Binary Solvent Colloids of Thermosensitive Poly(N‑isopropylacrylamide) Microgel for Smart Windows

• Published in: Industrial & engineering chemistry research Vol. 53; no. 48; pp. 18462 - 18472
• Main Authors: Wang, Mi, Gao, Yanfeng, Cao, Chuanxiang, Chen, Kaimin, Wen, Yicun, Fang, Dingye, Li, Li, Guo, Xuhong
• Format: Journal Article
• Language: English
• Published: American Chemical Society 03.12.2014
• Subjects: Alcohols; Colloids; Glycerols; Microgels; Modulation; Solvents; Thermosensitive; Windows (intervals)
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie502828b

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 increasing N,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.