The objective of this work was to synthesise potential polymeric materials to use in agricultural applications, particularly as pesticide carriers. Synthesis of solid microcapsules, which contain hydrophobic pesticides, from functional polymers, was the primary goal. In addition, promising materials such as poly(dimethylsiloxane) (PDMS) and acid-labile containing polymers were also explored. The extraordinary reactivity of isocyanates towards nucleophiles offers an interesting synthetic tool as a catalyst-free reaction. Unfortunately, the high reactivity of isocyanate during the polymerisation process is a major concern, thus a facile approach in order to synthesise stable functional polymer was first investigated. Chapter 2 details the synthesis of two types of isocyanate side chain containing copolymers, poly(methyl methacrylate-co-isocyanatoethyl methacrylate) (P(MMAm-co-IEMn)) and poly(benzyl methacrylate-co-isocyanatoethyl methacrylate) P(BnMAm-co-IEMn), via Cu(0)-mediated controlled radical polymerisation. Both copolymers were functionalised with dibutylamine, octylamine, and (R)-(+)-α-methylbenzylamine, which further proved the successful incorporation of the isocyanate groups. Subsequently, P(BnMAm-co-IEMn) was used for the fabrication of liquid core microcapsules via an oil-in-water interfacial polymerisation with diethylenetriamine as a crosslinker. Furthermore, chapter 3 illustrates the synthetic route of solid microcapsules containing hydrophobic pesticides; this illustrates the incorporation of biodegradable materials, modern controlled radical polymerisation techniques and isocyanate chemistry. An α, ω-poly (ɛ-caprolactone) SET-LRP initiator is first prepared by esterification to obtain a degradable halide initiator. Subsequently, biodegradable P(BnMAn-co-IEMn) was polymerised via the conditions from chapter 2. An isocyanate-containing copolymer was used to fabricate a microcapsule which consists of imidacloprid (IMI), followed by water removal via spray dryer. Chapter 4 details an efficient tool to synthesise an amphiphilic copolymer containing PDMS. The versatility of hydrosilylation has been exploited for the preparation of an ABA block copolymer of PDMS and poly(ethylene glycol) methacrylate (PEGMA), which can be potentially used to prepare polymeric micelles. Also, to demonstrate the adaptability of this method, different methacrylates and vinyl terminated methacrylic macromonomers were applied to modified hydride terminated PDMS. Finally, the α, ω-hydroxyl terminated poly(acetal) SET-LRP initiator was synthesised from the condensation and esterification reaction. A favourable Cu(0)-mediated controlled radical polymerisation and degradation under an acidic conditions of acetal initiator was affirmed. Thus, this offers a great opportunity of using this initiator to synthesise isocyanate-containing copolymers, certainly, an acid-labile microcapsule to use as an agrochemical carrier is potentially achievable.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:731418 |
| Date | January 2017 |
| Creators | Risangud, Nuttapol |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/96908/ |
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