Facile Preparation of Nanofibrillar Networks of "Ureido-Chitin" Containing Ureido and Amine as Chelating Functional Groups

Kathirvel Ganesan; Markus Heyer; Lorenz Ratke; Barbara Milow

doi:10.1002/chem.201804405

Facile Preparation of Nanofibrillar Networks of "Ureido-Chitin" Containing Ureido and Amine as Chelating Functional Groups

Chemistry. 2018 Dec 20;24(72):19332-19340. doi: 10.1002/chem.201804405. Epub 2018 Nov 20.

Authors

Kathirvel Ganesan¹, Markus Heyer¹, Lorenz Ratke¹, Barbara Milow¹

Affiliation

¹ Aerogels and Aerogel Composites, Institute of Materials Research, German Aerospace Center, Linder Hoehe, 51147, Cologne, Germany.

PMID: 30325076
DOI: 10.1002/chem.201804405

Abstract

Aerogels of polysaccharides with chelating functions can be useful as supports in many applications because of their hosting properties. This work demonstrates a facile method for the preparation of aerogels of chitosan derivative "ureido-chitin", containing ureido functional groups. The nanofibrillar networks of "ureido-chitin" were produced by the nucleophilic addition of amine groups of chitosan with isocyanic acid prepared in situ. The presence of ureido functional groups was confirmed by FTIR, solid-state CP-MAS ¹³ C and ¹⁵ N NMR analyses. No crosslinking of molecular chains was observed. The maximum degree of ureido functional groups was estimated to be about 66 %. Characterization by powder XRD confirmed that the polymer chains self-assembled, with the chitin polymers oriented in a highly ordered crystalline structure. The nanofibrillar networks showed no solubility under either aqueous acidic or alkaline conditions. Bio-based hosting materials of this kind with two different hosting functional groups, ureido and amine, can potentially be utilized for a wide range of applications in aqueous medium, including filters, catalysis and biomedicine.

Keywords: aerogels; biomass; chitin; chitosan; gels.