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Title: High porosity macroporous polymer beads as delivery vehicles for crush release
Author: Cegla, Dan
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2013
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The work reported in this thesis was part of the larger EPSRC (Engineering and Physical Sciences Research Council) and dstl (Defence Science and Technology Laboratory) funded project called CRASHCOMPS with the main aim to establish approaches for crack arrest and self healing in composites. The aim of this subproject was to produce macroporous polymer beads with either open pore or closed-cell structures, which can be utilised as delivery vehicles for crush-release of self-healing agents but which could ultimately also be used for crush-release of other active ingredients, such as dyes, drugs, enzyme, acids etc. The work reported in this thesis describes the synthesis and characterisation of novel micrometre sized macroporous polymer beads which can be easily handled and dispersed in liquids, gels, epoxy resins and particle blends and are therefore potentially useful for a large variety of applications. Throughout this thesis, macroporous poly(methyl methacrylate-co-ethylene glycol dimethacrylate) beads were synthesised via double emulsion templating in combination with suspension and microfluidic polymerisation techniques as it allowed the synthesis of macroporous polymer beads with predefined pore structures and bead sizes, respectively. By using different internal phase volume ratios and surfactants of different concentration for stabilisation of the primary emulsions, macroporous polymer beads with different open pore morphologies and mechanical properties could be synthesised. Furthermore by using particles as emulsifiers for the primary emulsion templates, macroporous beads with closed-cell structures and significant improvement in the mechanical properties of resulting beads could be realised, which are important for crush-release applications. This work led to the formation of novel high internal phase emulsions (HIPEs), which use active ingredients, such as hydrochloric acid or guar gum degrading enzymes, as internal emulsion phase and which allowed to produce in situ filled macroporous polymer beads. These beads then allowed the release of the active ingredients upon crushing. Subsequently, the ambitious aim to use macroporous beads as carriers for self-healing agents was approached and synthesised macroporous beads were post filled with epoxy resin and sealed afterwards. In addition, macroporous beads filled with epoxy resin were incorporated into composite matrices and their effect on the overall mechanical properties as well as the amount of unreacted resin available for self-healing approaches after curing of the composite investigated and determined, respectively. Eventually novel hydrophilic macroporous polymer monoliths based on [2-(acryloyloxy)ethyl] trimethylammonium chloride and 2-(methacryloyloxy)ethyl trimethylammonium chloride with N,N?-methylenebis(acrylamide) as crosslinker were produced and characterised for potential in situ encapsulation with epoxy resin.
Supervisor: Bismarck, Alexander ; Steinke, Joachim Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available