Preparation And Study On Properties Of Nano Titanium Dioxide/Polyacrylate Core-shell Composite Emulsions

Polyacrylate latexes are widely involved in application fields, such as buildingconstruction, leather, and electron device, for its exceptional properties in transparency, filmforming, and the environment-friendly, mild reaction condition. However, there are also somedisadvantages, like weak temperature and weather endurance and poor hardness, keeping itsapplications from high performance fields. Nano-titanium dioxide, as an important modifierfor the polyacrylate latexs, can not only reinforce the comprehensive performance of thelatexs as mentioned before-temperature endurance and anti-aging performance, but also offerthe latexes some unique characteristics, for example the antisepsis due to the effect of energyabsorption of the ultraviolet. Therefore, the nano-titanium dioxide/polyacrylate hybridcomposites have attracted much attention in the academic and industrial researches.In this paper, the organic modified nano-titanium dioxide was prepared by using ethanolas solvent, γ-Aminopropyl triethoxysilane（KH-550）, γ-（2,3-epoxypropoxy）propyltrimethoxysilane（KH-560）, and γ-Methacryloxypropyl trimethoxy silane（KH-570） asmodification agents, respectively. Then the nano-titanium dioxide/P（MMA-2-EHA-AA）compound particles and the nano-titanium dioxide/acrylate latex were prepared byminiemulsion and core-shell emulsion polymerization, respectively, using modifiednano-titanium dioxide, methyl methacrylate （MMA）, butyl acrylate （BA）,2-ethylhexylacrylate （2-EHA） and acrylic acid （AA）. At the same time, the whole reaction process, thestructure and the properties of the product were studied.The main content and the results of this paper are as follows:Firstly, nano-titanium dioxide was modified by KH-550，KH-560，KH-570with thealcohol as solvent respectively and it was found that the modified effect of KH-570is the best.Then the effects of amount of KH-570, the reaction time and the reaction temperature werestudied. The result showed that the KH-570grafted successfully on the surface of the TiO₂,and the surfactant-modified rate could reach8.9%, as well as the lipophilic degree could reach56%, in the optimal modifying condition of which the amount of KH-570was15%, thereaction temperature was60℃, and the modification time was6h. The particle size and thepolydispersity index （PDI） of the modified TiO₂particles in the ethanol condition were149 and0.129narrower than that of original TiO₂particles. As expected, a homogeneous andsteady dispersion of the particles in ethanol without aggression was achieved.Secondly, the KH-570modified nano-TiO₂was used in miniemulsion polymerizationwith MMA,2-EHA and AA to prepare nano-TiO₂/P （MMA-2-EHA-AA） compound particles.And the effects of temperature, TiO₂, SDS and HD on the polymerization and its propertieswere discussed. The particles was characterized by Laser Nano-Particle size Analyzer （DLS）,Transmission Electron Microscope （TEM）, Thermo-Gravimetric Analysis （TG） andDifferential Scanning Calorimetry （DCS）. The result showed that the nano-TiO₂/P（MMA-2-EHA-AA） core-shell structure compound particles were well prepared. In additionto that, When the reaction temperature was75℃, the amount of the SDS, HD and KPS was3⁴%,2³%, and0.6wt%, respectively, the optical diameter and PDI of the particles withoutgel were achieved.Thirdly, nano-TiO₂/polyacrylate composite emulsions were directly prepared byminiemulsion polymerization and core-shell polymerization polymerization with the organicnano-TiO₂, MMA, BA,2-EHA and AA. The effects of polymerization temperature andamount of SDS, AA and nano-TiO₂were discussed. The structure and properties werecharacterized by FTIR, TEM, TG and DSL. The results showed that The nano-TiO₂/polyacrylate composite emulsions with well properties were prepared in the process ofpreparation on condition that the polymerization temperature was75⁸0℃, the amount ofSDS was5%, the amount of AA was6%, and the amount of TiO₂was1%. The best adhesiveproperties of latex were that tack （number of steel ball） was3#, and180°peel strength up to6N/m and the hold tack time was up to200h. The TEM showed that the nano-TiO₂wasencapsulated by polyacrylate, and the composite latex particles exhibited an apparentcore-shell structure.