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"Gregory, Georgina"
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Easy access to oxygenated block polymers via switchable catalysis
Oxygenated block polyols are versatile, potentially bio-based and/or degradable materials widely applied in the manufacture of coatings, resins, polyurethanes and other products. Typical preparations involve multistep syntheses and/or macroinitiator approaches. Here, a straightforward and well-controlled one-pot synthesis of ABA triblocks, namely poly(ether-
b
-ester-
b
-ether), and ABCBA pentablocks, of the form poly(ester-
b
-ether-
b
-ester’-
b
-ether-
b
-ester), using a commercial chromium catalyst system is described. The polymerization catalysis exploits mechanistic switches between anhydride/epoxide ring-opening copolymerization, epoxide ring-opening polymerization and lactone ring-opening polymerization without requiring any external stimuli. Testing a range of anhydrides, epoxides and chain-transfer agents reveals some of the requirements and guidelines for successful catalysis. Following these rules of switch catalysis with multiple monomer additions allows the preparation of multiblock polymers of the form (ABA)
n
up to 15 blocks. Overall, this switchable catalysis delivers polyols in a straightforward and highly controlled manner. As proof of potential for the materials, methods to post-functionalize and/or couple the polyols to make higher polymers are demonstrated.
Multiblock oxygenated polyols often show better properties than the constituent polyols, but their synthesis can be complex and difficult. Here a switchable catalysis concept is described which allows for the efficient preparation of multiblock poly(ether-
b
-ester) materials starting from mixtures of common monomers.
Journal Article
High-performance plastic made from renewable oils is chemically recyclable by design
Plastics are invaluable materials, but they use up petroleum resources and persist in the environment. A high-performance plastic derived from renewable oils has been designed at the molecular level to be truly recyclable.
A bio-based polymer that is readily converted back into its monomer.
Journal Article
Closing the loop on recycling bioplastics
Key targets are to diversify the raw materials used to make plastics beyond fossil fuels; to conserve the embedded energy and valuable resources in their structures; to fully maintain their useful properties through multiple recycling loops; and to design plastics whose molecular structure can be completely disassembled when necessary2-4. The US Environmental Protection Agency found that, in 2018, less than 10% of all plastics, and only about 30% of HDPE bottles, were being recovered from mixed-plastic waste streams and recycled (see go.nature.com/3jw8meq). Encouragingly, however, the reported chemistries seem well suited for use with industrial methods. [...]the reported system seems consistent with European legislation that requires manufacturers to take responsibility for the plastics in their products after consumer use.
Journal Article
2020 roadmap on solid-state batteries
Li-ion batteries have revolutionized the portable electronics industry and empowered the electric vehicle (EV) revolution. Unfortunately, traditional Li-ion chemistry is approaching its physicochemical limit. The demand for higher density (longer range), high power (fast charging), and safer EVs has recently created a resurgence of interest in solid state batteries (SSB). Historically, research has focused on improving the ionic conductivity of solid electrolytes, yet ceramic solids now deliver sufficient ionic conductivity. The barriers lie within the interfaces between the electrolyte and the two electrodes, in the mechanical properties throughout the device, and in processing scalability. In 2017 the Faraday Institution, the UK's independent institute for electrochemical energy storage research, launched the SOLBAT (solid-state lithium metal anode battery) project, aimed at understanding the fundamental science underpinning the problems of SSBs, and recognising that the paucity of such understanding is the major barrier to progress. The purpose of this Roadmap is to present an overview of the fundamental challenges impeding the development of SSBs, the advances in science and technology necessary to understand the underlying science, and the multidisciplinary approach being taken by SOLBAT researchers in facing these challenges. It is our hope that this Roadmap will guide academia, industry, and funding agencies towards the further development of these batteries in the future.
Journal Article
Recyclable Li‐Metal Battery Electrolytes via In Situ Cyclic Carbonate Polymerization
Enabling recycling and improving performance are key challenges for next‐generation electrolytes for rechargeable batteries. Here, an equilibrium polymerization: trimethylene carbonate (TMC) ring‐opening polymerization, in the presence of lithium difluoro(oxalato)borate salt, is utilized to form an electrolyte in situ during coin cell fabrication for lithium batteries. This process creates a semi‐solid poly(trimethylene carbonate) electrolyte with high ambient ionic conductivity (0.52 mS cm−1), thermal stability (Td, 5% = 160 °C), and oxidative stability up to 4.7 V. Using this electrolyte with commercial lithium iron phosphate cathodes, results in 97% capacity retention after 350 cycles at 2C, achieving theoretical capacities of 170 mAh g−1 at 0.1C. The cells retain excellent performance at high current densities (86 mAh g−1 at 4C). Post‐use, the polymer can be separated from the salt and selectively recycled to pure starting monomer (TMC) through a solid‐state chemical recycling process. The recycled monomer, when repolymerized to reform the polycarbonate electrolyte, yields cells with performance identical to the original. The exploitation of polymerization‐depolymerization equilibria offers a useful strategy for enhancing battery performance, ensuring effective material recycling, and advancing a circular economy. A recyclable polycarbonate electrolyte is synthesized in situ in a lithium‐metal battery. Excellent cell performance is obtained owing to its high conductivity and (electro)chemical stability. The electrolyte is recovered after extended battery cycling, chemically recycled back to monomer, and repolymerized, obtaining comparable cell performance. This concept will help develop future recyclable polymer electrolytes and deliver a circular economy for batteries.
Journal Article
Go-go dancing – femininity, individualism and anxiety in the 1960s
Mainly performed by young women at nightclubs and discotheques, go-go dancing was a high-energy, free-form, dance style of the 1960s. Go-go dancers were employed to entertain crowds and to create a ‘cool’ ambience, wearing very revealing outfits including mini dresses, short-fringed skirts, tank tops, tight shorts and calflength boots. The dance style soon reached mainstream media platforms such as the US television show Hullabaloo and ABC’s Shindig, where girls could be seen suspended in clear plastic cages above the dancefloor. Before the Second World War partner dancing was the norm and social dance typically involved close physical contact, often as part of traditional courtship ritual. Moreover, most of the earlier dances required men to take the lead and to physically guide their female partner. A striking characteristic of go-go was the fact that girls usually danced alone, sometimes placed on podiums and often separate from the crowd. In this respect, go-go dancing can be viewed as an extreme extension of a growing trend towards solo dancing. The article explains how go-go dancing could be seen as reflecting social changes occurring during the 1960s, a time when gradual loss of faith in traditional sources of social guidance – religion, government, marriage – saw the rise of greater individualism. Women’s growing emancipation and a move towards selfdirection were embodied by go-go dancers, whose free style movements and rejection of formal steps metaphorically embody the dilemma of a generation of women facing an uncertain future.
Journal Article
Careers in Media and Film
A virtual career coach, this practical handbook offers encouragement, advice, information, and case studies to help students make the most of the opportunities in this very competitive career world. The book can be used as a textual support for careers modules and PDP (Personal Development Planning), graduate workshops, on-line courses and as a departmental or careers library resource. Equally, it works effectively as a self-help guide to enable individuals to focus on their career and life development.
eBook
Cyclic carbonates from sugars and carbon dioxide : synthesis, polymerisation and biomedical applications
The biodegradability and when functionalised biocompatibility of aliphatic polycarbonates (APCs) makes them an attractive class of materials for biomedical applications such as tissue engineering scaffolds and drug-delivery carriers. One route to accessing a wide-range of well-defined and functional APCs is the controlled ring-opening polymerisation (ROP) of cyclic carbonates. In turn, these would ideally be prepared by the direct coupling of CO2 with diols to give water as the only by-product. In this way, the combination of CO2 and sugar-derived diols draws upon two natural renewable building blocks for the construction of polycarbonates that are anticipated to show good biocompatibility properties. Chapter 2 develops a simple and mild alternative to the traditional use of phosgene derivatives for the synthesis of six-membered cyclic carbonates from 1,3-diols and CO2. DFT calculations highlighted the need to lower both the CO2-insertion and ring-closing kinetic barriers to cyclic carbonate formation. Organic superbase, 1,8- diazabicyclo[5.4.0]undec-7-ene (DBU) enabled the formation of carbonate species at 1 atm CO2 pressure whereas, the introduction of a leaving group strategy lowered the cyclisation barrier. Mechanistic considerations suggested a kinetic preference for ring- closing via a nucleophilic addition-elimination pathway rather than a SN2-like intramolecular cyclisation. Chapter 3 applies the procedure with CO2 to the preparation of a novel monomer from natural sugar, ᴅ-mannose. ROP was carried out via an organocatalytic approach and a preference for head-tail linkages in the polycarbonate backbone indicated by NMR spectroscopy and supported by DFT calculations. Chapter 4 utilises CO2 to invert the natural stereochemistry of sugars and create a thymidine-based monomer. The thermodynamic parameters of the ROP with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) catalyst are determined and the properties of the polycarbonates investigated to include preliminary cell attachment studies. Finally, chapter 5 details the synthesis of cyclic carbonates from 2- deoxy-ᴅ-ribose and the investigation into the different ROP behaviour of the α- and β- anomers. The ability to tune the polymer properties through copolymerisation with trimethylene carbonate (TMC) is also discussed.
Dissertation