scholarly journals Stabilizing effect of TMAO on globular PNIPAM states: preferential attraction induces preferential hydration

2016 ◽  
Vol 18 (46) ◽  
pp. 31459-31470 ◽  
Author(s):  
Martin A. Schroer ◽  
Julian Michalowsky ◽  
Birgit Fischer ◽  
Jens Smiatek ◽  
Gerhard Grübel

We study the effect of the organic co-solute trimethylamine N-oxide (TMAO) on the volume phase transition of microgel particles made from poly(N-isopropylacrylamide) (PNIPAM) using dynamic light scattering (DLS) and all-atom molecular dynamics (MD) simulations.

Soft Matter ◽  
2017 ◽  
Vol 13 (30) ◽  
pp. 5185-5193 ◽  
Author(s):  
Valentina Nigro ◽  
Roberta Angelini ◽  
Monica Bertoldo ◽  
Fabio Bruni ◽  
Maria Antonietta Ricci ◽  
...  

Microgel suspensions of an Interpenetrated Polymer Network (IPN) of PNIPAM and PAAc in D2O have been investigated through dynamic light scattering as a function of temperature, pH and concentration across the Volume Phase Transition (VPT).


2017 ◽  
Vol 19 (25) ◽  
pp. 16541-16554 ◽  
Author(s):  
Fernando Rodríguez-Díaz ◽  
Aly Castellanos-Suárez ◽  
Aileen Lozsán

A phenomenological insight into the volume transition of microgel particles via nematic-like ordering behavior through solvation processes of a polymer matrix.


2000 ◽  
Vol 151 (1) ◽  
pp. 521-527 ◽  
Author(s):  
A. Fernández-Nieves ◽  
A. Fernández-Barbero ◽  
F.J. De las Nieves

Soft Matter ◽  
2022 ◽  
Author(s):  
Ekaterina Ponomareva ◽  
Ben Tadgell ◽  
Marco Hildebrandt ◽  
Marcel Krüsmann ◽  
Sylvain Prevost ◽  
...  

Thermoresponsive microgels undergo a volume phase transition from a swollen state under good solvent conditions to a collapsed state under poor solvent conditions. The most prominent examples of such responsive...


2021 ◽  
Author(s):  
Dongdong Lu ◽  
Mingning Zhu ◽  
Jing Jin ◽  
Brian R. Saunders

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)...


Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 42
Author(s):  
Simon Friesen ◽  
Yvonne Hannappel ◽  
Sergej Kakorin ◽  
Thomas Hellweg

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.


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

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