Waterborne Polyurethane Nanocomposites with Rigid Nanofillers of Fungal Origin

Silvia Mares Barbosa
Lecture of the lecture cycle
19.9.2024 10:30, Lecture room A

Novel robust polycarbonate-polyurethane (PC-PUR) nanocomposite elastomers were synthesized, via waterborne PC-PUR dispersions (WPUD) and aqueous suspensions of chitin-glucan nanocrystals (ChGNC) as precursors. The incorporation of the high-aspect-ratio fibrous ChGNC into the polycarbonate-PUR markedly improved its stiffness (increase in modulus by 1 order), already at 1wt.% of ChGNC, without significantly reducing its excellent extensibility. The WPUD matrix precursor offers a high production safety, minimized health- and pollution risks (eliminating volatile organic compounds), easy manipulation, possible dilution of the precursor with water, as well as compatibility with aqueous additives. In this way, the water-suspended hydrophilic ChGNC nanofiller easily was dispersed in the WPUD. This nanofiller was obtained from natural mycellium (Aspergillus Niger) via a biocompatible method – the defibrillation by treatment with a natural-compound-based deep-eutectic solvent mixture (DES). The disintegration of the chitin bundles into ChGNCs yielded a 1D nanofiller with a very high aspect ratio, which proved to be a very efficient reinforcement in PUR. ChGNC is a derivative of chitin, which is the main structural material of fungal cell walls and crustacean shells. ChGNC itself is attractive because of very strong hydrogen bonding, but it also possesses additional highly desirable properties like biocompatibility, biodegradability, anti-inflammatory- and antimicrobial properties, in which it surpasses crustacean chitin. The characterization of the nanocomposites included their morphology (filler dispersion studied via electron microscopy and X-ray scattering), dynamic-mechanical thermal analysis, micro-tensile-, relaxation-, and creep tests. The study used nature-sourced or biocompatible raw materials, and bio-compatible intermediates and solvents, in order to ensure that the final products could meet the strict standards for future applications in tissue engineering and biomedical applications.

The lecture is presented in English