Ionic liquid modulation of swelling and LCST behavior of N-isopropylacrylamide polymer gels

Poly(ionic liquid) thermo-responsive hydrogel microfluidic actuators

“…These novel devices are now becoming more reminiscent of biological units than conventional silicon micromachined components. Examples include the microfluidic integration of a variety of stimuli-responsive materials that respond to changes in their external environment, such as temperature, light, pH, or variations in electrical potential and pressure [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] . Among them, one of the most studied stimuli-responsive hydrogels is poly(N-isopropyl acrylamide) (pNiPAAm), due to its lower critical solution temperature (LCST) behaviour in the presence of an aqueous medium 20,[33][34][35] .…”

Fluidic flow delay by ionogel passive pumps in microfluidic paper-based analytical devices

“…Both ionogels are porous and able to accommodate larger volumes of water. Nevertheless the Dicyanamide anion of the IL of IO-2 strongly bonds with water molecules as demonstrated by Gallagher et al [24].…”

Poly(Ionic Liquid) Semi-Interpenetrating Network Multi-Responsive Hydrogels

“…Stimuli-responsive polymers are defined as polymers that exhibit a conformation change in a reliable, reproducible and useful manner when exposed to a variation in their external environment [ 1 , 2 ]. Many types of stimuli can be employed, including temperature, pressure, magnetic and electric field, lighting conditions, pH and the presence of other chemical species in their local medium [ 1 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Hydrogels comprise a particularly interesting class of stimuli-responsive materials due to their biomimetic nature [ 6 ].…”

“…Hydrogels comprise a particularly interesting class of stimuli-responsive materials due to their biomimetic nature [ 6 ]. These materials are crosslinked polymer networks that absorb large quantities of water and, when under the influence of specific stimuli, change their water absorption properties, which in turn translate into a hydrogel volume variation [ 7 , 14 ]. Extensively studied examples of such materials include N -isopropylacrylamide (NiPAAm) hydrogels, which possess a well-documented thermally induced shrinking behaviour associated with a lower critical solution temperature (LCST) at ca.…”

“…Extensively studied examples of such materials include N -isopropylacrylamide (NiPAAm) hydrogels, which possess a well-documented thermally induced shrinking behaviour associated with a lower critical solution temperature (LCST) at ca. 32–35 °C [ 4 , 5 , 9 , 12 , 13 , 14 , 15 , 21 , 22 , 23 , 24 ]. This behaviour is a result of a thermodynamically driven equilibrium shift from the strongly hydrated form defined by solution-polymer interactions to a much more compact form dominated by polymer-polymer interactions.…”