Preparation and characterization of thermoresponsive poly(N‐isopropylacrylamide‐co‐N‐isopropylmethacrylamide) hydrogel materials for smart windows

Abstract

In this study, a series of thermoresponsive cross-linked copolymer poly [N-isopropylacrylamide(NIPAm)-coN -isopropylmethacrylamide(NIPMAm)] (P-M series samples: P-M-0, 10, 20, 30, 40, where numbers are co-monomer contents) hydrogels were prepared by free radical polymerization using the main monomer N-isopropylacrylamide (NIPAm), co-monomer N-isopropylmethacrylamide (NIPMAm), cross-linking agent N, N-methylenebisacrylamide, initiator (ammonium persulfate)/catalyst, and solvent water. In addition, a series of samples [P-G series samples: P-G-0, 10, 20, 30, 40, where numbers are co-solvent glycerol content) were prepared using P-M-40 as components and water/cosolvent glycerol as a mixed solvent. The effects of co-monomer NIPMAm and co-solvent glycerol contents on the lower critical solution temperature (LCST)/ freezing temperature and light transmittance as function of temperature of the prepared copolymer gels were investigated. The resulting thermoresponsive polymer gels had LCSTs in the range of 17.9 to 38.7 C and freezing points in the range of 6.3 to −38.5 C. These gels are suitable materials for smart windows that are responsive to various environmental conditions.

Nanocellulose-based hydrogels for drug delivery

“…PNIPAM hydrogels have a phase transition temperature of about 32 1C, which approaches the human body temperature. 158,159 Under the LCST, PNIPAM is relatively dispersed and the polymer chains remain hydrophilic. When the temperature rises above the LCST, the PNIPAM undergoes a reversible coil-to-globule transition in water, due to the increasing hydrophobic interaction.…”

Surface-Active Thermally Responsive Hydrogels by Emulsion Sedimentation for Smart Window Applications

“…For example, using the glycerol additive, Jang et al reported thermally responsive PNIPA-based polymer gels with LCST in the range of 17.9−38.7 °C. 15 Glycerol has also been used to change the transition temperature of the HPC solution-based smart window. 35 Phase transition temperature in the range of 21−30 °C has been reported for HPC-AAm hydrogels using CaCl 2 as an additive.…”

Thermoresponsive Polymers for Water Treatment and Collection

“…Above the LCST, the polymer is hydrophobic and is insoluble in water, as revealed by the aqueous solution opacity . PNIPAm-based materials have been used for generating clean water because of their superior ability to collect and rapidly release water under natural sunlight or moderate electrical heating . This unique feature has inherent attributes toward developing sustainable techniques to treat wastewater streams or collect water from the atmosphere (Figure B).…”

“…29 PNIPAm-based materials have been used for generating clean water because of their superior ability to collect and rapidly release water under natural sunlight or moderate electrical heating. 30 This unique feature has inherent attributes toward developing sustainable techniques to treat wastewater streams or collect water from the atmosphere (Figure 1B). Inspired by these ideas, remarkable efforts have been made to design thermoresponsive materials in the form of brushes, microgels, and hydrogels.…”