Combining Krafft Point and Volume Phase Transition Temperature Toward Regulation of Solar Radiation and Privacy Protection

Abstract

temperature, electricity, and optics have been studied and produced SWs. [4][5][6][7][8] Ordinarily, visible light (380-780 nm) can, in principle, be used to illuminate a room, reducing the need for interior lighting and saving more energy. Near-infrared light (NIR, 780-2500 nm) is predominantly responsible to heat up spaces. The control of transparency/color is the key to the conventional SWs that could adjust the light transmission and achieve energy savings.In fact, SWs have unique characteristics in the aspect of working principles, operation conditions, and performance. Among the studied SWs materials, unlike the electrochromic and photochromic SWs with additional energy requirements for triggering solar radiation modulation, the thermo-responsive SWs exhibit passive strategies and self-regulating ability in response to temperature variation, [9,10] whose automatic response to temperature cut down the need for switch systems and holds promise for industrial production and ease of implementation.Energy-saving and privacy are the key functionalities of next-generation thermo-responsive SWs, most of them can turn opaque to resist solar irradiation at daytime (higher environmental temperature) for energy-saving purposes, [11][12][13] meanwhile some SWs play the role of privacy protection by keeping opaque at night (lower environmental temperature). [14][15][16] There has been little research intended to integrate reduction of the solar irradiation and privacy protection, which the combination process may destroy the respective characteristics without rational design. Fortunately, prior empirical studies proved that this integration can be achieved. [17][18][19] Wang prepared dual-response hydrogels with both lower critical solution temperature (LCST) and upper critical temperature (UCST) based on cellulose-grafted polymers. [17] Gao developed a kind of mineralized supramolecular hydrogels via a simple bio-inspired physical cross-link process between amorphous CaCO 3 and poly(acrylic acid). [18] In our previous work, [19] the cationic-anionic surfactant systems were used as SWs to achieve an opacity-transparency-opacity transition as temperature changes with the adjustable switch temperatures in a wide range. However, an independent and fine adjustment on the two switch points is still to be overcome due to the mutual effect of the T k of cationic surfactant and Everlasting pursuit of high energy efficiency as well as meeting fluctuant temperatures raise various lighting requirements, which is driving the originality of thermochromic smart windows (SWs). SWs with dual-temperature response upon rational designs are identified as an effective approach to regulate solar radiation and protect privacy. Here, combining the Krafft point (T k ) of ionic surfactants and the volume phase transition temperature (VPTT) of gels toward SW materials is utilized to achieve a transition of opacity-transparence-opacity as temperature change, maintaining transparency at an intermediate temperature range with favorable optical modul...

Integrated Thermoelectric Design Inspired by Ionic Liquid Microemulsion-Based Gel with Regulatable Dual-Temperature Responsiveness

“…Meanwhile, this disadvantage can be overcome by utilizing ionic surfactants in the construction of gel materials. Ionic surfactants will precipitate from the transparent micelles to make the gel opaque when the temperature is lower than its Kraft point, which intelligently realizes the goal of privacy protection. , Further, by utilizing low-temperature responsive Kraft point and high-temperature responsive cloud point or PNIPAM simultaneously, dual-temperature responsive gel materials can be prepared, possessing both energy-saving and privacy-protection functions. Even so, it is not suitable to introduce inorganic salts to the above surfactant-based gels for fabricating thermoelectric dual-responsive smart windows because the electrostatic interaction of inorganic salts on ionic surfactants and the salting-out effect on nonionic surfactants will influence the morphology of aggregates or cause the surfactants to precipitate, resulting in the loss of thermochromic function.…”