Influence of oxidation degree on the physicochemical properties of oxidized inulin

Franklin Afinjuomo, Paris Fouladian, Thomas G. Barclay, Yunmei Song, Nikolai Petrovsky, Sanjay Garg

    Research output: Contribution to journalArticlepeer-review

    Abstract

    This paper reports the oxidation of inulin using varying ratios of sodium periodate and the characterization of the inulin polyaldehyde. The physicochemical properties of the inulin polyaldehyde (oxidized inulin) were characterized using different techniques including 1D NMR spectroscopy, 13C Nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetric (DSC), ultraviolet-visible spectroscopy (UV), and scanning electron microscopy (SEM). The aldehyde peak was not very visible in the FTIR, because the aldehyde functional group exists in a masked form (hemiacetal). The thermal stability of the oxidized inulin decreased with the increasing oxidation degree. The smooth spherical shape of raw inulin was destructed due to the oxidation, as confirmed by the SEM result. The 1HNMR results show some new peaks from 4.8 to 5.0 as well as around 5.63 ppm. However, no aldehyde peak was found around 9.7 ppm. This can be attributed to the hemiacetal. The reaction of oxidized inulin with tert-butyl carbazate produced a carbazone conjugate. There was clear evidence of decreased peak intensity for the proton belonging to the hemiacetal group. This clearly shows that not all of the hemiacetal group can be reverted by carbazate. In conclusion, this work provides vital information as regards changes in the physicochemical properties of the oxidized inulin, which has direct implications when considering the further utilization of this biomaterial.

    Original languageEnglish
    Article number1025
    Number of pages18
    JournalPolymers
    Volume12
    Issue number5
    DOIs
    Publication statusPublished - 1 May 2020

    Bibliographical note

    This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)

    Keywords

    • Aldehyde content
    • Degree of oxidation and physicochemical properties
    • Oxidized inulin
    • Periodate oxidation

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