Coupled Deswelling of Multiresponse Microgels

Abstract

In this article, we study the response of a thermosensitive and ionic microgel to various external stimuli where coupling between different contributions to the total osmotic pressure is needed to describe the observations. We introduce a new Flory solvency parameter chi ( T, Q, n) with strong dependence on the network charge, Q, and salt concentration, n. The scaling exponent for the salt-induced deswelling of the microgel is the signature of the coupling between the mixing and ionic osmotic pressures.

Influence of network topology on the swelling of polyelectrolyte nanogels

“…Particularly, for the network with z = 4, one can see that while the nanogel radius R g remains constant for low values of the dissociation fraction, it displays a decreasing behavior for f = 0.5, which is in agreement with the behavior predicted by the theory of Ref. 16 , and also observed in experiments 24,28,29,32,45,46 and in a previous simulation study 11 . We note that even though excluded volume effects are taken into account in our model, we are not able to observe a reentrant (or re-swelling) behavior expected for high salt concentrations 35,47 .…”

Use of Environmental Scanning Electron Microscopy to image poly(N-isopropylacrylamide) microgel particles

“…Particle size is temperature and pH dependent. The diameter decreases with increasing temperature and also when pH decreases, because the charge diminishes under these conditions [37,39]. For the system presented in this work the diameter is around two micron for basic pH and low T. For pH $ 6 and a temperature above 60°C, the size measured by PCS is around 300 nm.…”

“…More information can be found in [26]. The synthesis of the systems used in this work follows the procedure described by Crowther and Vincent [36], and more specific details can be found in our previous works [33][34][35]37]. …”

“…N,N-methylene bisacrylamide (4.1% BA) is the cross-linker and 4,4 0 -azobis (4-cyanopentanoic acid) (8.2% ACPA) the initiator [36][37][38]. Solid content in weight was 0.07%.…”

“…Several studies have focused on NIPAM-co-AAc microgels [37,[39][40][41]. Particle size is temperature and pH dependent.…”