scholarly journals The effect of saccharides on equilibrium swelling of thermo-responsive gels

RSC Advances ◽  
2020 ◽  
Vol 10 (51) ◽  
pp. 30723-30733
Author(s):  
A. D. Drozdov ◽  
J. deClaville Christiansen
Keyword(s):  
Phase Transition ◽  
Aqueous Solutions ◽  
Mechanical Response ◽  
Volume Phase Transition ◽  
Volume Phase ◽  
Equilibrium Swelling ◽  
Responsive Gels

A model is developed for the mechanical response and equilibrium swelling of thermo-responsive gels and applied to the analysis of their volume phase transition in aqueous solutions of saccharides.

Necklace-like microstructure in shallow-quenched aqueous solutions of poly(n-isopropylacrylamide), detected by advanced small-angle neutron scattering methods

Soft Matter ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 671-682 ◽  
Author(s):  
Satoshi Koizumi ◽  
Masahiko Annaka ◽  
Dietmar Schwahn
Keyword(s):  
Phase Transition ◽  
Aqueous Solutions ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Volume Phase Transition ◽  
Volume Phase ◽  
Isopropyl Acrylamide

The microstructure of aqueous poly(N-isopropyl acrylamide) (PNIPA) gel and solution was investigated by small-angle neutron scattering (SANS) in the vicinity of the gel volume phase transition at TV (= 34 °C).

scholarly journals Equilibrium swelling of thermo-responsive copolymer microgels

RSC Advances ◽  
2020 ◽  
Vol 10 (70) ◽  
pp. 42718-42732
Author(s):  
A. D. Drozdov ◽  
J. deClaville Christiansen
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Molar Fraction ◽  
Volume Phase Transition ◽  
Volume Phase ◽  
Volume Phase Transition Temperature ◽  
Equilibrium Swelling ◽  
Copolymer Gels ◽  
Copolymer Microgels

A model is developed for equilibrium swelling of thermo-responsive copolymer gels and is applied to predict the effect of molar fraction of comonomers on the volume phase transition temperature of macroscopic gels and microgels.

Triply-responsive OEG-based microgels and hydrogels: Regulation of swelling ratio, volume phase transition temperatures and mechanical properties

2021 ◽  
Author(s):  
Dongdong Lu ◽  
Mingning Zhu ◽  
Jing Jin ◽  
Brian R. Saunders
Keyword(s):  
Phase Transition ◽  
Biomedical Engineering ◽  
Volume Phase Transition ◽  
Swelling Ratio ◽  
Transition Temperatures ◽  
Ph Responsive ◽  
Network Systems ◽  
Volume Phase ◽  
Phase Transition Temperatures ◽  
Volume Swelling

Thermally- and pH-responsive microgels (MGs) and hydrogels are fascinating network systems that have been applied in biomedical engineering and sensing. The volume-swelling ratio (Q) and the volume-phase transition temperatures (VPTTs)...

scholarly journals Accounting for Cooperativity in the Thermotropic Volume Phase Transition of Smart Microgels

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 42
Author(s):  
Simon Friesen ◽  
Yvonne Hannappel ◽  
Sergej Kakorin ◽  
Thomas Hellweg
Keyword(s):  
Phase Transition ◽  
Interaction Parameter ◽  
Quantitative Description ◽  
Water Molecules ◽  
Volume Phase Transition ◽  
Network Chain ◽  
Solvent Interaction ◽  
Volume Phase ◽  
The Cross ◽  
Interaction Parameter Χ

A full quantitative description of the swelling of smart microgels is still problematic in many cases. The original approach of Flory and Huggins for the monomer–solvent interaction parameter χ cannot be applied to some microgels. The reason for this obviously is that the cross-linking enhances the cooperativity of the volume phase transitions, since all meshes of the network are mechanically coupled. This was ignored in previous approaches, arguing with distinct transition temperatures for different meshes to describe the continuous character of the transition of microgels. Here, we adjust the swelling curves of a series of smart microgels using the Flory–Rehner description, where the polymer–solvent interaction parameter χ is modeled by a Hill-like equation for a cooperative thermotropic transition. This leads to a very good description of all measured microgel swelling curves and yields the physically meaningful Hill parameter ν. A linear decrease of ν is found with increasing concentration of the cross-linker N,N′-methylenebisacrylamide in the microgel particles p(NIPAM), p(NNPAM), and p(NIPMAM). The linearity suggests that the Hill parameter ν corresponds to the number of water molecules per network chain that cooperatively leave the chain at the volume phase transition. Driven by entropy, ν water molecules of the solvate become cooperatively “free” and leave the polymer network.

Influence of volume phase transition phenomena on the behavior of hydrogel-based valves

2004 ◽  
Vol 99 (2-3) ◽  
pp. 451-458 ◽  
Author(s):  
Andreas Richter ◽  
Steffen Howitz ◽  
Dirk Kuckling ◽  
Karl-Friedrich Arndt
Keyword(s):  
Phase Transition ◽  
Volume Phase Transition ◽  
Volume Phase
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