Formation of mesophase microbeads from bulk mesophase pitch induced by fullerene

富勒烯诱导体型中间相沥青形成中间相炭微球

A transformation of naphthalene-based coalescenced mesophase pitch(NMP)to mesophase microbeads was achieved by heating a mixture of NMP and fullerene(C_(60)).This is different from the conventional process of the liquid-phase carbonization of isotropic pitch to the emergence of carbon microbeads in the matrix and finally their growth to form a 100%anisotropic bulk meso-phase,but rather a reverse transformation.The effects of C_(60) loading and reaction temperature on the morphological transformation of mesophase were investigated by polarizing optical and scanning electron microscopies.The physical changes in the NMP induced by C_(60) were characterized by thermogravimetric analysis,Fourier transform infrared spectroscopy,X-ray diffractometry and Raman spectroscopy.The results show that the coalesced NMP can be converted to a spherical type at 300-320℃ with the addition of 5%C_(60),and the size of the mesophase microbeads increases with increasing temperature.Furthermore,a model is established to ex-plain the unique induction effect of C_(60) in the transformation process.This work makes the morphological transformation of MP con-trollable,and provides a new idea for the understanding and research of mesophase pitch.

中间相沥青(Mesophase pitch,MP)形态的可控转变对于研究MP的形成机理和应用具有重要的现实意义。本研究将富勒烯(fullerene,C_(60))添加于萘基中间相沥青(Naphthalene-based mesophase pitch,NMP)中,并进行热处理,实现了中间相显微形态从融并体型到球状的转变。通过偏光显微镜和扫描电子显微镜研究了C_(60)添加量和热处理温度对中间相形态转变的影响。热重分析、傅立叶变换红外光谱、X射线衍射和拉曼光谱对C_(60)诱导NMP成球这一物理过程进行了印证。结果表明,在300~320℃的热处理温度下,添加5%的C_(60)可以使融并体型中间相转化为球形液晶态MP,中间相小球的尺寸随温度升高而增大。此外,建立了一个模型来解释C_(60)在转变过程中的独特π电子诱导效应。本工作揭示了C_(60)诱导下的中间相的形态转变行为,为后续中间相形态的调控及应用研究提供了新思路。