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Title: Syntheses and characterization of novel layered double hydroxide structures and the development of LDH/Polymer nanocomposites
Author: Hu, Gang
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2007
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Abstract:
The syntheses of layered double hydroxides (LDHs) with novel structures, and the development of LDHlPolymer nanocomposites, are the focus of the work described in this thesis. A general introduction to the synthetic methods, structural properties, and established application~ of LDH materials is given in Chapter 1. The emerging application of LDH in polymer-based nanocomposites, some present obstacles in LDH/polymer nanocomposites R&D, and the possible solutions are also discussed. LDH materials are conventionally prepared using a co-precipitation method. Chapter 2 reports a very facile method to prepare LDH films with highly-oriented crystal arrangements. In Chapter 3, a waterlbi-alcohol system is used to prepare nitrate Mg2AI-LDH' nanoparticles with various size distributions. LDH particles prepared by this method are hydrophilic. The separate aqueous compartments are believed to act as nanoreactors which confine the growth and aggregation of LDH particles during the syntheses. Attempts to control the LDH particle size distributions by adjusting the alcohol contents are also described inthis chapter. In order to cater to the demands from different applications, hydrophobic LDH particles with highly exfoliated structures have also been prepared using a waterlNaDDS/isooctane reverse microemulsion system, which have been described in Chapter 4. The reverse microemulsion method makes it possible to prepare LDH particles with monolayer structures by changing the [water]/[surfactant] ratios. In a further study described in Chapter 5, some LDH superstructures with unique morphologies, are described. By the addition of a copolymer surfactant to the original waterlNaDDS/isooctane system, oriented growth of the LDH particles can be triggered because of the so-called polar media percolation effect. The detailed mechanism for the formation of these superstructures is also proposed. In Chapter 6, a study of the preparation of LDR/polymer nanocomposites is reported. All the nanocomposites were prepared by the in situ polymerization method. The results show that LDH fillers prepared by reverse microemulsions bring remarkable improvements to the thermal and mechanical properties for nanocomposites than the conventional co-precipitation/intercalation method since the former ones can be more unifonnly dispersed in the polymer matrices. An overall conclusion of the project has been drawn in Chapter 7. Also listed in this chapter are some possible aspects ofthe future work. The experimental procedures and characterising techniques employed in this work are listed in Chapter 8.
Supervisor: Not available Sponsor: Not available
Qualification Name: University of Oxford, 2007 Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.487258  DOI: Not available
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