion−polyion preferences considerably.…”

Interaction between Covalent DNA Gels and a Cationic Surfactant

“…This is because normal micellization involves counterion binding to neutralize the charge of the micelle, while binding of surfactant to the DNA network involves the release of counterions. In accordance with this, a cac of 0.02 mM was found and this is in excellent agreement with cac values for CTAB in solution with DNA as obtained by other methods. −

3 Dependence of relative volume ( V / V 0 ) of DNA gels (1% cross-linker density) on CTAB concentration. The plateau from [CTAB] = 0 mM to [CTAB] = 0.02 mM (=cac) is also represented in detail (see inset).

…”

Bioinspired ultra-stretchable and anti-freezing conductive hydrogel fibers with ordered and reversible polymer chain alignment

“…A similar phase transition was observed for covalently crosslinked PAAS hydrogels swelled by water/DMSO mixture 37 . The addition of DMSO into water causes significant desolvation of PAAS chains upon the counterion Na + binding carboxylate groups, increasing the polymer–polymer interactions and triggering the phase transition 37 . The optimal solution for PAH fiber preparation has DMSO% = 20 wt%, which is very close to the critical DMSO concentration for the phase transition.…”

“…In the step-strain measurements (Fig. 2c ), the optimal PAAS solution exhibits a fast and complete recovery to its initial modulus, which indicates a great reversibility due to the fast alignment and relaxation of PAAS chains in the physical gel 37 . As shown in Fig.…”

Conditions Leading to Polyelectrolyte Complex Overcharging in Solution: Complexation of Poly(acrylate) Anion with Poly(allylammonium) Cation

“…Interestingly, quite similar osmotic coefficients of potassium and lithium PA were obtained, 60 whereas the herein reported aggregation experiments suggest stronger binding of smaller Li + cation. The more recent investigations of polyelectrolyte gel collapse in mixed solvents (water containing alcohols, DMSO, acetone, THF) 61,62 are also in accord with osmometric results. However, the above experiments were made in mixed solvents and involve cross-linked polymers, which can affect the counterion−polyion preferences considerably.…”

Interaction between Covalent DNA Gels and a Cationic Surfactant

“…This is because normal micellization involves counterion binding to neutralize the charge of the micelle, while binding of surfactant to the DNA network involves the release of counterions. In accordance with this, a cac of 0.02 mM was found and this is in excellent agreement with cac values for CTAB in solution with DNA as obtained by other methods. −

3 Dependence of relative volume ( V / V 0 ) of DNA gels (1% cross-linker density) on CTAB concentration. The plateau from [CTAB] = 0 mM to [CTAB] = 0.02 mM (=cac) is also represented in detail (see inset).

…”

Bioinspired ultra-stretchable and anti-freezing conductive hydrogel fibers with ordered and reversible polymer chain alignment

“…A similar phase transition was observed for covalently crosslinked PAAS hydrogels swelled by water/DMSO mixture 37 . The addition of DMSO into water causes significant desolvation of PAAS chains upon the counterion Na + binding carboxylate groups, increasing the polymer–polymer interactions and triggering the phase transition 37 . The optimal solution for PAH fiber preparation has DMSO% = 20 wt%, which is very close to the critical DMSO concentration for the phase transition.…”

“…In the step-strain measurements (Fig. 2c ), the optimal PAAS solution exhibits a fast and complete recovery to its initial modulus, which indicates a great reversibility due to the fast alignment and relaxation of PAAS chains in the physical gel 37 . As shown in Fig.…”

Conditions Leading to Polyelectrolyte Complex Overcharging in Solution: Complexation of Poly(acrylate) Anion with Poly(allylammonium) Cation

“…Interestingly, quite similar osmotic coefficients of potassium and lithium PA were obtained, 60 whereas the herein reported aggregation experiments suggest stronger binding of smaller Li + cation. The more recent investigations of polyelectrolyte gel collapse in mixed solvents (water containing alcohols, DMSO, acetone, THF) 61,62 are also in accord with osmometric results. However, the above experiments were made in mixed solvents and involve cross-linked polymers, which can affect the counterion−polyion preferences considerably.…”