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Investigating polymers as precursors for the synthesis of covalent and dynamic (nano)materials for sensing applications
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Efstathiou, Spyridon (2022) Investigating polymers as precursors for the synthesis of covalent and dynamic (nano)materials for sensing applications. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3909752
Abstract
The main objective of this thesis was to investigate potential polymeric materials for use in the development of a hydrogel sensor capable of distinguishing the different types of sweat glands on human skin.
In Chapter 2, the synthesis and characterization of semi-IPN poly(ethylene glycol) (PEG) hydrogels (PEG700-DA/PEGx, x = Mn) is described. The developed hydrogels were intended as sensor matrices for the colorimetric detection of sweat urea secreted from eccrine glands targeting indirect visualization. The detection of urea was achieved through the urease/phenol red assay where a colorimetric change occurred due to the pH changes. Materials were synthesized via photo-induced free radical polymerization while both pristine and sensor gel formulations were characterized by a variety of techniques including rheology, mechanical testing, and thermal characterization. The naked-eye detection of urea from model sweat mixtures was successful while a smart-phone based RGB quantification approach is also proposed.
In Chapter 3, an attempt to replace the previously formulated covalent hydrogels with dynamic imine-based gels was explored with the potential to avoid radical-processes and introduce self healing properties. The synthesis of a multi-benzaldehyde crosslinker is described through a two-step process using aqueous Cu-RDRP and the Steglich esterification to modify with benzaldehyde. The crosslinker formed imine-based hydrogels after reaction with the amines of glycol chitosan (GC) while demonstrating slow self-healing. Materials were characterized by rheology and mechanical testing, demonstrating soft properties thus a comparison with lower functionality crosslinkers is also presented. Finally, the effect of reinforcing with reduced graphene oxide (rGO) is exhibited yielding stiffer and tougher hydrogels with higher self-healing efficiencies compared to the pristine gels as analyzed by rheology.
Finally, Chapter 4 deals with the synthesis of homopolymers and amphiphilic block copolymers of 2-(acetoacetoxy)ethyl methacrylate (AEMA) monomer via photoinduced Cu(II)-mediated RDRP. Well-defined homopolymers and amphiphilic block copolymers with PEG were characterized and subsequently modified with primary amines through dynamic enaminone bonds. The modification efficiencies along with thermal analysis were studied. The self-assembly of the amphiphilic blocks in water through the direct hydration approach is also described together with the pH-sensitive properties of the formed nanoparticles
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QD Chemistry Q Science > QP Physiology T Technology > TP Chemical technology |
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Library of Congress Subject Headings (LCSH): | Colloids, Sweat glands, Chemical detectors, Urea, Addition polymerization, Block copolymers, Amphiphiles, Self-assembly (Chemistry) | ||||
Official Date: | September 2022 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Chemistry | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Haddleton, David M. | ||||
Format of File: | |||||
Extent: | xxxiv, 239 pages : colour illustrations, colour charts | ||||
Language: | eng |
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