催化剂对乳液模板法制备碳材料形貌的影响

以液体石蜡为油相,间苯二酚和甲醛的水溶液为水相,吐温80和司班80为乳化剂,获得油/水(O/W)型乳状液.将该乳状液聚合、碳化去除模板后制得了碳材料,研究了不同催化剂对所得碳材料形貌的影响.结果表明:选择NaOH为催化剂时,制得的碳材料是一种具有孔壁和孔洞的多孔碳泡沫,典型样品的孔径约为1-2μm;当氨水为催化剂时,所得碳材料是由微球或者相互缠绕的蠕虫状粒子组成的块体材料,这些微球或粒子的直径主要集中在1-2μm,与NaOH为催化剂时所得碳泡沫的孔径尺寸相当.研究发现,氨水的加入使得乳液体系发生了相转化,由原来的O/W型乳液逐渐转变为W/O型高内相乳液.从分子间氢键出发,应用内聚能理论探讨了催化剂导致的乳液相变以及不同形貌碳材料的形成过程.

Effect of Catalysts on the Morphologies of Carbon Materials Synthesized by an Emulsion Templating Method

An oil in water (O/W) emulsion with a resorcinol and formaldehyde (R+F) water solution as the external phase and liquid paraffin as the internal phase together with Span 80/Tween 80 as emulsifiers was obtained. Carbon materials were prepared by polymerization of the emulsion, followed by carbonization for template removal. The effect of catalysts on the morphologies of the carbon materials was investigated. The results indicate that the resultant representative carbons area type of porous carbon foam and possess pore walls and pores of 1-2 μm in size when NaOH is used as a catalyst. However, monolithic carbon materials consisting of microspheres or intertwinded wormlike particles were prepared using ammonia as an alternative catalyst. The diameters of these microspheres or particles were mainly around 1-2 μm and these dimensions are similar to the pore sizes of the carbon foams. We find that ammonia causes the initial O/W emulsion system to experience a phase inversion towarda W/O high internal phase emulsion.A mechanism involving intermolecular H-bond interactions and cohesive energy theory is proposed to explain the catalyst-induced phase inversion phenomenon as well as the formation of carbon materials with different morphologies.