Suspension, yielding, microstructure and applications of bacterial cellulose dispersion

Soft matter materials have been widely explored and applied because of their unique rheological response. One of the most common approaches to fluid microstructure design is to create a colloidal gel, a self-supported network that forms spontaneously from attractive particles. Fluid products containing colloidal gels have superior suspension abilities, because they possess a yield stress that makes the fluid elastic until a threshold stress is exceeded. Yield stress fluids have been widely studied, but the local aspects of yielding, and the effects of particle shape on suspension performance are still not well-understood. This work examines the unique yielding of bacterial cellulose fiber networks using a new microrheology technique developed specifically for this purpose. The fiber gels exhibit a dynamic structural rearrangement response to applied stress that is shown to be advantageous in applications like particle suspension and surface coating. The cellulose system and its unique structural and yielding properties are also studied in several systems with direct relevance to commercial formulated material production. A suspension of dense particles trapped within a cellulose fiber network is characterised as it slowly compresses and fails under its particulate load, and the phenomenon is used to measure gel permeability and model the long-time behaviour of such systems in order to predict stability. Medical nasal sprays incorporating cellulose microfibrils are shown to be greatly enhanced in their ability to coat and adhere to surfaces, as the gel yield stress provides a more consistent flow resistance than traditional viscosity modification. Finally, a novel form of microcapsule is developed by engineering the growth of bacterial cellulose on emulsion droplet interfaces, creating soft, permeable shells with custom geometries. The structures are proposed as a new approach for encapsulation and protection, and potentially a framework for artificial cells.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2019

Author dc:creator

• Song, Jie

• Bacterial cellulose
• Yield stress
• Microstructure

Statement dc:rights

• open access
• CC BY-NC-ND 3.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by-nc-nd/3.0/au/

Language dc:language

EN

Identifier

https://doi.org/10.26190/unsworks/21782

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/65820