Thermoresponsive polycations

Abstract

Aqueous solutions of polyelectrolytes are known to be complex, however, when the charged polymer carries a simple counterion as sodium or chloride it is usually soluble in water. By modifying...

Versatile Agar‐Zwitterion Hybrid Hydrogels for Temperature Self‐Sensing and Electro‐Responsive Actuation

“…The mechanism of the temperature self‐sensing behavior of Agar/PSBMA can be explained by the dipole–dipole interaction and electrostatic interaction between oppositely charged ionic groups (Figure 4e). [ 32 ] Since PSBMA carries both positive and negative charges, inter‐ and intra‐chain electrostatic interactions are formed below UCST, exhibiting opaque properties due to phase separation. When it is heated above UCST, the electrostatic self‐association between zwitterionic chains is overcome, and water molecules are inserted between the chains, making the disordered structure and the solubility of PSBMA in water, so it appears optically transparent macroscopically.…”

Multi-tunable thermoresponsive behaviors of poly(amido thioether)s

“…This phenomenon was different from that observed in phase transition related to traditional LCST-type polymers, in which the light scattering intensity usually tended to increase with temperature increment in the LCST region. 7–18 The abnormal behavior possibly originated from efficient transitions among different types of amide- and imidazolyl-related HBs upon heating, and the aggregation behavior was not pronounced. As the temperature further increased, F ( T )/ F (10 °C) and MCR values first jumped to the maximum and then decreased.…”

“…1–15 As a class of smart polymers with temperature-dependent solubility, TRPs can undergo intriguing phase transition at the lower critical solution temperature (LCST) and/or upper critical solution temperature (UCST). 7–18 Owing to variations of the hydrophilic/hydrophobic ratio and mutual interactions ( e.g. , hydrogen bonding (HB) and electrostatic/dipole–dipole interactions), the thermoresponsivity can be affected by some factors involving the chemical composition, molar mass, molecular weight distribution, branching structure, and topology.…”

Thermoresponsive ionogels

“…These interactions induce the polymer chains towards self-aggregation, driving the polymer to a super-collapsed, nonconjugated state. 85 At sufficiently elevated temperatures (above the UCST), the polymer chains become wholly solvated and separated due to the disruption of dipole–dipole interactions. The two discernible conformations of these amphiphilic brushes mainly diverge in their overarching wettability.…”

“…86 Conversely, when the polymers exist in a non-conjugated state, they present decreased hydrophilicity as water morphs into an unfavorable solvent, resulting in reduced polymer swelling. 85 However, it is worth noting that the degree of polymer hydrophilicity remains lower than that seen in their unattached state. The principle of dipole–dipole self-association is postulated for all amphiphilic polymers, but not all manifest UCST behavior.…”