Highly Scattering Hierarchical Porous Polymer Microspheres with a High-Refractive Index Inorganic Surface for a Soft-Focus Effect

Abstract

Functional light scattering materials have received considerable attention in various fields including cosmetics and optics. However, a conventional approach based on optically active inorganic materials requires considerable synthetic effort and complicated dispersion processes for special refractive materials. Here, we report a simple and effective fabrication strategy for highly scattering hierarchical porous polymer microspheres with a high-refractive index inorganic surface that mitigates the disadvantages of inorganic materials, producing organic-inorganic hybrid particles with an excellent soft-focus effect. Hierarchical organic-inorganic hybrid particles were synthesized using the simple physical mixing of porous poly (methyl methacrylate) (PMMA) microparticles with different pore sizes and regularities as the organic core and titanium dioxide (TiO2) nanoparticles with different particle sizes as the inorganic shell. The polar noncovalent interactions between polar PMMA microspheres and the polar surface of TiO2 nanoparticles could induce the hierarchical core-shell structure of hybrid particles. The synthesized hybrid particles had increased diffuse reflectance properties of up to 160% compared with single inorganic particles. In addition, the light scattering efficiency and soft-focus effect could be increased further, depending on the size of the TiO2 nanoparticles and the pore characteristics of the PMMA microspheres. The proposed study can provide a facile and versatile way to improve the light scattering performance for potential cosmetics.

Hierarchical Porous Polymer Coatings Based on UV-Curing for Highly Efficient Passive All-Day Radiative Cooling

“…The excellent R̅ sun and the angle-independent reflectance can be ascribed to the hierarchical porous structure. First, the moderate porosity and the refractive index ( n ) difference between polymer matrix ( n ≈ 1.5) and air voids ( n = 1), together provide an efficient light scattering ability. , As a comparison, the dense poly­(TMPTA) coating has low R̅ sun of ∼0.09 (Figure S7a). Second, the continuous nano- to microscale pores ranging from ∼200 nm to ∼8 μm (Figure e), lead to multiple reflection via a dramatically prolonged dissipation route .…”

Synthesis of LiDAR-Detectable True Black Core/Shell Nanomaterial and Its Practical Use in LiDAR Applications

“…Owing to the high specific surface area of the CSNs, the 140 nm SBT CSN-based paint showed the highest R% value. The NIR reflectance of the SBT CSNs can be attributed to the synergistic effects of their high specific surface area and porous nature and the difference in the refractive indices of the SiO 2 core and TiO 2 shell, which resulted in light reflection and scattering in the NIR region [ 18 , 45 ]. Previous studies have reported that the light reflectivity of core/shell or bilayered materials increases with an increase in the difference in the refractive indices of the constituent materials.…”

Facile Control of Structured ZnO Polymeric Nanoparticles through Miniemulsion Polymerization: Kinetic and UV Shielding Effects

“…Aside from particle sizes and the location of ZnO NPs laying on the surface or in the shell of ZPPs, the absorbance and absorption patterns of Pickering-like and hollow ZPPs are comparable. Multiple light scattering, between the high refractive index of ZnO NPs (1.9596) at the interface and the low refractive index of the PS core for Pickering-like ZPPs or the air void (1.0003) for hollow ZPPs, is possibly the major contributor for their shielding properties [ 48 ].…”