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Significance Statement
This new kind of “smart window” from a thermosensitive microgel can block out heat when the outside temperatures rise. It could one day help consumers better conserve energy on hot days and reduce electric bills.
Journal Reference
Industrial & Engineering Chemistry Research, 2014; 53 (48): 18462.
Mi Wang †‡, Yanfeng Gao *‡§, Chuanxiang Cao ‡, Kaimin Chen *∥, Yicun Wen †,Dingye Fang †, Li Li †, and Xuhong Guo*†⊥
ABSTRACT
Thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) microgel colloids were prepared by using water and high-boiling alcohol as binary solvent. Their thermosensitive behavior and solar modulation ability were studied by differential scanning calorimetery, ultraviolet–visible–near-infrared spectrophotometery, dynamic light scattering, and rheology. Effects of alcohol content and cross-linker dose on their microstructures and optical properties were investigated. A model house was constructed to test their energy-saving performance in smart windows. It was found that the solar modulation ability of PNIPAAm microgel colloids decreased with increasingN,N′-methylenebis(acrylamide) (BIS) dose or alcohol content. Compared to glycol, glycerol showed better compatibility with PNIPAAm hydrogels, inducing less deterioration of the solar modulation ability. With 0.1 wt % (of NIPA) BIS, when glycerol was added as a cosolvent, the prepared PNIPAAm microgel colloids exhibited spherical morphology, controllable LCST, short response time, suitable viscosity, low freezing point, restrained evaporation rate, and excellent energy-saving performance, which makes them much better candidates for application in smart windows than those using a single solvent.
