Polymer‐TiO₂ Nanocomposites: A Route Towards Visually Transparent Broadband UV Filters and High Refractive Index Materials

Abstract

Colloids of TiO2, where rutile was the only crystal modification which could be detected, with ca. 2.5 nm average particle diameter were synthesized by hydrolysis of TiCl4 in acidic solutions. The as‐prepared particles were incorporated in polymers such as poly(vinyl alcohol) (PVAL), partially hydrolyzed poly(vinyl acetate) (PVAC88), polyvinylpyrrolidone, and poly(4‐vinylpyridine). Nanocomposites transparent in the visible range were obtained. The highest TiO2 contents in such materials were achieved with PVAL and PVAC88, with TiO2 contents of ca. 35 wt.‐% (i.e. 10.5 vol.‐%). In particular, the nanocomposites with TiO2 contents above 24 wt.‐% acted as efficient UV filters for radiation up to ca. 360 nm. At very low TiO2 contents, an absorption maximum of the embedded TiO2 particles was observed at 225 nm with an extinction coefficient of 140 000 cm−1 and a full width at half maximum of 45 nm, i.e. not only the absorption at the maximum at 225 nm but also at the flank of this band contributed significantly to the broadband UV absorption in the nanocomposites at higher TiO2 fractions. The incorporation of TiO2 enhanced the refractive index of the nanocomposites: for instance a refractive index of 1.609 was measured for a nanocomposite comprising 10.5 vol.‐% TiO2 in PVAL, compared with 1.521 for the pristine polymer. TEM image of a section of a nanocomposite of poly(vinyl alcohol) and 11 wt.‐% TiO2 (appearing dark).magnified imageTEM image of a section of a nanocomposite of poly(vinyl alcohol) and 11 wt.‐% TiO2 (appearing dark).

Optical Properties of Composites of PMMA and Surface-Modified Zincite Nanoparticles

“…55 Similar results have been reported for different particle/polymer nanocomposite systems with about 10% negative deviation from the corresponding bulk material. 61,62 We see two main reasons for such a discrepancy. The first one could be traced to the density difference between the inorganic core and the organic shell of the surface-modified ZnO nanoparticles.…”

In Vitro Assessment of Sericin-Silver Functionalized Silk Fabrics for Enhanced UV Protection and Antibacterial Properties Using Experimental Design

“…Finally, the absorption of the tested cell solution at a wavelength of 570 nm was determined. The %cell viability of the samples was calculated as Equation (5): %cell viability = OD 570e × 100 OD 570b (5) where OD 570e = the mean value of the measured optical density of the 100% extract of the test sample; OD 570b = the mean value of the measured optical density of the blank. If %cell viability >70% of blank, the sample was assumed to be non-cytotoxic.…”

“…Different types of UV protective finishes have been developed, giving excellent UV protection to textiles. Titanium dioxide and zinc oxide nanoparticles (NPs) have been widely used, as they provide protection by reflecting, scattering, or absorbing harmful UV [3][4][5]. UV protection has also been imparted to fabrics using dyes The mixture was degummed using an autoclave at 100 • C for 60 min.…”

Process Chain for the Fabrication of Nanoparticle Polymer Composites by Laser Ablation Synthesis

“…Inorganic nanoparticles dispersed in polymers as versatile and easily processible materials lead to functional nanoparticle polymer composites. In this way, optical [5][6][7], antimicrobial [8,9] or electronic properties [10,11] can be added to a conventional polymer.…”