Molecular Thermodynamic Analysis for Assessing the Relationship Between Reentrant Swelling Behavior and Ternary Liquid–Liquid Equilibrium for Poly(N-isopropylacrylamide) Nanometer-Sized Gel Particles in a Water–Tetrahydrofuran Cosolvent System

Abstract

The influence of phase separation on swelling behavior was investigated based on the thermodynamic framework of reswelling phenomena. The cloud-point for a ternary system of water(1)-tetrahydrofuran (THF)(2)-poly(N-isopropylacrylamide)(3) was examined by thermo-optical analysis (TOA). Nanometer-sized N-isopropylacrylamide (NIPA) gel particles were prepared by precipitation polymerization, and their swelling behaviors were determined using photon correlation spectroscopy (PCS). NIPA gel particles underwent reswelling when the ratio of water to THF was varied. First, the modified double lattice model (MDL) was employed to determine ternary interaction energy parameters for the liquid-liquid equilibrium (LLE) of linear poly-NIPA in a water-THF cosolvent system. The reentrant swelling equilibria of the NIPA gel in the water-THF system were then calculated using the interaction energy parameters.

Enhanced solvation effect of re-collapsing behavior for cross-linked PMMA particle gel in aqueous alcohol solutions

“…This might be attributed to the fact that MDL takes account of the effect of specific interactions such as hydrogen bonding by introducing secondary lattice term. In addition, in our previous work [24,25,27], MDL was successfully employed to calculate cononsolvency phase behavior and reentrant swelling behavior by directly applying interaction parameters from binary system. Therefore, in the further phase diagrams, MDL was used as a thermodynamic model for LLE.…”

Binary Solvent Colloids of Thermosensitive Poly(N-isopropylacrylamide) Microgel for Smart Windows

“…Comparatively, adding cosolvent is more facile to scale-up, and the existing results explicitly elucidate that cosolvents can essentially change the LCST of PNIPAAm hydrogels. 35 Nevertheless, the reported cosolvents include methanol, 36 ethanol, 37 acetone, 38 2-propanol, 39 tetrahydrofuran, 40 dimethyl sulfoxide, 41 benzaldehyde, 42 and dimethylformamide, 43 which are more volatile than water or toxic to humans, both resulting in higher requirements on the sealing of smart windows. Additionally, the influence of cosolvents on the other properties of products, such as response rate, viscosity, freezing tolerance, and recycling performance, which are all important parameters for industrialization, have been scarcely studied up to now.…”

Swelling Behaviors of Poly(N‐isopropylacrylamide) Nanosized Hydrogel Particles/Poly(vinyl alcohol)/Water Systems: Effect of the Degree of Hydrolysis of PVA

“…Freitas and co‐workers suggested an extended version of a quasi‐chemical thermodynamic model taking into account the competition between hydrogen bonding and dispersion forces. In recent studies of PNIPA gels, the swelling behaviors of the gels in ternary systems have been investigated due to intriguing phenomenon by adding various solvents in aqueous PNIPA solutions . Lian et al developed a lattice molecular thermodynamic model for describing the swelling behaviors of thermally sensitive core–shell hydrogels.…”