Polymers with Sugar Buckets - The Attachment of Cyclodextrins onto Polymer Chains

2010 ◽  
Vol 63 (2) ◽  
pp. 195 ◽  
Author(s):  
Firdaus Yhaya ◽  
Andrew M. Gregory ◽  
Martina H. Stenzel
Keyword(s):  
Radical Polymerization ◽  
Liquid Crystalline ◽  
Star Polymers ◽  
Drug Carriers ◽  
Polymer Chains ◽  
Polymer Science ◽  
Molecular Sensors ◽  
Crystalline Polymers ◽  
Reversible Addition ◽  
Cyclodextrin Polymers

This Review summarizes the structures obtained when marrying synthetic polymers of varying architectures with cyclodextrins. Polymers with cyclodextrin pendant groups were obtained by directly polymerizing cyclodextrin-based monomers or by postmodification of reactive polymers with cyclodextrins. Star polymers with cyclodextrin as the core with up to 21 arms were usually obtained by using modified cyclodextrins as initiator or controlling agent. Limited reports are available on the synthesis of star polymers by arm-first techniques, which all employed azide-functionalized cyclodextrin and ‘click’ chemistry to attach seven polymer arms to the cyclodextrin core. Polymer chains with one or two cyclodextrin terminal units were reported as well as star polymers carrying a cyclodextrin molecule at the end of each arm. Cyclodextrin polymers were obtained using different polymerization techniques ranging from atom transfer radical polymerization, reversible addition–fragmentation chain transfer polymerization, nitroxide-mediated polymerization, free radical polymerization to (ionic) ring-opening polymerization, and polycondensation. Cyclodextrin polymers touch all areas of polymer science from gene delivery, self-assembled structures, drug carriers, molecular sensors, hydrogels, and liquid crystalline polymers. This Review attempts to focus on the range of work conducted with polymers and cyclodextrins and highlights some of the key areas where these macromolecules have been applied.

scholarly journals Initiation of RAFT Polymerization: Electrochemically Initiated RAFT Polymerization in Emulsion (Emulsion eRAFT), and Direct PhotoRAFT Polymerization of Liquid Crystalline Monomers

2021 ◽  
Vol 74 (1) ◽  
pp. 56 ◽  
Author(s):  
Caroline Bray ◽  
Guoxin Li ◽  
Almar Postma ◽  
Lisa T. Strover ◽  
Jade Wang ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Colloidal Stability ◽  
Molar Mass ◽  
Raft Polymerization ◽  
Monomer Conversion ◽  
Continuous Phase ◽  
Side Chain ◽  
Crystalline Polymers ◽  
Reversible Addition ◽  
Polymerization Conditions

We report on two important advances in radical polymerization with reversible addition–fragmentation chain transfer (RAFT polymerization). (1) Electrochemically initiated emulsion RAFT (eRAFT) polymerization provides rapid polymerization of styrene at ambient temperature. The electrolytes and mediators required for eRAFT are located in the aqueous continuous phase separate from the low-molar-mass-dispersity macroRAFT agent mediator and product in the dispersed phase. Use of a poly(N,N-dimethylacrylamide)-block-poly(butyl acrylate) amphiphilic macroRAFT agent composition means that no added surfactant is required for colloidal stability. (2) Direct photoinitiated (visible light) RAFT polymerization provides an effective route to high-purity, low-molar-mass-dispersity, side chain liquid-crystalline polymers (specifically, poly(4-biphenyl acrylate)) at high monomer conversion. Photoinitiation gives a product free from low-molar-mass initiator-derived by-products and with minimal termination. The process is compared with thermal dialkyldiazene initiation in various solvents. Numerical simulation was found to be an important tool in discriminating between the processes and in selecting optimal polymerization conditions.

Liquid Crystalline Polymers

MRS Bulletin ◽  
1987 ◽  
Vol 12 (8) ◽  
pp. 18-21 ◽  
Author(s):  
Alan Windle
Keyword(s):  
Long Range ◽  
Liquid Crystalline ◽  
Molecular Design ◽  
Orientational Order ◽  
Polymer Melt ◽  
Liquid Crystalline Polymers ◽  
Downstream Processing ◽  
Major Theme ◽  
Polymer Science ◽  
Crystalline Polymers

Not much more than a decade ago, the plastics industry viewed itself as a mature branch of the heavy chemical industry. Its raison d'être was the mass production of four or five main-line polymers, and profits were equated to tonnage output, plant efficiency, and clever downstream processing such as film blowing. The chemistry was essentially simple and the monomer, of course, cheap. There was, however, a spark of new thinking. A trend was developing toward the design and manufacture of more complex, more expensive polymers, with special properties which could command a special price. Such products would sell advanced scientific know-how, not just engineering expertise which could all too easily be exported to the major oil producers in the form of a polymer plant.Designing particular molecules to achieve desired properties is now a major theme of polymer producers. There is a move toward increasing the aromatic content of polymer backbones to achieve greater levels of chemical and thermal stability, while the development of new cross-linking systems remains as chemically intensive as ever. It is, however, the introduction of liquid crystalline polymers which, above all, has exploited the principles of molecular design, while at the same time challenging our understanding in a new area of polymer science.A polymer is “liquid crystalline” where the chains are sufficiently rigid to remain mutually aligned in the liquid phase although the perfect positional periodicity of a crystal is no longer present. In other words there is a long-range orientational order without long-range positional order (Figure 1). Structurally, therefore, the phase is intermediate between a crystal and a liquid leading to the use of the term mesophase. Where the liquid crystalline phase forms on melting the polymer, it is known as thermotropic, but where it is achieved by solvent addition it is called Inotropic. Increasing temperature, or solvent concentration, will eventually lead to the reversion of the liquid crystal phase to the normal isotropic polymer melt.

scholarly journals Living Radical Polymerization by the RAFT Process

2005 ◽  
Vol 58 (6) ◽  
pp. 379 ◽  
Author(s):  
Graeme Moad ◽  
Ezio Rizzardo ◽  
San H. Thang
Keyword(s):  
Radical Polymerization ◽  
Polymer Brushes ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Star Polymers ◽  
Living Radical Polymerization ◽  
Factors Influencing ◽  
Reversible Addition ◽  
Complex Architectures

This paper presents a review of living radical polymerization achieved with thiocarbonylthio compounds [ZC(=S)SR] by a mechanism of reversible addition–fragmentation chain transfer (RAFT). Since we first introduced the technique in 1998, the number of papers and patents on the RAFT process has increased exponentially as the technique has proved to be one of the most versatile for the provision of polymers of well defined architecture. The factors influencing the effectiveness of RAFT agents and outcome of RAFT polymerization are detailed. With this insight, guidelines are presented on how to conduct RAFT and choose RAFT agents to achieve particular structures. A survey is provided of the current scope and applications of the RAFT process in the synthesis of well defined homo-, gradient, diblock, triblock, and star polymers, as well as more complex architectures including microgels and polymer brushes.

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