【作者】 肖作毅；

【导师】 王安杰； 金东杓；

【作者基本信息】 大连理工大学 ， 工业催化， 2010， 博士

【摘要】 有序大孔材料广泛地应用于催化剂载体,分离吸附和光子晶体等方面。此外,三维有序多孔阵列在微反应器中的应用是最近研究的热点。本论文以聚二甲基硅烷模具(PDMSmold)中组装的聚苯乙烯微球胶体晶体结构作为硬模板,采用不同软刻蚀技术成功制备了三维有序大孔阵列。又将排列在PDMS mold中的二氧化硅微球转移到硅片上,制备了结构上新颖和稳定的多层二氧化硅微球组装的微结构。采用离心方法将聚苯乙烯微球排列在PDMS mold通道中,又在离心力作用下将陶瓷前驱体溶液填充在胶体晶体模板间隙,经过低温固化和高温焙烧,制备了三维有序大孔SiCN陶瓷阵列。通过高分辨率扫描电镜和光学显微镜的表征,证明了采用此方法,能够在相对较短的时间内制备出高质量三维有序大孔SiCN陶瓷阵列。此外,又考察了在110℃热处理不同时间对模板中聚苯乙烯微球形貌的影响,瓶颈尺寸在300nm至820nm范围内。以上不同的微球模板出发,制备出了不同“窗口”尺寸的三维有序大孔SiCN陶瓷,窗口尺寸从258 nm增加到720nm,而比表面积从477 m2g-1降低至337 m2g-1。采用了离心方法制备了高质量的三维有序多孔SiCN材料,但是依然存在难以制备出大面积的三维有序大孔阵列的问题。因此,采用了直接挥发组装法在PDMS mold通道中组装聚苯乙烯微球,利用转移微模塑技术(microtransfer molding,μTM)制备出不同尺寸的三维有序大孔全氟聚醚阵列(perfluoropolyether, FP) (50μm-400μm)。实验结果证明采用此方法,不仅大大缩短了操作流程所需时间,而且增大了三维有序大孔阵列的面积。此外,使用不同图案的PDMS mold,制备了不同形状的三维有序大孔全氟聚醚阵列。大面积的三维有序多孔阵列的成功制备降低了随后光刻蚀技术制备有三维有序大孔阵列的SU-8-50微通道的难度。采用了不同组装方法在PDMS mold通道中组装二氧化硅微球,然后制备二氧化硅微球组装的阵列。实验表明采用毛细管模塑方法不能制备出高质量和稳定的阵列,而利用转移微模塑技术和层层叠加方法制备了结构新颖和稳定的一层、二层和三层的二氧化硅微球组装的阵列。通过对二氧化硅微球不同温度焙烧后进行表征,证明了随着温度的提高,二氧化硅微球阵列在硅片上越来越稳定。当焙烧温度为950℃时,在硅片上得到了稳定的二氧化硅微球阵列。扫描电镜和显微镜照片表明此结构具有几十微米的大孔和几百或几十纳米的小孔。另外,这种稳定的二氧化硅微球阵列可以使用光刻蚀技术放入到SU-8-50微通道中,和二氧化硅微球组装的胶体晶体结构相比,孔隙率从0.63降到0.26,二层二氧化硅微球阵列所产生的床层阻力降低了63倍。此结构作为微混合器用于微反应器中流体的混合,大大提高了液体的混合效率。和无微结构的微通道相比,混合效率提高了近4倍。更多还原

【Abstract】 3D ordered porous materials can usually be used as catalysts, separation columns and photocrystals.3D ordered porous patterns have attracted much attention due to application in the microfluidic area. In this thesis, different kinds of 3D ordered porous patterns were fabricated from PS spheres packed template in the PDMS mold. A novel and robust 3D multilayered silica beads-packed microstructure was successfully prepared by transferring the silica beads-packed patterns in the PDMS mold onto surface of silicon wafers.PS spheres were organized into the PDMS mold under the centrifugal force. The 3D ordered macroporous SiCN material was obtained by curing the precursor at low temperature and thermally decomposing the PS spheres at high temperature. The obtained structure was characterized by SEM and optical microscopy. The results shows high-quality 3D ordered macroporous SiCN material could be achieved in a short time using a centrifugal method. During the process we also studied the morphologies of PS spheres after annealing for different periods. The size of necks formed by heating could be controlled in the range of 300 nm to 820 nm. The window sizes of the resulting 3D macroporous SiCN ceramic among the interconnected macropores increased from 258 nm to 740 nm, and the BET surface area was reduced from initial 443 m2 g-1to 337 m2.Even through high-quality 3D ordered porous SiCN material with the tailed window sizes was obtained, it is difficult to achieve the material over a large area on a substrate. PS spheres were organized into the PDMS mold using a directed evaporation-induced self-assembly method. Subsequently, through a microtransfer molding technique, the 3D ordered macroporous perfluoropolyether (FP) patterns with various dimensions were fabricated over a large area on a silicon wafer in relatively short time. Different kinds of porous patterns can be also fabricated using PDMS mold with varying patterns. More importantly, the 3D macroporous FP patterns over a large area were easily built inside a SU-8-50 microchannnel using a photolithography method.Finally, a 3D silica bead-packed microstruture was fabricated by transferring the packed silica spheres inside the PDMS onto the substrate using different soft lithographic technique. It was found that the single-layered silica bead-packed patterns with a high quality could not be achieved using the MIMIC method reported previously. A novel and robust 3D silica bead-packed microstrutures in a single、double and triple layers were fabricated using a microtransfer molding technique combined with a layer-by-layer technique. The stability of silica bead-packed patterns was improved by heating at high temperature. A stable monolithic structure with mechanical integrity was obtained on a silica wafer when heating the silica bead-packed patterns at 950℃. The double-layered silica bead-packed patterns had a bimodal pore distribution in micron and sub-micron range. Moreover, the microstructure was easily embedded inside the SU-8-50 microchannel with the aid of photolithography. Compared with densely packed silica spheres in the channel, the pressure drop was decreased by a factor of 63 when the void fraction of the packed bed in the channel increased from 0.26 to 0.63. The two-layered 3D silica beads-packed microstructure was used as a micro-mixer to enhance the mixing performance of solvents. Utilization of the system results in a fourfold increase in the mixing efficiency in the microchannel.更多还原