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Title: Study of polymer composites containing nano- and micro-particles for materials engineering applications
Author: Fiaz, Ahssad
ISNI:       0000 0004 7970 2274
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2018
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The research conducted in this report is broad; however, it demonstrates innovative approaches for several potential applications. The projects advocate the use of composite scaffolds to enhance or improve the roles of standard polymer-based materials. Two techniques have been utilised to create the structures, poly-high internal phase emulsions, templated using two immiscible liquids, and the continuous phase containing the monomer material. Also, hydrogel synthesis, a hydrophilic monomer cured to form a highly swellable polymeric gel. The three subject areas are polymeric hydrogels - as potential sensors; microcarriers for bone and tissue engineering, and poly-high internal phase emulsions (poly-HIPEs) as thermal insulators; all three are briefly outlined below in chronological order of their chapter allocation: The production of polymeric sensors is the application considered in the following chapter using the environmentally sensitive polymer - poly-isopropyl acrylamide. Initially started using the poly-HIPE route, but the attention was focused on hydrogels as a more suitable alternative. Due to the improved mechanical nature and ability to retain structural integrity in water, the properties were enhanced using magnetically responsive nano- and micro-particles. The project utilises ferrogels are hydrogels loaded with magnetite that were synthesised via a co-precipitation and solvothermal route, creating particle sizes of 1 - 10 nm and around 250 nm, respectively. Additionally, the use of Maxwell-inductance Bridge demonstrates a low, but detectable response for in-situ samples. Although results for the Microparticle containing gels are unclear, they possess significant volume transition responses compared to in situ ferrogels; and with some modification of the inductance bridge, there is potential for the transition of micro-ferrogels to be detectable with the chosen sensing method. Microcarriers are highly porous materials that provide a surface suitable for cellular adhesion. In this case, emulsion templating was utilised to create porous beads with embedded carbonyl-iron particles to provide a magnetic response. By applying an external magnetic field, a novel method is used to create fluid shear stress in order to encourage osteogenic differentiation. Common osteo-indicators such as alkaline phosphatase activity, collagen and calcium were used as a measure for an osteogenic response. In the last section, a case for Poly-HIPEs as thermal insulation materials is proposed. Due to their controllable nature, they have characteristics similar to those found in insulation materials, small pores, a highly porous and hydrophobic structure are key factors in quality insulators. Porosity was controlled by increasing the volume of water, which formed the internal phase; samples with 60% to 90% were manufactured. The conductivity of the material was similar to conventional insulators; however, they were less insulating with increasing porosity. Addition of wood fibre improved the insulation properties of the 90% porous sample but had the opposite effect on the sample with low porosity.
Supervisor: Claeyssens, F. C. ; Allwood, D. A. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available