Evaluation of a novel, Scanning Electron Microscope based surface chemical mapping technique for characterising polymeric biomaterials

This thesis presents the evaluation of a novel Scanning Electron Microscope based biomaterial characterisation technique which possess the ability to provide chemical surface mapping of polymer-derived biomaterials. The ability of a biomaterial to sustain cellular life is a critical dependency for successful deployment of polymer based biomaterials and consequently the cellular/biomaterial surface interface is a key focus for research. Chemical, structural and topographic characteristics at nanometre and micrometre length scales have been shown to be key factors in the promotion of cellular attachment. For biomaterial characterisation only a small number of existing characterisation techniques provide the capability to undertake surface analysis at the nanoscale. Of these none provide the ability to undertake multiscale (including nanoscale) chemically mapping of beam sensitive biomaterials. Therefore, a requirement clearly exists for a high resolution, multiscale, chemical mapping capability for characterisation of synthetic polymer derived biomaterials.

This thesis evaluates the recently developed technique of Secondary Electron Hyperspectral Imaging (SEHI). SEHI captures and configures spectral information from material samples presented within a Scanning Electron Microscope to enable image analysis that reveals and maps chemical bonding within polymer derived biomaterials to surface depths of <10 nm. Although it has been shown that the SEHI technique can provide extensive chemical and synchronised structural characterisation information, three key questions remain over its future use for the characterisation of polymer derived biomaterials. 1) Can SEHI deliver insights into the mechanical properties of a material? 2) Is the captured SE spectra able to identify specific functional groups that play a key role in biomaterials engineering /TE? And if so can SEHI map these functional groups at the nanoscale? 3) Does the surface roughness of different polymer systems impact on SEHI`s ability to allow for chemical mapping? This thesis will focus on providing evidence to determine the answers to these questions. The conclusion of my analysis presented in this thesis makes a persuasive argument for researchers to consider establishing SEHI as the toolset of choice for polymer characterisation in the context of establishing chemically mapping of the surface of biomaterials due to its effectiveness, flexibility and unique insights.