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hujinyang木虫 (正式写手)
炙天
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[求助]
做过二氧化硅基杂化玻璃的请进，求指导。 已有1人参与
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我之前是学有机的，现在要做一些二氧化硅基的玻璃，看了一下文献，大多是用溶胶凝胶法制备的，现在有两种方法，一是直接物理共混，二是共价键接枝硅源，然后和常见硅源结合。下面是两种方法制备的文献报道，其中第一种的过程有点复杂，不是很明白每一步的作用与意义。第二是EtOH/MTEOS或者是water/precursor的比例都不一样，这个应该怎么调节。麻烦做过相关工作的科研大神指导一下。 1、Typical Procedure for the Preparation of the Sol for Hydrophobic Precursors (MTEOS, VTEOS).MTEOS (100 mL) was hydrolyzed in acidic medium (H2O with HCl , pH 3.8). The hydrolysis molar ratio water/precursor was 20. The mixture was stirred overnight at room temperature and evaporated to the initial volume of the precursor. This solution was placed at 2 °C for 1 week, allowing the decantation of a hydrophobic phase, rich of hydrolyzed and condensed MTEOS. This phase was dissolved in diethyl ether (150 mL) to remove residual water after phase separation. Then, diethyl ether was evaporated and replaced by THF so that the dried solid residue after evaporation of the solvents represents 30% in mass. This prepared sol can be stored at −24 °C and kept for several months. Typical Procedure for the Preparation of a Hybrid Monolith. The chromophore is dissolved in the minimum of THF and added to 1 g of the sol under moderate heating (for example 45 °C) to increase the solubility. The mixture is stirred using an orbital stirrer for 5 min at room temperature and placed in a PTFE mold. APTES (45 μL) is quickly added to the mixture under stirring for 20 s (orbital stirrer) to induce fast condensation of the network at room temperature. The mold is closed. The gel is formed after a few minutes at room temperature. After gelation, the loaded mold is partially opened and put in a drier at 45 °C. The gel is slowly dried for 48 h at 45 °C and for another 24 h at 80 °C. The resulting xerogel glass materials with a doping up to 40% in mass (400 mM concentration) were prepared with chromophores 1 and 2. 2、Preparation of Materials; Typical Procedure for the Preparation of Grafted Hybrids: In procedure (c), the materials were prepared by using MTEOS as starting precursor hydrolyzed in acidic medium (H2O, HCl or AcOH, PH=2.5) in the presence of ethanol (molar ratio EtOH/MTEOS=3). The hydrolysis molar ratio water/precursor was 3. The mixture was stirred overnight and evaporated to the initial volume of precursor. APTES solution in ethanol was added to neutralize the sol. In the second step, the dyes were added to the sol as a solution in THF with the desired concentration. Addition of H2O (pH 2.6) and stirring of the mixture during 7 days was necessary to achieve hydrolysis and condensation of the chromophore with the matrix and prevent precipitation of the dye during the drying step. After aging was finished, the gels were dried between 70 and 110 oC in PTFE moulds. The volume after shrinkage was approximately half of the original volume. |
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4楼2014-08-13 16:32:35
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2楼2014-08-12 20:53:05
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3楼2014-08-12 21:31:47
hujinyang
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5楼2015-02-15 06:01:40
