In situ Generation of Au Nanoparticles in UV-curable Refractive Index Controlled SiO₂−TiO₂−PEO Hybrid Films

Abstract

UV-curable inorganic (SiO 2 -TiO 2 )-organic (polyetheylene oxide [PEO]) hybrid films with high refractive index (RI) values were synthesized, and Au nanoparticles were generated in situ inside such hybrid films. The hybrid films and the corresponding Au-doped films were prepared from sols derived from a mixture of silicon, titanium, and organically modified silicon alkoxides and gold chloride following a sol-gel dip-coating method. An equivalent SiO 2 /TiO 2 /PEO/Au molar ratio (nominal) of 27.7:46.1:23.0:3.2 was maintained in the sol. UV treatments of the dried (90 °C) films with energies from 5.3 ( 0.1 to 53.0 ( 0.5 J cm -2 resulted in densification with a gradual increase of the RI value up to 1.75. Drying and UV treatments of the corresponding HAuCl 4 -incorporated hybrid films induced generation of Au nanoparticles and showed the characteristic Au-plasmon peak. A gradual red-shifting of the Au-plasmon band from 545 to 571 nm was observed with respect to the UV-treatment energies. This red-shifting is initially due to the increase of RI of the film, and in the later stages it is mainly due to the Au-plasmon coupling concurrently with the slight increase of RI values. Transmision electron microscopy of the UV-treated films showed the presence of densely populated Au nanoparticles of mainly 4-5 nm in size inside the hybrid SiO 2 -TiO 2 -PEO film matrix.

Optical Properties of Hybrid Organic‐Inorganic Materials and their Applications

“…In the case of composite materials, basically two approaches can be found, either in situ synthesis of metal nanostructures in the matrix using chemical, thermal or photoinduced reductions; or incorporation of nanoparticles colloidal dispersions during the matrix preparation. The matrix can typically be inorganic, [496][497][498][499] sol-gel based matrix [215,[500][501][502][503][504][505][506][507][508][509][510] or polymers. [511][512][513][514] Regarding the in situ growth, the main drawbacks are the limitations in terms of control of the shape of the particles, which are often spherical or wire-type structures and the homogeneity in size and dispersion.…”

Syntheses of novel photosensitive polysiloxanes and their effects on properties of UV-cured epoxy methacrylate coatings

“…1 Based on the advantages of high efficiency, low-energy consumption, and reduced pollution, studies of UV-curing systems have succeeded in uncovering new aspects and building toward significant achievements. [2][3][4][5] Acrylate and methacrylate groups have been employed widely for UV photopolymerization because of their strong reactivity, showing rapid, near-complete conversions (i.e., no residual unreacted monomers) with low heat generation. 6 Customarily, the main types of monomers/ prepolymers used in UV-curable systems are epoxy acrylate, 7,8 urethane acrylate, 9 unsaturated polyesters, 10,11 and polyether acrylate.…”

“…Many silicon components have been applied to non-UV curing systems, while there are only several types incorporated into the UV-curable, such as organosilicone-containing hybrid systems [13][14][15] and inorganicorganic silicon hybrid. 3,5,16,17 Those used silicon components still do not seem to present large numbers of photosensitive groups or more efficiently enhance the properties of UV-cured coatings. Polysiloxanes are capable not only of providing two sites for crosslinks, but also of forming functional chains through bond formation with silicon.…”

Tuning of Ag-SPR band position in refractive index controlled inorganic-organic hybrid SiO2-PEO-TiO2 films

“…[1][2][3][4][5][6][7] These coatings can also be decorated with different colours using the noble metal nanoparticles as colouring sources. [8][9][10] Very recently we described a simple yet much improved technology for the development of inorganic-organic hybrid nanocomposite sols applicable for making hard and abrasion resistant coatings curable at low temperature (<100°C) on plastic substrates. 4,5,11 The incorporation of Au 8 and Ag 9 nanoparticles inside the inorganic-organic hybrid matrices could produce uniform colouration arising from the SPR absorption of embedded nanoparticles.…”

“…We have also shown plasmon coupling of Au nanoparticles embedded in a SiO 2 -PEO-TiO 2 hybrid film matrix leading to the shifting of Au plasmon bands with respect to the UV treatment energies. 10 Previously, we have successfully tailored the surface plasmon absorption positions of Au and Ag nanoparticles by tuning the RI of the embedding dielectric films (SiO 2 , SiO 2 -TiO 2 13 and SiO 2 -ZrO 2 14,15 ) applicable for glass substrates. These films were prepared after heat-treatment of the doped films at high temperatures (500-800°C).…”