| dc.description.abstract | This thesis provides, through a collection of publications, an analysis of existing materials and/or constructs in an endeavor to examine what anomalous mechanical properties can be brought out and studied from these existing materials and/or constructs, or evolutions of them. The known and developed structures were studied through a combination of mathematical models, molecular computational techniques, namely forcefield simulations and density functional theory (DFT) simulations, and finite elemental analysis simulations. The results achieved through these techniques allowed for in-depth analyses of the materials and constructs, and their mechanisms of operation were successfully identified and considered in terms of underlying actions. This approach allowed for a novel understanding of such anomalous mechanical properties, and how they may be tailored to requirements and therefore possibly applied.
Poly(phenylacetylene) networks were reconsidered, and novel networks made from penta- and tetra- substituted poly(phenylacetylene) sheets were discovered. These networks were studied for mechanical properties, including anomalous properties, and were found to buckle when loaded in off-axis directions. This buckling property, which is normally seen as an undesirable property, was analysed, and considered for its advantages and engineerability within the field of auxetics. Furthermore, the pores these networks exhibit due to the nature of the substitutions were discussed in terms of possible nanodelivery and nanofiltration applications.
Honeycombs, including re-entrant, standard, and hybrid configurations were studied to understand the effect of the component materials on the properties of the systems. It was found that through configuring the thermal expansion properties of the comprising ligaments, one could produce systems with positive, zero, and negative thermal expansion. This allows for greatly increased tailorability and possible applicability of such systems.
The anomalous properties of boron arsenate (BAsO4) with 𝐼4̅ symmetry were considered, being a material known to exhibit a negative Poisson’s ratio and negative linear compressibility under certain conditions. Also, this crystal had not yet been studied in detail in order to thoroughly understand and quantify the underlying actions which present these properties. These underlying actions could allow for future designs and applications to better Formatted: HighlightFormatted: Highlight
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apply the properties discovered in this remarkable crystal. Work was also carried out on an equivalent macroscale model which was studied through finite element analysis (FEA) and mathematical modelling in order to generalise the model into a structure which is not effected by the chemistry of the atoms within the crystal, but is instead made of materials at macroscale. | en_GB |
