Preparation Of TiO₂/polyacrylate Composite Coating And Its Surface Micronization Properties

The decorative materials of traditional building exterior walls,such as glass curtain walls and ceramic tiles,are affected by the construction technology of the realy weight of materials,and there are many problems such as light pollution,increased building weight,and safety.Building exterior wall coatings,by contrast,have many advantages such as simple construction process,multiple options convenient maintenance and doing they not only can protect the exterior walls but also beautify the appearance which have become the current mainstream decoration materials for buildings.At present,building exterior wall coatings generally have the disadvantages of poor weather resistance and contamination resistance,discolorate and shedding affect the aesthetics of buildings and reduce their service life.Therefore,to improve adhesion,weathering resistance,and stain resistance is a high-performance exterior wall coatings should be developed.One of the effective measures is to develop a new exterior wall coating by material design,such as preparing polymer with photocatalytic degradation performance and using it as the main film-forming material.The self-cleaning function could effectively avoid the contamination and discoloration extend service life,indicate exterior wall coating can be tracked according to the degree of micronization,and the defects can be repaired or re-brushing to reduce the later maintenance and maintenance costs of the coating.Nano-TiO₂ has unique advantages in the design and synthesis of photocatalytic degradation polymers.In this thesis,anatase-type nano-TiO₂ particles are prepared by a non-aqueous sol-gel method,and the compatibility letween TiO₂ and polymer is improved by surfactant,which modify the surface of the TiO₂ particles.Nano-TiO₂ /polyacrylate composite emulsion is prepared,the composite emulsion shows good micronization performance under ultraviolet irradiation after film formation.Besides,black phosphorus modifies nano-TiO₂ and then prepare phosphorus doping nano-TiO₂ /polyacrylate composite emulsion.It is found that the polymer degradation rate of doping nano-TiO₂ is faster than before modification.The details work content are as follows:(1)The non-aqueous sol-gel method is used to prepare anatase-type nano-TiO₂ particles,and the TiO₂ particles can be well dispersed in water,whose particle size is5-20 nm.Subsequently,the surfactant sodium dodecyl sulfate(SDS)is used to modify TiO₂ particles,and then Zeta potential is changed from a+44.7 mV to-30.9mV.The stretching vibration peak of S=O and bending vibration(outward)peak of C-H can be found in FTIR spectrum.The thermogravimetric curve shows that the modified nano-TiO₂ presents a greater mass loss during the test.These results indicate that the nano-TiO₂ is successfully modified by SDS.(2)Nano-TiO₂/polyacrylate composite latex is prepared by seed semi-continuous emulsion polymerization,and its photocatalytic degradation and surface micronization properties are investigated.According to TEM image nano-TiO₂ particles uniformly disperse in the polymer matrix.The X-ray diffraction energy spectrum analysis(EDS)characterization shows that the Tielement is uniformly fractionated in the composite film.The thermogravimetric curve indicate that the thermal stability has been significantly improved.The results of differential scanning calorimetry(DSC)indicate that the Tg temperature is inversely proportional to the content of nano-TiO₂ .It can be seen from the SEM image the surface of the composite film after ultraviolet light indicate the phenomenon of micronization.The GPC test show that the average molecular weight of polymer film in composite film decreases obviously,which indicates that nano-TiO₂ can promote the degradetion of the polymer.(3)In order to decrease the high recombination rate of electron-hole pairs,BP is introduced to modify the nano-TiO₂.Through ultrasound to prepare P doping nano-TiO₂ in the dispersion.After modification,P doping nano-TiO₂ has a stronger diffraction peak intensity,and the half peak,as displayed in the XRD pattern,which indicate that its crystallinity has been improved.The infrared spectrum shows that new peaks of P-O-Tiappear after modification.P doping nano-TiO₂/polyacrylate composite emulsion is prepared by the emulsion blending method.According to the EDS,Tiand P elements are evenly disperseing in the composite film.The thermal stability of the composite film is improve,which indicate from TG curve.SEM and GPC results exhibit the photodegradation of polymer.When the phosphorus is doped to nano-TiO₂,the rate of degradetion is faster than the substance without P at same light condition.