Preparation And Study Of High Refractive Index Epoxy Organic-Inorganic Nanocomposites

Recently,high refractive index materials have attracted wide attention due to their applications in variety of optoelectronic devices.The refractive index of inorganic materials such as zirconia?ZrO₂?,titania?TiO₂?,sulfide etc.was in the range of 2.0-5.0.However,inorganic materials had limitation in the design of optical devices because of their poor processability and transparency.Epoxy with relatively low refractive index had the advantage of excellent processability,high transparency,low weight and cost.Incorporating the high refractive index into the epoxy could take advantage of the both components.In this article,ZrO₂,TiO₂and metal sulfide were fabricated into the epoxy matrix to prepare high refractive index organic-inorganic composites.Besides,the characterization and properties were also studied.Firstly,in-situ solvothermal method was used to prepare epoxy/ZrO₂nanocomposites.Silane coupling agent was introduced for the surface modification of ZrO₂.The results revealed ZrO₂ was connected with the epoxy matrix in the form of covalent bond.The nano-scale ZrO₂ particles with the size of 2-5 nm were homogeneously dispersed into the epoxy matrix without agglomeration.In the visible region,the transmittance of most of epoxy/ZrO₂ nanocomposites were above 80%.The addition of ZrO₂ enhanced refractive index of epoxy obviously.The refractive index of epoxy/ZrO₂ nanocomposites could be up to 1.73 when the content of zirconium n-propoxide was 29.58%.The glass transition temperature of the epoxy become lower with the addition of ZrO₂.Then,epoxy/TiO₂ nanocomposites was prepared in the medium of anhydride curing agent by in-situ solvothermal method.Silane coupling agent was used for the surface modification of TiO₂.The results showed TiO₂ was connected with the epoxy matrix in the form of covalent bond.The size of TiO₂ was about 80 nm.Epoxy/TiO₂ nanocomposites exhibited good transparence in the visible region.The refractive index of epoxy/TiO₂nanocomposites was increased to 1.865 when the content of Ti?OBu?₄ was50%.The decomposition temperature of epoxy/TiO₂ nanocomposites was decreased by the addition of TiO₂.Finally,two metal organic sulfide were synthesized and dispersed in the amine curing agent as the precursor to form quantum dot,and then epoxy/sulfide nanocomposites were prepared.The results displayed sulfide was homogeneously dispersed into the epoxy matrix with nanoscale.Epoxy/sulfide nanocomposites possessed excellent transparence with the transmittance of over 80%.Sulfide improved the refractive index of the epoxy sharply.When the content of CdS and ZnS was 40%and 50%,the refractive index of corresponding nanocomposites was 1.853 and 1.907,respectively.