The controlled radical polymerisation of hydrophobic and cationic monomers via Cu(0)-RDRP

Cu(0)-RDRP can utilise significantly lower catalyst loadings than conventional ATRP methodologies, yielding high conversions and low dispersities. This technique has a simple set-up with reactions typically carried out in glass vials and deoxygenation simply via a short period of nitrogen bubbling. The synthesis of polyacrylates and polyacrylamides has resulted in many successes with a wide scope of materials previously prepared, but the polymerisation of low kp monomers, for example methacrylates and styrene has resulted in significant challenges. Polymerisation conditions that are successful for one monomer or monomer class typically fail for others, so there is no means of knowing the optimal conditions for carrying out a particular polymerisation. Therefore the selection of appropriate conditions for successful polymerisation can be a time consuming and arduous task for both “experts” and non-experts. In chapter 2 of this thesis, one set of conditions are optimised to yield well-defined polyacrylate, polymethacrylate and polystyrene homo and block copolymers. There are very limited reports of the polymerisation of styrene via Cu(0)-RDRP, so further optimisation of this synthesis is provided in Chapter 3, yielding higher molecular weights while maintaining both a high initiator efficiency and a narrow dispersity. A further notable area of challenge within the polymer community is the controlled polymerisation of cationic monomers with reported protocols observing many side reactions and termination events. PDMAEA has many ideal properties making it a good candidate for RNA interference, so this polymer has many potential applications. Chapter 4 illustrates the optimisation of the synthesis of linear and star polymers of DMAEA and the ability of these materials to bind and subsequently release dsRNA in both aqueous solution and in soil is subsequently investigated in chapter 5. This is part of an industrial project funded by Syngenta

A comparison of OSPFv3 and EIGRPv6 in a small IPv6 enterprise network

As the Internet slowly transitions towards IPv6, the routing protocols that are used to forward traffic across this global network must adapt to support this gradual transition. Two of the most frequently discussed interior dynamic routing protocols today are the IETF’s OSPF and Cisco’s EIGRP routing protocol. A wealth of papers have compared OSPF and EIGRP in terms of converge times and resource usage, however few papers have assessed the performance of each when implementing their respective security mechanisms. Therefore a comparison of OSPFv3 and EIGRPv6 will be conducted using dedicated Cisco hardware. This paper will firstly introduce each protocol and its security mechanisms, before conducting a comparison of OSPFv3 and EIGRPv6 using Cisco equipment. After discussing the simulation results, a conclusion will be drawn to reveal the findings of this paper and which protocol performs the best upon implementing their respective security mechanisms within a small IPv6 enterprise network

Parsimonious and efficient assessment of health-related quality of life in osteoarthritis research: validation of the Assessment of Quality of Life (AQoL) instrument

BACKGROUND: The Assessment of Quality of Life (AQoL) utility instrument was psychometrically developed for the general population. This study aimed to explore its potential as an osteoarthritis (OA) outcome measure. METHODS: WOMAC, Lequesne index, SF-36, Visual analogue scales and the AQoL were administered to 222 people with OA. The ability of each questionnaire to detect differences between groups was based on (i) self-rated health (SRH) and, (ii) differences between people on an orthopedic waiting list (WL) vs people with OA in the community (C). Comparisons included effect size, relative efficiency and receiver operator characteristic curves. RESULTS: All instruments detected differences between groups; however no one instrument exhibited superior efficiency. The AQoL demonstrated strong psychometric properties. CONCLUSION: The AQoL has equivalent performance to comparator questionnaires commonly used in OA research and would be a useful adjunct to well-established disease specific scales. The AQoL has important advantages; brevity (12 items), facilitates comparisons between disease groups, and delivers a utility score that can be used in health economic evaluations

Aqueous copper(II) photoinduced polymerization of acrylates : low copper concentration and the importance of sodium halide salts

Photoinduced metal mediated radical polymerization is a rapidly developing technique which allows for the synthesis of macromolecules with defined molecular weight and narrow molecular weight distributions, although typically exhibiting significant limitations in aqueous media. Herein we demonstrate that the presence of alkali metal halide salts in conjunction with low copper concentration and UV irradiation, allows for the controlled polymerization of water soluble acrylates in aqueous media, yielding narrow molecular weight distributions and high conversions. Despite the aqueous environment which typically compromises polymer end group fidelity, chain extensions have also been successfully performed and different degrees of polymerization were targeted. Importantly, no conversion was observed in the absence of UV light and the polymerization could be switched “on” and “off” upon demand as demonstrated by intermittent light and dark periods and thus allowing access to spatiotemporal control

Copper mediated reversible deactivation radical polymerization in aqueous media

Key advances within the past 10 years have transformed copper mediated radical polymerization from a technique which was not very tolerant to protic media into a range of closely related processes capable of control over the polymerization of a wide range of monomers in pure water at ppm catalyst loadings; yielding water soluble macromolecules of desired molecular weight, architecture and chemical functionality, with applications ranging from drug delivery to oil field recovery. In this review we highlight and critically evaluate the synthetic methods that have been developed to control radical polymerization in water using copper complexes, identify future areas of interest and challenges still to be overcome

Copper mediated polymerization without external deoxygenation or oxygen scavengers

Overcoming the challenge of rigorous deoxygenation in copper mediated controlled radical polymerization processes (e.g. ATRP), we report a simple Cu(0)‐RDRP system in the absence of external additives (e.g. reducing agents, enzymes etc.). By simply adjusting the headspace of the reaction vessel, a wide range of monomers, namely acrylates, methacrylates, acrylamides and styrene, can be polymerized in a controlled manner yielding polymers with low dispersities, near‐quantitative conversions and high end group fidelity. Significantly, this approach is scalable (~ 125 g), tolerant to elevated temperatures, compatible with both organic and aqueous media and does not rely on external stimuli which may limit the monomer pool. The robustness and versatility of this methodology is further demonstrated by the applicability to a number of other copper mediated techniques including conventional ATRP and light‐mediated approaches

Cu(0)-RDRP of methacrylates in DMSO: importance of the initiator

The controlled radical polymerization of methacrylates via Cu(0)-mediated RDRP is challenging in comparison to acrylates with most reports illustrating higher dispersities, lower monomer conversions and poorer end group fidelity relative to the acrylic analogues. Herein, we present the successful synthesis of poly(methyl methacrylate) (PMMA) in DMSO by judicious selection of optimal reaction conditions. The effect of the initiator, ligand and temperature on the rate and control of the polymerization is investigated and discussed. Under carefully optimized conditions enhanced control over the molecular weight distributions is obtained furnishing methacrylic polymers with dispersities as low as 1.10, even at very high conversions. A range of methacrylates were found to be tolerant to the optimized polymerization conditions including hydrophobic, hydrophilic and functional methacrylates including methyl and benzyl methacrylate, ethylene glycol methyl ether methacrylate and glycidyl methacrylate. The control retained during the polymerization is further highlighted by in situ chain extensions yielding well-defined block polymethacrylates

Well-defined PDMAEA stars via Cu(0)-mediated reversible deactivation radical polymerisation

The Cu(0)-mediated reversible deactivation radical polymerisation of N,N’-dimethylaminoethyl acrylate in DMSO and IPA at ambient temperature using Cu(0) wire is investigated. Tetra-functional and octa-functional initiators were utilised to facilitate the synthesis of well-defined PDMAEA star homo and block copolymers with a range of molecular weights (Mn ~ 5000-41000 g mol-1). Both solvents demonstrated to be excellent media for the controlled polymerisation of DMAEA yielding narrow molecular weight distributions (Ð ~ 1.1) when the reactions were ceased at ~ 40% conversion. Interestingly, at high conversions (typically > 55%) high and low molecular weight shoulders were evident by SEC when DMSO and IPA were used respectively, suggesting large extent of termination and/or side reactions at prolonged reaction times. Nevertheless, high end group fidelity could be maintained when immediate precipitation of the polymers (at lower conversion) was performed yielding low dispersed P(DMAEA-b-MA) star block copolymers (Ð < 1.19, Mn ~ 20000 g mol-1). Importantly, guidelines on how to prevent hydrolysis, termination and side reactions of PDMAEA as well as how to purify and store such materials are also provided and discussed

A User\u27s Guide to the Encyclopedia of DNA Elements (ENCODE)

The mission of the Encyclopedia of DNA Elements (ENCODE) Project is to enable the scientific and medical communities to interpret the human genome sequence and apply it to understand human biology and improve health. The ENCODE Consortium is integrating multiple technologies and approaches in a collective effort to discover and define the functional elements encoded in the human genome, including genes, transcripts, and transcriptional regulatory regions, together with their attendant chromatin states and DNA methylation patterns. In the process, standards to ensure high-quality data have been implemented, and novel algorithms have been developed to facilitate analysis. Data and derived results are made available through a freely accessible database. Here we provide an overview of the project and the resources it is generating and illustrate the application of ENCODE data to interpret the human genome