Fabrication of polymer-derived ceramics with hierarchical porosities by freeze casting assisted by thiol-ene click chemistry and HF etching
Fabrication of polymer-derived ceramics with hierarchical porosities by freeze casting assisted by thiol-ene click chemistry and HF etching
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DOI：
10.1016/j.jeurceramsoc.2019.09.038
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发表时间：
2020-02
影响因子：
5.7
通讯作者：
Xifan Wang;Franziska Schmidt;A. Gurlo
中科院分区：
文献类型：
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作者：
Xifan Wang;Franziska Schmidt;A. Gurlo
采用冷冻浇铸技术结合低温硫醇-烯光聚合成功地制备了具有高度定向孔隙率的大孔聚合物衍生碳氧化硅。它表明，自由基引发的硫醇烯点击反应有效地交联的含乙烯基的液体聚硅氧烷成不熔的热固性材料，即使在低温下。此外，通过添加二氧化硅纳米粉末，采用基于混合溶液和悬浮液的冷冻铸造。结果表明，纳米SiO2的存在并不限制光致交联的完全进行，但对SiOC/SiO2泡沫材料的光致交联性能影响不大。热解后的HF酸处理产生的SiOC整料产生分级孔隙率，与蚀刻后的SiOC/SiO2纳米复合材料表现出最高的比表面积为494 m2/g和孔径横跨宏观，介孔和微孔范围。新开发的方法提供了一个通用的解决方案，用于制造具有可控孔隙率的块状聚合物衍生陶瓷。
The freeze casting technique assisted with cryo thiol-ene photopolymerization is successfully employed for the fabrication of macroporous polymer-derived silicon oxycarbide with highly aligned porosity. It is demonstrated that the free radical initiated thiol-ene click reaction effectively cross-linked the vinyl-containing liquid polysiloxanes into infusible thermosets even at low temperatures. Furthermore, mixed solution- and suspension-based freeze casting is employed by adding silica nanopowders. SiOC/SiO2foams with almost perfect cylindrical shapes are obtained, demonstrating that the presence of nano-SiO2does not restrict the complete photoinduced cross-linking. The post-pyrolysis HF acid treatments of produced SiOC monoliths yields hierarchical porosities, with SiOC/SiO2nanocomposites after etching demonstrating the highest specific surface area of 494 m2/g and pore sizes across the macro-, meso- and micropores ranges. The newly developed approach gives a versatile solution for the fabrication of bulk polymer-derived ceramics with controlled porosity.