Preparation And Structure Properties Of Silicone Microspheres And Light Diffusing Materials

LED(light-emitting diode abbreviation)can be used as an efficient solid-state illumination,which has many merits such as small size,low power consumption,long life,high brightness,low heat generating,eco-friendly.It is the third-generation illumintaion that can be widely used.However,the traditional LED illumintaion source is often glare and high directivity.When it directly acts as an indoor illumination,it will cause strong irritation and damage human eyes.Light diffusing materials with high haze are needed to soft the light and eliminate glare.However,light diffusing materials will reduce the transmittance while increasing the haze,resulting sacrifice of illumination brightness.High-performance light diffusing materials can combine high transmittance and high haze.Therefore,the preparation of higher performance light diffusing materials has important practical significance.The refractive index and particle size of the light-diffusing particles are the main factors affecting the light transmittance and haze of the light-diffusing material.In this paper,phenyltrimethoxysilane(PTMS),methyltrimethoxysilane(MTMS),vinyltrimethoxysilane(VTMS)were used as raw materials,and ammonia water was used as a catalyst.Inspired by the insect compound eye microlens array,the strawberry-like silicone microsphere light diffusing particles with surfaceadsorption of polystyrene nanoparticles were prepared by electrostatic self-assembly method.Further,the light diffusing particles were used to prepare light diffusing materials through mixing with polycarbonate(PC)or polymethyl methacrylate(PMMA)via extrusion blending process.And the light diffusing materials was moulded into a disc with thickness of 2 mm and diameter of 30 mm by injection molding process.Or a light diffusing film with thickness of 0.2 mm was prepared by casting polydimethylsiloxane(PDMS)mixing with strawberry-like silicone microspheres as light diffusing agent.The structure and properties of light diffusing materials were systematically characterized and analyzed.The effects of light diffusing particle size,relative refractive index and surface structure on light diffusing properties were studied in detail.The morphology and surface electrical properties of the microspheres were characterized and analyzed by optical microscopy(OM),scanning electron microscopy(SEM)and Zeta potential test.The composition and structure of the microspheres were characterized by infrared spectrometer(FTIR).The thermal properties of the light diffusing particles and the light diffusing materials were investigated by differential scanning calorimetry(DSC)and thermogravimetric analyzer(TGA).Their light diffusing properties were tested by a light transmittance haze tester.The following main conclusions are summarized:(1)By changing the amount of catalyst added,poly(vinyltrimethoxysilane)microspheres with particle size distribution from 1 μm to 5 μm were prepared;By adjusting the ratio of phenyltrimethoxysilane and methyltrimethoxysilane,copolymerized microspheres having a refractive index distribution from 1.4319 to 1.5612 were prepared.The analysis of the transmittance and haze of the PC light diffusing material shows that the effect of the particle size of the microspheres on the optical properties of the light diffusing material is greater than the effect of the refractive index of the microspheres.(2)Copolymer microspheres with particle size of 2 μm and refractive indices of 1.4319 and 1.5315,respectively,were added to PMMA with a refractive index of 1.49 to prepare light-diffusing materials,and the transmittance and haze were measured and analyzed.When the refractive index of the microsphere is smaller than the refractive index of the substrate,the optical performance of corresponding light diffusing material is more excellent.The same conclusion was obtained by adding copolymerized microspheres having a refractive index of 1.5315 to PC or PMMA which having refractive indices of 1.57 and 1.49,respectively to prepare light diffusing materals.(3)The positively charged polystyrene nano spheres were uniformly adsorbed on the surface of the polyvinylsilsesquioxane microspheres by electrostatic self-assembly to form strawberry-like light diffusing particles.The prepared light diffusing particles were further added to polydimethylsiloxane(PDMS)to prepare a light diffusing film with thickness of 0.2 mm.The results show that the addition of this new type of light diffusing particles can better reduce back reflection,improve transmittance,and greatly improve the optical performance of the light diffusing film.The prepared film has transmittance of 93% and haze of 99.2%.