| Nowadays,the problems of global warming and energy shortage have become increasingly serious,which has aroused people’s great concern about the current state of the environment,energy saving,and emission reduction have become a national consensus.The energy consumed for regulating indoor climate accounts for more than 53%of the total energy consumption of buildings,and improving energy efficiency and reducing energy consumption play an increasingly important role in achieving efficient use of energy in buildings and the goal of double carbon.The energy consumed for regulating indoor climate accounts for more than 53%of the total energy consumption of buildings,and improving energy efficiency and reducing energy consumption play an increasingly important role in achieving efficient use of energy and "double carbon"goals in buildings.Thermochromic(TC)materials are currently the most ideal materials for building smart windows,which can dynamically adjust their transmittance according to the actual environmental requirements with little or no energy consumption.However,traditional TC materials have the disadvantages of low transmittance,high response temperature and small tunable spectral range.Therefore,there is an urgent need to develop TC materials with high tunable transmittance range,fast response rate and temperature sensitivity to meet the needs of smart windows.To address the above issues,this thesis starts from the design,preparation and application of fast sensitive and functional TC materials.Firstly,the mechanism of action of inorganic salt-induced dynamic reconfiguration of micelles is elucidated,and based on this,a TC hydrogel system with rapid response according to temperature is designed and developed,and an actively controlled smart window is further constructed.Secondly,composite TC materials with fast photothermal response effect are developed based on poly(isopropylacrylamide)(PNIPAM)hydrogels through nanoparticle doping with efficient photothermal conversion capability,and their energy-saving value when applied as smart windows is discussed.Finally,a novel TiO2@CsxWO3 micro-nano structure with both UV/NIR light absorption capability was developed for the purpose of spectral selective transmission modulation,and further adaptive smart windows with spectral selective transmission were obtained by synergistic interaction with PNIPAM hydrogels.The above work provides new ideas and methods for the development of more functional TC materials as well as efficient building energy-saving smart windows.The details of the research are as follows.(1)Cation-induced dynamic recon figuration of micelles for the development of novel TC hydrogel materials.The SDS micelles were investigated by combining molecular dynamics simulation(MD)and experimental methods to illustrate that the addition of K+ions can cause reconfiguration of the SDS micelle structure,resulting in significant changes in the nature,shape and size of the micelles,and that temperature change can induce a dynamic process of the micelle association/deconjugation in the mixed solution,which manifests itself macroscopically as changes in light transmission.On the basis of this,the K+/SDS hybrid system was introduced into the PAM hydrogels,and the prepared TC hydrogels were characterized by excellent tunable transmittance(ΔT550 nm=60.1%,ΔT808 nm=42.72%)and fast temperature response(t<3 min).When the prepared hydrogel is applied to the smart window by structural design,it is able to achieve a maximum temperature regulation of 12℃ in the power on/off state and has good cycling stability.The micelle-based design of TC hydrogel provides a new direction for the design of new smart windows.(2)Preparation and application of Cu7S4/PNIPAM composite hydrogel with fast photothermal response.Hollow Cu7S4,a plasmonic nanomaterial with broad spectral absorption and excellent photothermal conversion efficiency,was prepared and compounded with thermally responsive PNIPAM hydrogel to develop a Cu7S4/PNIPAM hydrogel that can passively achieve fast transmittance conversion according to photothermal response.The smart window designed by means of glass interlayer can adaptively adjust the incident light transmittance according to the realtime light intensity,thus realizing the purpose of building energy saving.The smart window has a sensitive light intensity dependence,which is transparent when the light intensity is low(T550 nm=70.2%).And when the light intensity increases,the smart window can quickly switch to a translucent state within 3 min to block more light from entering the room(T550nm=39.8%).In a test cycle,up to～16 ℃ temperature difference control of room temperature can be achieved compared to ordinary glass.At the same time,in cold climates,smart windows can deliver heat to the room through the photothermal conversion effect.The synergistic effect of efficient photo-thermal conversion materials expands new ways of utilizing traditional.TC materials.(3)Construction of spectrally selective smart windows with near-infrared(NIR)light shielding and controllable visible(Vis)light transmittance.The power density of near-infrared light in sunlight has the highest percentage(53%),and a new flower-like hollow nanomaterial with efficient UV/NIR absorption,H-T@CWOF,was prepared by structural design and combined with transparent PNIPAM hydrogel to propose a rationally designed spectrally selective smart window that achieves more than 95%shielding of near-infrared light radiation from 800 to 2500 nm,while allowing the visible light used for indoor lighting to be dynamically adjustable according to the actual ambient climate.The designed smart window can quickly accomplish dynamic switching of visible light transmittance under one solar illumination(80.2%and 46.6%at 550 nm before and after switching,respectively),and achieve a steady-state room temperature regulation of more than 20℃ compared to an ordinary glass room.Moreover,the smart window can maintain the simulated room temperature below 25℃ under the natural light irradiation,which significantly reduces the building energy consumption.In addition,the designed smart windows are characterized by fast light switching,long-term operational stability and high flexibility,which are important for the future development of green energy buildings. |
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