Gel Development Using Cellulose Nanocrystals

Abbasi Moud, Aref

Gel Development Using Cellulose Nanocrystals

dc.contributor.advisor	Hejazi, Hossein
dc.contributor.advisor	Sanatinezhad, Amir
dc.contributor.author	Abbasi Moud, Aref
dc.contributor.committeemember	Wadood, Hamad Y.
dc.contributor.committeemember	Federico, Salvatore
dc.contributor.committeemember	Wong, Joanna
dc.contributor.committeemember	Mahinpey, Nader
dc.date	2020-11
dc.date.accessioned	2021-01-04T21:37:13Z
dc.date.available	2021-01-04T21:37:13Z
dc.date.issued	2020-06-18 0:00
dc.description.abstract	Cellulose Nano Crystal (CNC) are naturally derived nanoparticles with a slender shape that own a remarkably high aspect ratio. Due to its mechanical properties with Young modulus in the range of 120-160 GPa and proven biocompatibility, CNC is an attractive nanoparticle for many applications. In the acid-based method of CNC production, the particles develop naturally negative charges, inducing an electrostatic repulsion between CNC particles and, consequently, when suspended in the water, a stable suspension. Upon introducing a coagulant, such as NaCl above a threshold value in the CNC suspension, phase separation happens where the system evolves toward gelation. The individual CNC particles, through aggregation, contribute to building a 3D gel fractal structure. Where a porous self-similar 3D structure spans in space, the design and synthesis of CNC-based gels are tunable and flexible. Mechanical properties of the hydrogels can also be tuned when CNC is coupled with polymers such as Polyvinyl alcohol (PVA). Herein, the CNC-based gelation process is monitored, and the formed gels are characterized. The zeta potential and Dynamic Light Scattering are employed to measure the hydrodynamic radii and the surface charges of particles in different CNC-coagulant loadings. The gel morphology and CNC cluster fractal dimensions are recorded using Scanning Election Microscopy (SEM) and Transmission Electron Microscopy (TEM). The CNC-based gel behavior under large amplitude strains is also characterized by non-linear rheology. The gel collapse behavior and the self-healing dynamics of CNC-based gels are also quantified using fluorescence recovery after photobleaching (FRAP) analysis. It is shown that CNCs can coagulate upon increasing the ionic strength of the medium, where the mechanical stability of the CNC-based gels (i.e., storage modulus), is an increasing function of NaCl and CNC concentration. Non-linearity of the gel was shown to be more influenced by NaCl concentration. The addition of PVA makes the CNC hydrogels mechanically robust, where two jumps in values of storage modulus as a function of frequency is observed. The jumps are attributed to the network formation between CNCs and CNC-polymer. Finally, the FRAP analysis using Confocal Laser Scanning Microscopy reveals that the CNC mobility in gel media is influenced by both CNC and NaCl concentration. The result of this study can be used in controlling CNC hydrogels properties, such as the gel self-healing and mechanical properties, and in assembling a 3-D hydrogel structure with CNC. In practice, the developed CNC-based hydrogels can be used in tissue engineering.
dc.identifier.doi	http://dx.doi.org/10.11575/PRISM/38503
dc.identifier.uri	http://hdl.handle.net/1880/112911
dc.language.iso	en	en
dc.publisher.faculty	Graduate Studies	en
dc.publisher.faculty	Schulich School of Engineering
dc.publisher.institution	University of Calgary	en
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.	en
dc.subject	Colloidal Science
dc.subject	Cellulose Nano Crystals (CNC)
dc.subject	Polymer
dc.subject	Confocal laser microscopy (CLSM)
dc.subject	Large-Amplitude Oscillatory Shear (LAOS)
dc.subject	Microstructure Characterization
dc.subject	Hydrogels
dc.subject	Complex Fluids
dc.subject	Soft matter
dc.subject	Interfaces
dc.subject.classification	Engineering--Materials Science
dc.subject.classification	Engineering--Chemical
dc.subject.classification	Engineering--Biomedical
dc.subject.classification	Chemistry--Polymer
dc.title	Gel Development Using Cellulose Nanocrystals
dc.type	doctoral thesis
thesis.degree.discipline	Engineering – Chemical & Petroleum
thesis.degree.grantor	University of Calgary	en
thesis.degree.name	Doctor of Philosophy (PhD)