Preparation And Properties Of Polysiloxane/Vanadium Dioxide Composite Film With Enhanced IR-adjustment

VO2 is a typical material with good thermal phase transition characteristics.It can be widely used in intelligent window materials.The crystal structure of VO2 is monoclinic(M phase)when its transition temperature(Tc)is higher than room temperature.IR light and visible light have higher transmittance,and thus,room temperature is gradually increased as light enters.However,the crystal structure of VO2 becomes tetragonal rutile(R phase)when its transition temperature is lower than room temperature.The transmittance of visible light remains constant,whereas the transmittance of IR light evidently reduced.Consequently,heat generated by IR light cannot enter the room.There are three major problems need to be resolved about VO2 thin film.Firstly,the integral transmittance of the visible region of VO2 thin film is too low to meet the requirements of glass lighting.Secondly,the solar modulation capability(?Tsol)of VO2 film is too low to meet the demand for intelligent temperature control.Thirdly,the VO2 thin film is unstable and it is easy to be oxided by the oxidizing gas in the air,losing the solar regulation ability.In view of the three main problems of VO2 thin film,we have mainly completed the study of three systems in this paper:(1)the fabrication and study of vanadium Dioxide film with the functions of intelligent temperature control and superhydrophobicity.(2)The fabrication and study of superhydrophobic polysiloxane film with highly transparent and self-cleaning.(3)The fabrication and study of polysiloxane/vanadium dioxide composite films with enhanced infrared light regulation performance.(1)The fabrication and study of vanadium dioxide film with the functions of intelligent temperature control and super hydrophilic.The vanadium dioxide film(VO2)with the functions of intelligent temperature control and super hydrophilic was fabricated using sol-gel method.The VO2 thin film had higher visible transmittance and solar modulation capability while acids added as colloidal dispersant,and the polyvinyl pyrrolidone(PVP)as solubilizer during the preparation of VO2 precursor solution.Samples were characterized by XRD?SEM?XPS?GA?FTIR?AFM and UV-3600.The results showed that the VO2 film which was fabricated by adding 1 ml hydrochloric acid(pH=1)and 0.2 g PVP into the precursor solution had the best quality and the visible transmittance and solar modulation capability were greatly increased.High-purity M/R phase VO2 films were prepared under different kinds of VO2 precursor solution which was adding different kinds of acids.The valence states of vanadium in VO2 thin films prepared under different acidic conditions were mainly 4+,and high purity M/R phase VO2 thin films were prepared.It can be found that purity VO2(M/R)films were prepared under different acidic conditions by combined with XRD pattern,XPS pattern and Raman pattern.As shown by the results of water contact angle measurement and surface roughness test,the VO2 thin films prepared under different acidic conditions all had small surface average roughness,and all the surface roughness were less than 18 nm.All the films showed good hydrophilicity.(2)The fabrication and study of super hydrophobic polysiloxane film with highly transparent and self-cleaning.This paper investigates preparation of highly transparence,self-cleaning and superhydrophobic polysiloxane thin film by sol-gel method.Superhydrophobic thin film was obtained by using silane coupling agents via a two-step acid-base catalysis mechanism.The hydrophobicity of polysiloxane film fabricated under different silane modifiers.The static water contact angle of polysiloxane film was 156° when the modifier was methyltrimethoxysilane.We reported the effects of one experimental parameters:acid catalyzed hydrolysis time on water contact angles.The superhydrophobic polysiloxane film fabricated while the acid hydrolysis time was more than 1 h.Then we explored the effects of film thickness on surface hydrophobicity and transmittance.The static water contact angle of the polysiloxane thin film was 156°,while spin-coated three layers.The integral transmittance of the visible region of polysiloxane thin film was higher 85%,with good visible light transmittance.Finally,the water-impact resistance of polysiloxane thin film was studied.The hydrophobic angles of polysiloxane thin film was still higher than 150° after 12-hour water droplet impact under certain conditions,showing a better water-impact resistance.(3)The fabrication and study of polysiloxane/vanadium dioxide composite film with enhanced infrared light regulation performance.Intelligent temperature control,self-cleaning,and superhydrophobic nanostructured polysiloxane/vanadium dioxide composite film had been successfully fabricated using the sol-gel method.These composite films are composed of an underlying infrared(IR)-regulating VO2 layer and a top layer that is completely deposited with protective nano-sized polysiloxane particles.Experimental results showed that the composite structure adding PVP and hydrochloric acid to the precursor solution enhanced the IR light regulation performance,anti-oxidation,anti-acid,and hydrophobicity of VO2 film.The solar modulation capability of VO2 film was enhanced to 8.3%.Meanwhile,the composite structure has good thermal stability in terms of IR regulation.