分别以高分子三嵌段共聚物P123(PEO20-PPO70-PEO20)和F127(PEO106-PPO70-PEO106)为模板剂,通过高温水热法制备了具有超低介电常数的规则介孔氧化硅材料(OMSs).当合成温度达到200℃时,得到的产物仍可保持规则的介孔结构.X射线衍射和氮气吸附结果表明,OMSs系列材料具有规则的二维六方或体心立方介孔结构、大的比表面积和孔容及均一的孔径分布.29Si MAS NMR分析表明,OMSs与低温(100℃)合成产物相比具有更高的骨架缩合度,从而具有优异的水热稳定性.由于具有大的孔容和高的骨架缩合度,OMSs表现出了超低的介电常数.以P123为模板剂,200℃下合成的OMS的介电常数可达1.31.OMSs作为一类稳定的超低介电常数材料,对于绝缘材料的发展具有潜在的应用价值.
Conventional quantum dots inherently carry the risk of cytotoxicity. Considering the biomedical limitations, an amino acid and vitamin were utilized to prepare highly luminescent carbon dots. Ascorbic acid and lysine were used to synthesize water soluble carbon dots which are highly hiocompatible as both reactants and essential nutrients.
Co-salen functionalized on graphene with an average pore size of 27.7 nm as a heterogeneous catalyst exhibited good catalytic activity and recyclability in cyclohexene oxidation.
