Study On The Preparation And Performance Of Thermochromic Matrix Composite Materials For Smart Windows

Smart window is an effective energy saving device,which can realize the effective management of outdoor solar radiation under the premise of low or no energy consumption.Thermochromic smart window is a kind of smart window equipment that utilizes thermochromic property of temperature-sensitive materials.It can realize the reversible change of sunlight transmittance under temperature change,so as to adjust the flux of sunlight radiation reversibly.Poly（N-isopropylacrylamide）（PNIPAm）hydrogel is a typical temperature-sensitive material,which is very suitable for preparing smart windows because of the great change of transmittance caused by the hydrophilic and hydrophobic changes of the polymer at about 32℃.However,32°C is obviously higher than the human body’s optimum temperature（25°C）.Therefore,PNIPAm cannot effectively regulate the solar radiation at 25℃-32℃,nor can it effectively manage the solar radiation in the whole temperature range.Therefore,it is necessary to modify PNIPAm so that it can effectively and quickly regulate the solar radiation at 25℃-32℃.The research purpose of this paper is to develop two kinds of electro-thermal dual-response smart windows based on PNIPAm hydrogel material,so that the PNIPAm based smart window can realize the solar radiation management in the full temperature range.The specific research content of this paper mainly includes the following two parts:In the first part,we used the electrothermal properties of silver nanowire-polyethylene terephthalate（Ag NW-PET）conductive film to compensate for the deficiency of solar modulation performance of PNIPAm hydrogel at 25℃-32℃.Specifically,Ag NW-PET film with excellent electrothermal conversion performance was made into a double-layer electrothermal mold and was energized with FTO conductive glass on both sides,and PNIPAm precursor solution is injected into the mold to react to form Ag NW-PET/PNIPAm/Ag NW-PET multilayer smart window equipment.When the temperature is below 25℃or higher than 32℃,due to the PNIPAm hydrogel can realize own cause the color characteristics,it does not need to been exerted applied voltage;when the temperature is between 25℃and 32℃,PNIPAm hydrogel could not realize its thermochromic properties.Therefore,the smart window device was applied voltage to heat the Ag NW-PET film with PNIPAm hydrogel to actively promote its color change.Finally,the experimental results show that the smart window can effectively manage the solar radiation at 25℃-32℃under a relatively low applied voltage,and the solar modulation ability(ΔT_sol)can reach 19.67%under the applied voltage of 5 V.In the second part,we found that FTO conductive glass only used for conducting in the first part also has excellent conductive performance,so we tried to simplify Ag NW-PET/PNIPAm/Ag NW-PET multi-layer smart window equipment.The electro-thermal conversion performance of FTO was directly utilized to compensate for the deficiency of solar modulation performance of PNIPAm hydrogel at 25℃-32℃.Specifically,FTO glass was directly made into a double-layer electric heating mold,and PNIPAm precursor solution was injected into the mold for reaction to form FTO/PNIPAm/FTO three-layer smart window equipment.The modulation mechanism of the smart window is similar to the modulation performance of the above-mentioned Ag NW-PET/PNIPAm/Ag NW-PET multi-layer smart window,only the discoloration of the PNIPAm hydrogel driven by the Ag NW/PET electrothermal conversion is simplified to the direct electrothermal conversion drives the discoloration of the PNIPAm hydrogel by the FTO.Finally,the experimental results show that the intelligent equipment than the Ag NW-PET/PNIPAm/Ag NW-PET multi-layer smart window device has more excellent ability of solar radiation management and under 5 V voltage applied,the solar modulation performance(ΔT_sol)can reach 26.51%.In the third part,we modified the PNIPAm hydrogel in the second part by introducing polyacrylamide（PAM）which can improve the flexibility of PNIPAm and graphene oxide（GO）with local surface plasmonic resonance（LSPR）properties.An FTO/PNIPAm-PAM/GO/FTO photoelectrothermal multi-response smart window was fabricated.Compared with the previous two kinds of smart windows,the performance of the smart window has been greatly improved,and the smart window under the applied voltage of 4 V can show the advantages of rapid response and excellent solar modulation ability.In summary,this paper designed two kinds of photoelectrothermal multi-response smart windows and one kind of electro-thermal multi-response smart window equipment around PNIPAm hydrogel,all of which show excellent application potential.