Structural differences of the soluble oligomers and insoluble polymers from acid-catalyzed conversion of sugars with varied structures
2019
Xu, Qing | Hu, Xun | Shao, Yuewen | Sun, Kai | Jia, Peng | Zhang, Lijun | Liu, Qing | Wang, Yi | Hu, Song | Xiang, Jun
In this paper, acid-catalyzed conversion of nine sugars (xylose, glucose, fructose, galactose, sucrose, maltose, lactose, raffinose, and β-cyclodextrin) with different sizes, steric structures and functionalities were investigated and impacts of the varied sugars on structures of resulting polymers were focused. Under similar reaction conditions, the yields of the carbon materials (insoluble polymers) formed followed the order: xylose » lactose > galactose > β-cyclodextrin > maltose > sucrose > fructose > glucose > raffinose. Increasing temperature enhanced transformation of soluble oligomers into insoluble ones. Morphologies of the carbon materials were closely related to sugar structures. Diameters of carbon materials (microsphere form) obtained from the disaccharides and oligosaccharides were larger than that of monosaccharides. Furthermore, the microspheres from oligosaccharides had a higher affinity to each other, resulting from continued polymerization as some reactive functionalities were retained in carbon materials. In addition, graphite structure was formed in the carbon materials, even at 160 °C.
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