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This paper reviews recent developments in RAFT Polymerization with proton switchable RAFT agents. We report on the successful use of N-methyl- N-(4-pyridinyl) dithiocarbamates RAFT agents for controlling the polymerization of N, N-dimethylacrylamide (DMAm) in aqueous media, the dependence of the RAFT agent activity on acid type and acid strength (for best results a stoichiometric amount of a strong acid should be used), and the synthesis of block copolymers such as poly(DMAm)-block-poly( N-vinylpyrrolidone). We describe a new class of switchable RAFT agents, the N-aryl- N-(4-pyridinyl) dithiocarbamates. These RAFT agents are more active with more activated monomers (MAMs) in protonated (switched) form and more active with less activated monomers (LAMS) in non-protonated (unswitched) form. Finally we examine the dependence of RAFT polymerization of N-vinylcarbazole (NVC) on the type of RAFT agent used (dithiobenzoate, trithiocarbonate, xanthate, switchable dithiocarbamate). Contrary to popular belief, NVC does not behave as a typical LAM, its polymerization is best controlled with a trithiocarbonate RAFT agent, and NVC should be described as an intermediate activity monomer (IAM). [ABSTRACT FROM AUTHOR]

Reversible addition-fragmentation chain transfer (RAFT) is one of the most robust and versatile methods for controlling radical . With appropriate selection of the RAFT agent for the monomers and reaction conditions, it is applicable to the majority of monomers subject to radical . The process can be used in the synthesis of well-defined homo-, gradient, diblock, triblock, and star polymers and more complex architectures, which include microgels and . In this Focus Review we describe how the development of RAFT and RAFT application has been facilitated by the adoption of continuous flow techniques using and through the use of high-throughput methodology. Applications described include the use of RAFT in the preparation of polymers for optoelectronics, therapeutics, and star polymer rheology . [ABSTRACT FROM AUTHOR]

Abstract: This review traces the development of addition–fragmentation chain transfer agents and related ring-opening monomers highlighting recent innovation in these areas. The major part of this review deals with reagents that give reversible addition–fragmentation chain transfer (RAFT). These reagents include dithioesters, trithiocarbonates, dithiocarbamates and xanthates. The RAFT process is a versatile method for conferring living characteristics on radical polymerizations providing unprecedented control over molecular weight, molecular weight distribution, composition and architecture. It is suitable for most monomers polymerizable by radical polymerization and is robust under a wide range of reaction conditions. It provides a route to functional polymers, cyclopolymers, gradient copolymers, block polymers and star polymers. [Copyright &y& Elsevier]

A new diepoxide monomer (ADTDE) containing an allylicdithioethermoiety has been synthesized to extend the suite of monomers that formnetworks exhibiting radical-mediated photoplasticity. These cross-linkedpolymers show permanent shape change under load and stress relax onlywhen under the stimulus of visible or UV radiation. The Lewis base-catalyzedreaction of the epoxide groups in ADTDE with tri- and tetrafunctionalthiols was monitored by differential scanning calorimetry and infraredspectroscopy. These curing systems were found to be more efficientthan anionic, cationic, or anhydride polymerizations. The dynamicmechanical thermal analysis of ADTDE with the tetrathiol showed thatthe network was rubbery at room temperature which is considered idealfor the demonstration of photoplasticity. The photoinduced creep behaviorwas shown to be controlled by the presence of active free radicalsin the matrixon cessation of irradiation, the creep was terminated.The stress relaxation of the stretched network specimens during UVirradiation was studied and was found to be similar to that shownpreviously for thiol–vinyl ether networks. As expected, thecross-link density of networks prepared from ADTDE with the trithiolwas lower than that formed with the tetrathiol and this was foundto have a significant influence on the rate and extent of photoplasticityobservedthe less highly cross-linked ADTDE/trithiol systemexhibited more rapid and more extensive photoplasticity since it containedfewer network strands. [ABSTRACT FROM AUTHOR]

Novel symmetrical (alkane-a,v-diyl)(bis[3,3' -allyl dithioethers]) compounds and their ether analogues, have been synthesised from (alkane-Α,ω-diyl)bis([2-{chloromethyl}allyl]sulfane) precursors, for use in crosslinked polymers which exhibit photoplastic behaviour. Facile synthesis and purification of these monomers was achieved if the alkane-Α,ω-diyl moiety had at least one oxygen atom in this linker. The number of sulfur atoms in these monomers was varied from four to two to zero to produce monomers which can be used to evaluate their importance on the photoplasticity behaviour. [ABSTRACT FROM AUTHOR]

The structures of the “Z” and “R”substituentsof a RAFT agent (Z–C(S)S–R) determine a RAFT agent’sability to control radical polymerization. In this paper we reportnew acid/base switchable N-aryl-N-pyridyl dithiocarbamates (R = −CH2CN, Z = −N(Py)(Ar))which vary in substituent at the 4-position of the aryl ring and theuse of these to control molecular weight and dispersity. In theirprotonated form, the new RAFT agents are more effective in controllingpolymerization of the more activated monomer, methyl acrylate (MA),whereas in their neutral form they provide more effective controlof the polymerization of less activated monomers, N-vinyl carbazole (NVC) and vinyl acetate (VAc). For each polymerization,the apparent chain transfer coefficient (Ctrapp) shows a good correlation with Hammett parameters.Dithiocarbamates with more electron-withdrawing aryl ring substituentshave the higher Ctrapp. Thisdemonstrates the influence of polar effects on Ctrappand supports the hypothesis that the activityof these RAFT agents is determined by the availability of the lonepair of the dithiocarbamate nitrogen. [ABSTRACT FROM AUTHOR]

The article provides information regarding the study on radical polymerization. Researchers define the reversible addition - fragmentation chain transfer (RAFT) polymerization as a versatile process in conferring living characteristics and at the same time as a reversible deactivation polymerization. It notes that the RAFT process can control the polymerization of most monomers polymerized by radical polymerization. Details of related to the study of RAFT agents for polymerization are presented.