Tailoring cementitious materials with genetically, engineered microbial exopolysaccharides, a biologically inspired approach towards high-performance construction materials
Final Report Abstract
In this project, the influence of the mannuronic / guluronic acid ratio and level of acetylation of five different alginates on the properties of their intercalation compounds prepared from Zn(NO3)2 / Al(NO3)3 was investigated. It was found that all types of alginates can successfully intercalate into a Zn2Al-LDH host structure. An increasing content of guluronic acid leads to a larger d-spacing due to the higher steric volume of guluronic acid. Hence, alginates possessing different contents of guluronic acid can be used to modify the interlayer distance in LDHs. Additionally, partial acetylation of the carboxylic groups present in alginate also increases the d-spacing of the LDHs. No chemical interaction of the alginate with Al3+ present in the LDH host structure was detected, but electrostatic interaction between the positively charged inorganic LDH main layer and the negatively charged carboxylic groups of the alginate was proven. SEM investigations confirmed the formation of flexible alginate-LDH nanofoils. In mortar, the flexible nanofoils of such biopolymer-LDH can play a role as nano-reinforcement and consequently improve the brittleness of mortar by increasing the tensile strength. Thus, the concept of modifying the purely inorganic microstructure of hardened cement with an organic-inorganic composite material was successfully proven.
Publications
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“Intercalation of the Microbial Biopolymers Welan Gum and EPSI into Layered Double Hydroxides”, Zeitschrift für Naturforschung B 67b (2012) 479-487
Plank J., Ng S., Foraita S.
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“Effect of biotechnologically modified alginates on LDH structures", Bioinspired, Biomimetic and Nanobiomaterials 4 (2015) 174-186
de Reese J., Sperl N., Schmid J., Sieber V., Plank J.
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“Impact of biotechnologically modified alginates on the d-spacing of LDH structures", 18th International Symposium on Intercalation Compounds (ISIC18), Strasbourg (France), May 31 – June 4, 2015, Compilation of Abstracts p. 61
de Reese J., Sperl N., Storcheva O., Schmid J., Sieber V., Plank J.
