Transparent Hybrid Thin Films Research Articles

Fabrication of photo-crosslinkable polymer/silica sol–gel hybrid thin films as versatile barrier films

Versatile films composed of a photo-crosslinkable thiol-ene (ThE)/silica sol–gel hybrid nanocomposite were prepared using a two-step process. Tetrafunctional thiol and triene monomers were employed as precursors to generate a matrix polymer. Tetraethyl orthosilicate (TEOS) was incorporated as the silica source for the sol–gel process. A two-step process, sol–gel reaction followed by photocuring, resulted in uniform and transparent hybrid thin films. The formation of homogeneous, mechanically stable, and optically transparent films was confirmed and the films were characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses. The morphological properties of the films were assessed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The thermal expansion of the obtained membrane films was examined by thermomechanical analysis (TMA). In addition, optical transmission and gas permeation were assessed for high-performance applications.

ホスフィンオキシドを有するシルセスキオキサンとユーロピウム錯体との配位型ハイブリッドの作製

A phosphorescent coordination hybrid has been successfully prepared from silsesquioxane containing phosphine oxide and europium tris β-diketonate. The novel silsesquioxane was synthesized by the sol-gel reaction of corresponding trialkoxysilane obtained by the ene-thiol reaction of allyldipenylphosphine oxide and mercaptopropyltriethoxysilane. Despite the high concentration of the europium complex (50 wt%), the complex was dispersed completely into the silsesquioxane, giving a dense, homogeneous, and transparent hybrid thin film. The luminescence property of this film was also investigated. This hybrid thin film with the embedded europium complex shows bright phosphorescence accompanied with a characteristic sharp spectrum derived from the f-f transition of europium at ambient temperature. It can be concluded that the enhancement of the emission intensity and the branching ratio for the europium complex in the hybrid compared to the europium complex in PMMA is due to the formation of a coordination bond between the europium complex and the phosphine oxide in silsesquioxane.

Sol-Gel Fabrication of Low Temperature Organic-Inorganic Hybrid Film Patterns for Photonic Applications

Titania/organically modified silane hybrid thin films for photonic applications were prepared by combining a low temperature sol-gel technique and a spin-coating process from an organic-inorganic hybrid system. Effects of the titanium content and heat treatment temperature on the structural and optical properties of the hybrid thin films were characterized by atomic force microscopy and UV-visible spectroscopy. It is found that the optical and microstructural properties of the hybrid thin films depend on the heat-treatment temperature and titanium molar contents. The thickness and the refractive index of the hybrid thin films were also measured and found to be related to the heat treatment temperature and titanium molar content. These results indicate that a dense and high transparent hybrid thin film can be obtained at a low heat treatment temperature. Potential photonic device structural patterns can easily fabricated from the as-prepared hybrid thin films by using etching process.

Antibacterial Thin Films on Glass Substrate by Sol–Gel Process

Submitted June 16, 2006; Accepted October 16, 2006 Antibacterial transparent thin films, containing different amounts of silver ion, have been prepared on a glass substrate by the sol–gel process. Thin films were obtained from inorganicorganic hybrid sols derived from 3-(glicydiloxypropyl)trimethoxy silane, N-(2-aminoethyl)3-aminopropyl-trimethoxysilane and aluminium-sec-butoxide/ethylaceto-acetate complex and doped with silver ions. The films were characterized by Scanning Electron Microscopy and Raman Spectroscopy. The physical properties of the films were studied by solar-box, taber abraser, hardness test pencil, scratch-adhesion test and spectroscopy. The antibacterial activity of the coatings were investigated against gram negative Escherichia coli and gram positive Staphylococcus aureus. The results showed that 1% doping of the transparent hybrid thin film with silver ions resulted in high antibacterial properties of the film.

Synthesis and Optical Properties of Soluble Polyimide/Titania Hybrid Thin Films

AbstractSummary: In this study high‐refractive‐index polyimide/titania hybrid optical thin films were successfully prepared using a sol‐gel process combined with spin coating and multistep baking. The hybrid thin films were prepared from a soluble polyimide, a coupling agent, and a titania precursor. Transparent hybrid thin films can be obtained at TiO2 content as high as 40 wt.‐%. The FE‐SEM results suggest that the TiO2 particles in the hybrid thin films have diameters in the nanometer range. The thermal decomposition temperatures of the prepared hybrid materials are above those of the respective polyimide except for the highest TiO2 content hybrids. The refractive indices at 633 nm of the prepared hybrid thin films increase linearly from 1.66 to 1.82 with increasing TiO2 content. The excellent optical transparency, thermal stability, and tunable refractive index provide the potentials of the polyimide/titania hybrid thin films in optical applications. magnified image

Synthesis and characterization of polyimide/oligomeric methylsilsesquioxane hybrid films

AbstractIn this study, polyimide/silsesquioxane hybrid materials were synthesized from aminoalkoxysilane‐capped poly(pyromellitic dianhydride‐co‐4,4′‐oxydianiline) (PMDA‐ODA) and oligomeric methylsilsesquioxane (O‐MSSQ) precursors. The O‐MSSQ moiety was used to obtain well characterized nano‐inorganic cage and network structures in the hybrid materials. The effects of molecular structures and composition on the morphologies and properties of the prepared hybrid materials were studied. The phase separation of the prepared hybrid materials could be controlled by varying the molecular weight of the polyimide moiety, the SiOH end group content of the O‐MSSQ or the coupling agent. Homogeneous and transparent hybrid thin films were obtained from the low molecular weight polyimide moiety with a coupling agent, 3‐aminopropyltrimethoxysilane (APrTMS). However, microphase separation occurred if the molecular weight of the polyimide moiety was enhanced or was prepared without a coupling agent, as evidenced by atomic force microscopy (AFM), field emission scanning electron microscopy (FE‐SEM), and electron spectroscopy for chemical analysis (ESCA). The high SiOH content of the O‐MSSQ could enhance the bonding density between the organic and inorganic moiety and thus retard phase separation. The thermal and mechanical properties of the prepared hybrid materials were largely improved compared with the parent polyimide, PMDA‐ODA, and were demonstrated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and thermal‐stress analysis. The hybrid materials showed adjustable refractive index and dielectric constant by varying the O‐MSSQ content. The birefringence of the PMDA‐ODA was reduced by incorporating the O‐MSSQ moiety. This work revealed that the polyimide/O‐MSSQ hybrid materials could have potential applications as optical films or low dielectric constant materials. Copyright © 2004 Society of Chemical Industry

Synthesis and Optical Properties of Poly(BPDA-ODA)/Silica Hybrid Thin Films

Poly(BPDA-ODA)/silica hybrid optical thin films were synthesized using a sol-gel reaction combined with spin coating and multi-step baking. The hybrid thin films were prepared by the precursors of aminoalkoxysilane capped poly(BPDA-ODA) amic acid and tetramethoxysilane (TMOS). Highly transparent hybrid thin films were obtained at a silica content of 0–51.9 wt%. The prepared hybrid thin films showed homogeneous structures and excellent surface planarity. The refractive index of the prepared hybrid thin films decreased linearly with increasing the silica content while the Abbe number showed the opposite trend. The prepared hybrid films also exhibited a much smaller optical birefringence than the parent poly(BPDA-ODA) because of the reduction of the rigid backbone by incorporating the silica moiety. Optical planar waveguides were prepared from the prepared hybrid thin films. The optical losses of the planar waveguides at 1310 nm were in the range of 0.5–1.3 dB/cm, which were reduced significantly by increasing the silica moiety. The reduction of the C–H bonding density and excellent surface planarity by incorporating the silica moiety explain the trend of optical loss. These results suggest that the prepared polyimide-silica hybrid thin films have potential applications for optical devices.

Synthesis and Optical Properties of Polyimide-Silica Hybrid Thin Films

In this study, two series of the polyimide−silica hybrid optical thin films, PMDA−ODA/SiO2 and 6FDA−ODA/SiO2, were synthesized using an in situ sol−gel reaction combined with spin coating and multistep curing. The hybrid thin films were prepared by the aminoalkoxysilane-capped poly(amic acid)s and tetramethoxysilane (TMOS) as the precursors. Highly transparent hybrid thin films were obtained at a silica content as high as 54.9 wt %. The FE-SEM study suggests the nanosize domain of the silica moieties in the hybrid thin films. The AFM study demonstrates that the hybrid thin films have excellent planarity. The prepared hybrid thin films show good thermal stability. The refractive indices of the prepared hybrid thin films decrease linearly with increasing silica content while the Abbe number of the hybrid thin films shows the opposite trend. The birefringence of the prepared polyimide−silica hybrid thin films is reduced by incorporating the silica moiety. Optical planar waveguides were prepared from the prepared hybrid thin films using a thermal oxide as the cladding layer. The optical losses of these planar waveguides at 1310 nm are in the range of 0.5−1.9 dB/cm, which are due to the higher harmonics of the aromatic C−H vibration, the O−H vibration, and the extrinsic loss. The optical losses of the prepared polyimide−silica hybrid films are lower than their parent polyimdes and thus have potential applications in optical devices.

Luminescence properties of transparent hybrid thin film covalently linked with lanthanide complexes

Novel hybrid thin films covalently doped with Eu 3+ (Tb 3+) have been prepared via direct routes involving co-condensation of tetraethoxysilane and phen-Si in the presence of Eu 3+ (Tb 3+) by spin-casting and their luminescence properties have been investigated in detail. Lanthanide ions can be sensitized by anchored phenanthroline in hybrid thin films. Excitation at the ligand absorption wavelength (272 nm) resulted in the strong emission of the lanthanide ions i.e. Eu 3+ 5D 0– 7F J ( J=0, 1, 2, 3, 4) emission lines and Tb 3+ 5D 4– 7F J ( J=6, 5, 4, 3) due to the energy transfer from the ligands to the lanthanide ions.