ORALS

SESSION: RecyclingMonPM2-R5	Kolomaznik International Symposium (8th Intl. Symp. on Sustainable Materials Recycling Processes & Products)
Mon. 28 Nov. 2022 / Room: Arcadia 2
Session Chairs: Carmen Gaidau; Session Monitor: TBA

17:10: [RecyclingMonPM212] OS
Ordered Structures Formation in Multicomponent Polysaccharide Systems; Effect of Graphene Oxide
Ivan Kelnar¹ ; Alexander Zhigunov² ; Jiří Dybal² ; ¹, Prague, Czech Republic; ²Institute of Macromolecular Chemistry, Czech Academy of Sciences, Prague, Czech Republic;
Paper Id: 161 [Abstract]

Numerous studies indicate fair ability of water soluble polysaccharides including their blends and nanocomposites to form organized structures in solutions and gels [1]. E. g., fibrillar structure and network formation was found in aqueous solutions and gels of methylcellulose (MC) while even thermo-reversible fibrillation of MC/cellulose nanocrystal-based hydrogels was found [2]. Surprisingly, formation of these structures in rigid polysaccharides (mostly films) and their impact on mechanical performance were reported less frequently. The presented study deals with an unknown unexpected effect of 2-hydroxyethylcellulose (HEC) on structure and mechanical performance of methylcellulose (MC) films. This leads to synergistic as well as antagonistic effects [3] on mechanical performance in dependence on modifiers content and ratio. The values of modulus of MC containing 5 and 10 % HEC exceed those of the linear model, which indicates synergistic effect consisting in formation of ordered structures. At the same time, higher content of HEC leads to worse properties indicating dominant contribution of its lower parameters. In spite of absence of direct insight into the structure, combination of XRD, polarized light microscopy and rheology indicates a high effect of small content of HEC on formation of favorable ordered structures and a slight hindering effect of GO on this process. Rheological evaluation indicates ability of HEC to support formation of ordered structures in MC also in water-solution. Important result is that unlike high reinforcing effect of low graphene oxide (GO) content on single MC and HEC components, its presence in blends decreases mechanical properties as a result of disturbing of HEC-induced structural transformations. Further unexpected feature is that negative effects of higher HEC content on mechanical performance are enlarged by GO. The results confirm complex effect of blending and GO on structure and properties of the MC/HEC system.

References:
1. Dogsa, I., Cerar, J., Jamnik, A.,& Tomšič, M. (2017). Supramolecular structure of methyl cellulose and lambda- and kappa-carrageenan in water: SAXS study using the string-of-beads model. Carbohydrate Polymers, 172, 184–196.
2. Hynninen, V., Hietala, S., McKee, J. R., Murtomäki, L., Rojas, O. J., Ikkala, O., Nonappa. (2018). Inverse Thermoreversible Mechanical Stiffening and Birefringence in a Methylcellulose/Cellulose Nanocrystal Hydrogel. Biomacromolecules, 19, 2795–2804.
3. Kelnar, I., Zhigunov, A., Kaprálková,L., Krejčíková, S., Dybal, J. (2020) Synergistic effects in Methylcellulose/ Hydroxyethylcellulose blend: Influence of components ratio and graphene oxide Carbohydrate Polymers 236, Art. Nr. 116077