Transparent photo‐curable co‐polyacrylate/silica nanocomposites prepared by sol‐gel process

Abstract

This work prepared the highly transparent photo-curable co-polyacrylate/silica nanocomposites by using sol-gel process. The FTIR and 13 C NMR analyses indicated that during the sol-gel process, the hybrid precursors transform into composites containing nanometer-scale silica particles and crosslinked esters/anhydrides. Transmission electron microscopy (TEM) revealed that the silica particles within the average size of 11.5 nm uniformly distributed in the nanocomposite specimen containing about 10 wt % of Si. The nanocomposite specimens exhibited satisfactory thermal stability that they had 5% weight loss decomposition temperatures higher than 1508C and coefficient of thermal expansion (CTE) less than 35 ppm/8C. Analysis via derivative thermogravimetry (DTG) indicated that the crosslinked esters/anhydrides might influence the thermal stability of nanocomposite samples. The UV-visible spectroscopy indicated that the nanocomposite resins possess transmittance higher than 80% in visible light region. Permeability test revealed a higher moisture permeation resistance for nanocomposite samples, which indicated that the implantation of nano-scale silica particles in polymer matrix forms effective barrier to moisture penetration. Adhesion test of nanocomposite samples on glass substrate showed at least twofold improvement of adhesion strength compared with oligomer. This evidenced that the silica and the hydrophilic segments in nanocomposite resins might form interchains hydrogen bonds with the À ÀOH groups on the surface of glass so the substantial enhancement of adhesion strength could be achieved.

Physics and Chemistry of Sol-Gel Nanocomposites Formation

“…Thus, photo-curable polyacrylate nanocomposite with silica gel nanoparticles is prepared by sol-gel synthesis. In contrast to the ordinary sol-gel process (using water for liquid), in this work hydrolysis of the precursor was conducted through air moisture in order to confine size of silica gel nanoparticles to nanometer scale and protect the composite from residual water molecules [277]. Morphology of crystals in polyurethane cast films (PU) with different gold particles content 0.1, 0.3 and 1.0 % is studied (Fig.…”

Effect of UV Curing on Electrical Properties of a UV‐Curable co‐Polyacrylate/Silica Nanocomposite as a Transparent Encapsulation Resin for Device Packaging

“…[9][10][11] Inappropriate UV curing deteriorates the mechanical properties [12] and electrical properties [13,14] of polymeric resins. In the previous studies, we reported the preparation and property characterizations of transparent, UV-curable co-polyacrylate/ silica nanocomposite resins [15] and it has been successfully applied to the direct encapsulation of a bottom-emitting OLED. [16] In this work, a systematic study on the effects of UV curing and post-baking treatments on the electrical properties of such a nanocomposite sealing resins is presented.…”

“…[15] The ingredients of nanocomposite resins were the oligomer (bisphenol A epoxy diacrylate, see Figure 1 for its chemical structure) purchased from Sartomer Co., the radical photopolymerization initiator (1-hydroxycyclohexylphenyl ketone) obtained from Chembridge International Co., acrylic acid and tetraethyl orthosilica (TEOS) purchased from Aldrich Chemicals Co. Preparation of nanocomposite resin is briefly described as follows.…”

“…a) The inorganic content in nanocomposite identified via TGA was about 11.12 wt.-%. [15] analyzer in conjunction with a probe station. The dielectric properties of samples, e and tand, were measured by a C-V system (Keithley, 82-DOS) or an HP 4194A impedance analyzer operating at a frequency of 1 MHz.…”

“…Nevertheless, significant deterioration of thermal stability was observed in the nanocomposite specimens subjected to UV curing at high energy density, e.g., the T 5%WL decreased from 175.9 to 161.7 8C when UV curing energy density was raised from 4.75 to 19 J Á cm À2 . Owing to the existence of newly formed small molecules such as ethyl acrylate or acrylic anhydride in nanocomposite resin, [15] the DTG curves of nanocomposite resin consist of one major peak at about 430 Á C and one broad peak at around 190 Á C as shown in Figure 6 Table 3. Absorbance ratio of designated functional groups in Figure 5.…”