Yulu Zhang

One-step sol–gel preparation of PDMS–silica ORMOSILs as environment-resistant and crack-free thick antireflective coatings

Polydimethylsiloxane (PDMS)–silica ORMOSIL (organically modified silicate) sols were prepared by a one-pot sol–gel process using tetraethyl orthosilicate as an inorganic precursor and hydroxyl-terminated PDMS as an organic modifier, and antireflective (AR) coatings were prepared with these sols by dip coating. It was found that the addition of PDMS to silica sols significantly increased the viscosity and the controllable viscosity range of the silica sols, affording us a simple route to prepare very thick AR coatings with controlled thickness by a single deposition step. The coated fused silica substrates retained very high transmission of up to 99.9% at a determined wavelength. The addition of PDMS to the silica sols improved the hydrophobicity and abrasion-resistance of the coating, and prevented to some extent the coating from cracking which occurred in a pure inorganic thick AR coating. The PDMS–silica ORMOSIL AR coatings are stable after standing for 2 months at room temperature in an environment of 95% relative humidity. The relationship between structure and properties of the coatings is discussed considering the particle growth mechanism.

Sol–gel silica antireflective coating with enhanced abrasion-resistance using polypropylene glycol as porogen

Abstract Silica antireflective (AR) coatings with high transmittance and enhanced abrasion-resistance were synthesized by sol–gel process using polypropylene glycol (PPG) as porogen. The effects of molecular weight of PPG and weight ratio of PPG to SiO2 on the refractive index and abrasion-resistance of the coating were systematically studied and compared with those of polyethylene glycol (PEG). Experimental data showed that the refractive index decreased with increasing the weight ratio to SiO2 and molecular weight of both PEG and PPG, but PPG was much more effective than PEG. In the case of same molecular weight, PPG modified coating has the higher porosity than PEG modified one. When the weight ratio of PPG to SiO2 is in a low level, the PPG-containing silica AR coatings exhibit the good abrasion-resistance. PPG is liquid at room temperature and the better solubility than PEG. These effective and economic AR coatings with enhanced abrasion-resistance have potential value in the field of solar thermal collectors.

Preparation of porous silica films in a binary template system for double-layer broadband antireflective coatings

Porous silica films with a refractive index varying from 1.44 to 1.15 were prepared and applied to realize a double-layer broadband AR coating. The porous silica films were obtained using tetraethylorthosilicate (TEOS) as precursor and a binary template as porogen which was composed of cetyltrimethylammonium bromide (CTAB) and polypropylene glycol (PPG). The molar ratio of the two templates was optimized, and a hypothetical mechanism for the cooperative assembly of silicates with the binary template system was proposed. The two layers had the same skeleton despite different porosity with the top layer much more porous than the bottom one. The double-layer double-wavelength AR coating had excellent optical properties with transmittances of 99.6% and 99.8% at 532 nm and 1064 nm, respectively.

Biodegradable poly(ethylene glycol)–poly(ε-carprolactone) polymeric micelles with different tailored topological amphiphilies for doxorubicin (DOX) drug delivery

Three poly(ethylene glycol)–poly(e-carprolactone) (PEG–PCL) copolymers with different topologies but identical molar ratio between PEG to PCL were designed. These copolymers, namely, diblock (L-PEG–PCL), triblock (B-PEG–PCL), and star shaped (S-PEG–PCL) copolymers, were extensively characterized by 1H Nuclear Magnetic Resonance (1H NMR), Fourier Transform Infrared Spectroscopy (FTIR), and Gel Permeation Chromatography (GPC) analyses. The effect of topology on crystallization was investigated by X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC). Results showed that the diblock copolymer possessed the highest crystallinity, followed by triblock and star shaped copolymers. Although the topology did not affect the self-assembly behavior of copolymers, the effects on size, size distribution, drug loading content, and drug release rate of the polymeric micelles were observed. The micelles self-assembled from linear diblock copolymer achieved higher cellular uptake and lower half maximal inhibitory concentration (IC50). These findings are favorable to establish the foundation to further design proper structure of amphiphilic copolymers as nanocarrier systems for efficient anticancer therapy.

Design and Preparation of SiO 2 /TiO 2 /SiO 2 -TiO 2 Antireflective Coatings with Excellent Abrasion-resistance and Transmittance via Sol-Gel Process: Design and Preparation of SiO 2 /TiO 2 /SiO 2 -TiO 2 Antireflective Coatings with Excellent Abrasion-resistance and Transmittance via Sol-Gel Process

通过膜层设计理论设计出以K9玻璃为基底的兼具高透过率和高耐摩擦性的三层宽带增透膜, 并通过溶胶-凝胶技术成功制备了所设计的增透膜. 以正硅酸乙酯(TEOS)和钛酸丁酯(TTIP)为前驱体、以盐酸为催化剂制得SiO 2 和TiO 2 溶胶. 将两种溶胶按一定比例混合得到SiO 2 -TiO 2 复合溶胶. 实验结果表明: 三层增透膜在可见光区的平均透过率达到98.7%, 与未镀膜的K9玻璃基片相比提高了7.1%. 增透膜经较强机械摩擦后透过率基本保持不变, 表明该增透膜具有优良的耐摩擦性. 采用六甲基二硅氮烷(HMDS)对增透膜表面进行进一步的修饰, 修饰后增透膜与水的接触角提高至94.3°, 增透膜的疏水性及环境稳定性得到较大的提高.通过膜层设计理论设计出以K9玻璃为基底的兼具高透过率和高耐摩擦性的三层宽带增透膜, 并通过溶胶-凝胶技术成功制备了所设计的增透膜. 以正硅酸乙酯(TEOS)和钛酸丁酯(TTIP)为前驱体、以盐酸为催化剂制得SiO 2 和TiO 2 溶胶. 将两种溶胶按一定比例混合得到SiO 2 -TiO 2 复合溶胶. 实验结果表明: 三层增透膜在可见光区的平均透过率达到98.7%, 与未镀膜的K9玻璃基片相比提高了7.1%. 增透膜经较强机械摩擦后透过率基本保持不变, 表明该增透膜具有优良的耐摩擦性. 采用六甲基二硅氮烷(HMDS)对增透膜表面进行进一步的修饰, 修饰后增透膜与水的接触角提高至94.3°, 增透膜的疏水性及环境稳定性得到较大的提高.