- Dispersion polymerisation in supercritical CO2 using macro-RAFT agents
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Fluorinated macro-RAFT agents can act as in situ stabilisers while exhibiting good control over block copolymers formed by dispersion polymerisation in supercritical CO2 to yield well-defined spherical particles with a fluorinated "halo". The Royal Society of Chemistry.
- Zong, Mengmeng,Thurecht, Kristofer J.,Howdle, Steven M.
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- Reversible addition-fragmentation chain transfer polymerization: End group modification for functionalized polymers and chain transfer agent recovery
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A simple reaction which leads to the full removal of thiocarbonyl, the thio end group from the polymeric chains, and the recovery of the chain transfer agent was discussed. Methyl methacrylate was mixed with S- methoxycarbonylphenylmethyl dithiobenzoate (
- Perrier, Sebastien,Takolpuckdee, Pittaya,Mars, Craig A.
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- Design, synthesis, and phase behaviors of a novel triphenylene-based side chain liquid crystalline diblock copolymer
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A novel double Tp-based liquid crystalline (LC) diblock copolymer (PMTS-b-PMT6S) composed of poly[3,6,7,10,11-pentakis (hexyloxy)-2-oxytriphenylene] (PMTS) and poly{6-[3,6,7,10,11-pentakis(hexyloxy)-2-oxytriphenylene]} (PMT6S) was designed and successfully synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. While PMTS is a rigid columnar-shaped (ΦN) polymer, PMT6S is a stable hexagonal columnar phase (ΦH) polymer. The phase behaviors of diblock copolymers were studied by DSC, POM and 1D WAXD. The results showed that the weight fraction of PMT6S (fPMT6S) has a significant effect on the LC phase behaviors and phase structures of diblock copolymers. Both glass transition temperature and phase transition temperature of the diblock copolymers from LC phase to isotropic phase reduced with the weight fraction of PMT6S in the feed. When the fPMT6S ≤ 58.1%, PMTS-b-PMT6S-1 to PMTS-b-PMT6S-3 show similar properties to PMTS, which formed a stable columnar nematic phase (ΦN), while when the fPMT6S ≥ 64.2%, PMTS-b-PMT6S-4 and PMTS-b-PMT6S-5 show similar properties to PMT6S, which presented a hexagonal symmetry columnar phase (ΦH). Comparison between the diblock copolymer and homopolymer (PMTS and PMT6S) indicates that the content of the spacer was crucial to determine the LC structures. Through the study one can better understand the interrelation of microstructures and Tp DLC orders, which constitutes the key basis for various applications.
- Ban, Jianfeng,Pan, Lulu,Shi, Bo,Zhang, Hailiang
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- A new practical synthesis of tertiary S-alkyl dithiocarbonates and related derivatives
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Decomposing a tertiary diazo derivative in the presence of a dithionodisulfide gives the corresponding tertiary thionosulfide (xanthate, dithiocarbamate, or dithioester) in good yield.
- Bouhadir, Ghenwa,Legrand, Nicolas,Quiclet-Sire, Beatrice,Zard, Samir Z.
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- A novel synthesis of functional dithioesters, dithiocarbamates, xanthates and trithiocarbonates
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A novel synthesis of functional dithioesters, dithiocarbamates, xanthates and trithiocarbonates is described. Heating a bis(thiocarbonyl) disulfide with an azo-compound results in the formation of (thiocarbonyl)sulfanyl derivatives in moderate to high yield. The process is proposed as the method of choice for preparing tertiary (thiocarbonyl)sulfanyl compounds and is compatible with a wide range of functionalities (e.g. carboxy, hydroxy and nitrile).
- Thang, San H.,Chong, Bill Y.K.,Mayadunne, Roshan T.A.,Moad, Graeme,Rizzardo, Ezio
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- Microarray glass slides coated with block copolymer brushes obtained by reversible addition chain-transfer polymerization
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The reversible addition-fragmentation chain-transfer polymerization was used to prepare microarray slides grafted with polymer brushes for DNA-based applications. Block copolymer brushes of N,N-dimethylacrylamide (DMA) and glycidyl methacrylate (GMA), poly(DMA-b-GMA) were prepared by extending living poly(dimethylacrylamide) chains. The functional surface was used as a substrate for oligonucleotide hybridization experiments. The results were compared to those provided by glass slides coated by a self-assembled monolayer made of (3-glycidyloxypropyl)trimethoxysilane. Surfaces coated with block polymer brushes bearing oxirane groups are more efficient as substrates for oligonucleotide hybridization than surfaces coated with nonpolymeric self-assembled monolayers containing the same functional group. The high probe grafting density and hybridization efficiency achieved with this polymeric coating reveal the importance of the block architecture to ensure good accessibility of the immobilized probe. The new surface was characterized by static angle measurements and diffuse reflectance FT-IR spectroscopy on a silica model system.
- Pirri, Giovanna,Chiari, Marcella,Damin, Francesco,Meo, Alessandra
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Read Online
- Fluorescent and Water Dispersible Single-Chain Nanoparticles: Core–Shell Structured Compartmentation
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Single-chain nanoparticles (SCNPs) are highly versatile structures resembling proteins, able to function as catalysts or biomedical delivery systems. Based on their synthesis by single-chain collapse into nanoparticular systems, their internal structure is complex, resulting in nanosized domains preformed during the crosslinking process. In this study we present proof of such nanocompartments within SCNPs via a combination of electron paramagnetic resonance (EPR) and fluorescence spectroscopy. A novel strategy to encapsulate labels within these water dispersible SCNPs with hydrodynamic radii of ≈5 nm is presented, based on amphiphilic polymers with additional covalently bound labels, attached via the copper catalyzed azide/alkyne “click” reaction (CuAAC). A detailed profile of the interior of the SCNPs and the labels’ microenvironment was obtained via electron paramagnetic resonance (EPR) experiments, followed by an assessment of their photophysical properties.
- Hoffmann, Justus F.,Roos, Andreas H.,Schmitt, Franz-Josef,Hinderberger, Dariush,Binder, Wolfgang H.
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supporting information
p. 7820 - 7827
(2021/03/01)
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- Ubiquitous Nature of Rate Retardation in Reversible Addition-Fragmentation Chain Transfer Polymerization
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Reversible addition-fragmentation chain transfer (RAFT) polymerization is one of the most powerful reversible deactivation radical polymerization (RDRP) processes. Rate retardation is prevalent in RAFT and occurs when polymerization rates deviate from ideal conventional radical polymerization kinetics. Herein, we explore beyond what was initially thought to be the culprit of rate retardation: dithiobenzoate chain transfer agents (CTA) with more active monomers (MAMs). Remarkably, polymerizations showed that rate retardation occurs in systems encompassing the use of trithiocarbonates and xanthates CTAs with varying monomeric activities. Both the simple slow fragmentation and intermediate radical termination models show that retardation of all these systems can be described by using a single relationship for a variety of monomer reactivity and CTAs, suggesting rate retardation is a universal phenomenon of varying severity, independent of CTA composition and monomeric activity level.
- Bradford, Kate G. E.,Petit, Leilah M.,Whitfield, Richard,Anastasaki, Athina,Barner-Kowollik, Christopher,Konkolewicz, Dominik
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supporting information
p. 17769 - 17777
(2021/11/10)
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- Tert-amyl methyl ether preparation method and light gasoline modification method
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The invention discloses a tert-amyl methyl ether preparation method and a light gasoline modification method. The tert-amyl methyl ether preparation method comprises that methanol and isopentene contact an etherification catalyst under an etherification reaction condition to obtain the reaction product containing tert-amyl methyl ether, wherein the etherification catalyst is a polymer supported ionic liquid catalyst, and has a structure represented by a formula (I) or a formula (II). With the method of the present inventin, the tert-amyl methyl ether preparation reaction can maintain the highreactivity.
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Paragraph 0087; 0089
(2018/06/14)
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- Multistimuli-responsive hydrogel particles prepared via the self-assembly of PEG-based hyperbranched polymers
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Generally, it is very difficult to obtain multistimuli-responsive hydrogel particles. Here, we introduce a novel method for the preparation of multistimuli-responsive hydrogel particles by adding water into the poly(ethylene glycol) (PEG)-based hyperbranched polymers. The produced PEG-base polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization become temperature-sensitive and less soluble when heated above the lower critical solution temperature (LCST) after directly adding water. Subsequently, the hydrogel particles can be formed via hyperbranch-hyperbranch coupling through disulfide exchange. The resulting hydrogel particles are temperature-, photo-, and redox-responsive.
- Chen, Qian-Bao,You, Ye-Zi
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supporting information
p. 677 - 679
(2015/05/27)
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- Photo-induced electron transfer in a pyrenylcarbazole containing polymer-multiwalled carbon nanotube composite
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A polymer incorporated with a pyrenylcarbazole pendant poly(12-(3-(pyren-1- yl)-carbazol-9-yl)dodecyl methacrylate, denoted as PCP) was synthesized and applied in the functionalization of multi-walled carbon nanotubes (MWCNTs) by noncovalent π-π interaction. The PCP-MWCNT hybrids were isolated and characterized by SEM, TEM, and UV-visible absorption and emission spectroscopies. The strong interaction between PCP and the MWCNT in a 1,1,2,2-tetrachloroethane (TCE) solution was studied. It demonstrated an effective quenching effect on emission from PCP by the MWCNTs. DFT calculations showed electron delocalization between the pyrene and carbazole moieties. The LUMO of PCP is mainly located on the pyrene moiety while the LUMO + 1 is predominantly positioned on the carbazole moiety. Femtosecond transient absorption (TA) experiments determined the characteristic TA peaks of the excited states, which have contributions from both the pyrene and carbazole moieties. The excited state lifetime of the polymer PCP was measured to be 659 ps and the photo-excited electrons were injected into the MWCNTs very effectively on a time scale of 420 fs.
- Yu, Lihong,Lo, Kin Cheung,Xi, Jingyu,Phillips, David Lee,Chan, Wai Kin
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p. 1833 - 1842
(2013/06/27)
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- First RAFT polymerization of captodative 2-acetamidoacrylic acid (AAA) monomer: An experimental and theoretical study
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A capto-dative monomer, 2-acetamidoacrylic acid (AAA), was homopolymerized through RAFT polymerization method using 2-(2-cyanopropanyl dithiobenzoate) (CPDB) as a chain transfer agent and AIBN free radical initiator in DMF at 70 C. DFT calculations were performed in the selection of the CTA for this unique monomer as well as to elucidate the influence of cd-stabilized growing radical on the kinetic parameters in comparison to methacrylic acid (MAA) and N-(prop-1-en-2-yl)acetamide (NPAA), which represent the captive and dative groups of AAA, respectively. Keq for these three monomers is in the order of AAA β > k-add for NPAA and MAA, for AAA k-add is about four orders of magnitude larger than kβ. This is the major disadvantage in the RAFT process of AAA using CPDB. Yet, poly(AAA) could be achieved with PDI as low as 1.49. Molecular weight of the polymer can be tuned by the monomer/AIBN ratio. First block copolymers of AAA with MAA and MMA using poly(AAA) as a macro-CTA were also synthesized, indicating the presence of active chain ends.
- Dedeo?lu, Burcu,U?ur, Ilke,De?irmenci, Isa,Aviyente, Viktorya,Bar?in, Bilin?,?ayli, G?khan,Acar, Havva Yagci
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p. 5122 - 5132
(2013/09/02)
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- Hybrid assemblies based on a gadolinium-containing polyoxometalate and a cationic polymer with spermine side chains for enhanced mri contrast agents
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Supramolecular assembly: Spherical and stable hybrid assemblies based on a cationic polymer with spermine side chains and an anionic Gd3+- containing polyoxometalate cluster (GdW) are prepared by electrostatic interaction (see figure). The T1-weighted MRI performance of GdW is enhanced about three times in the assemblies; meanwhile, the assemblies show good biocompatibility, which enables them to be promising candidates for MRI contrast agents. Copyright
- Chai, Wenqiang,Wang, Shan,Zhao, Hang,Liu, Guifeng,Fischer, Karl,Li, Haolong,Wu, Lixin,Schmidt, Manfred
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supporting information
p. 13317 - 13321
(2013/10/08)
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- NOVEL CHAIN TRANSFER AGENT AND EMULSION POLYMERIZATION USING THE SAME
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To provide a novel compound having both a surface-activating ability and a polymerization controlling ability. A compound represented by the following general formula (1) or (2): wherein, R1 and R3 are an organic group having the hyd
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Page/Page column 14
(2012/12/14)
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- Radical-induced oxidation of RAFT agentsa - A kinetic study
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Radical-induced oxidation of reversible addition-fragmentation chain transfer (RAFT) agents is investigated with respect to the effect of molecular structure on oxidation rate. The radicals are generated by homolysis of either azobisisobutyronitrile or alkoxyamine and transformed in situ immediately into peroxy radicals through transfer to molecular oxygen. It is found that the oxidation rate depends on the structure of Z- and R-group of thiocarbonylthio compounds. For dithioesters with identical Z-phenyl substituent, the oxidation rate decreases in the order of cyanoisopropyl (-C(Me)2CN) > cumyl (-C(Me)2Ph) > phenylethyl (-CH(Me)Ph) > 2-methoxy-1-methyl-2- oxoethyl (-CH(Me) -C(=O)OCH3) > benzyl (-CH2Ph). For dithioesters with identical R-group, the oxidation rate decreases in the order of Z = phenyl- ~ benzyl- > RS- (trithiocarbonates) > RO- (xanthates). The stability of the RAFT agents toward oxidation correlates well with the chain transfer abilities as those previously reported by Rizzardo and coworkers. The priority of the oxidation reaction over the RAFT process, and the subsequent influence on RAFT polymerization are also investigated.
- Li, Changxi,He, Junpo,Zhou, Yanwu,Gu, Yuankai,Yang, Yuliang
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experimental part
p. 1351 - 1360
(2012/02/14)
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- Synthesis of azobenzene-functionalized star polymers via RAFT and their photoresponsive properties
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Azobenzene-functionalized star polymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. First, azobenzene-functionalized linear macro chain transfer agents (Macro-CTA) were synthesized by RAFT polymerization of 6-[4-(4′-Methoxyphenylazo)phenoxy] hexylmethacrylate (MAz6Mc) using 2-(2′-cyanopropyl)dithiobenzoate (CPDB) as RAFT agent in presence of AIBN as initiator in anisole. Subsequently, star azopolymers were synthesized by polymerization of a difunctional azomonomer, BMA2Az, with resultant Macro-CTA in presence of AIBN as initiator in anisole. Star azopolymers were characterized by GPC and spectroscopic methods. Thermal properties of star azopolymers were determined by DSC and TMA. Molecular weight versus conversion and molecular weight versus polymerization time attest to living polymerization characteristics. Photoisomerization behaviors of star azopolymers were studied by irradiation of both UV and visible light. Surface relief gratings were inscribed on star azopolymer films upon exposure to an interference pattern of (RCP + RCP) Ar+ laser. A diffraction efficiency of 20% was obtained by exposure of Star-8 K(2.6 K) polymer film to an (RCP + RCP) Ar+ laser for about 30 min. Surface relief grating structures were investigated by AFM and polarized optical microscopy.
- Alam, Md. Zahangir,Shibahara, Akihisa,Ogata, Tomonari,Kurihara, Seiji
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experimental part
p. 3696 - 3703
(2012/02/05)
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- Simplification of the synthesis of the reversible addition-fragmentation chain transfer agent 2-(2-cyanopropyl)-dithiobenzoate
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The general literature procedure for the preparation of the reversible addition-fragmentation chain transfer (RAFT) agent 2-(2-cyanopropyl)- dithiobenzoate (CPDB) was modified by omitting the recrystallisation of the intermediate di(thiobenzoyl)disulphide. The yield of the CPDB in the simplified synthesis was increased four times compared to the standard one. The behaviour of the CPDB obtained by the modified procedure and by the standard one in the polymerisation of methyl methacrylate was investigated. The CPDB synthesized by the simplified procedure showed itself to be a good RAFT agent, giving excellent control over the polymerisation of methyl methacrylate and it behaved in the same manner as the CPDB prepared by the literature method. The obtained poly(methyl methacrylate) had a narrow molecular weight distibution (PD = 1.1).
- Milovanovic, Milos B.,Avramovic, Milena,Katsikas, Lynne,Popovic, Ivanka G.
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experimental part
p. 1711 - 1719
(2011/10/02)
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- Morphology transitions in RAFT polymerization
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Polymerization-induced self-assembly and re-organization (PISR) was used to prepare polymeric nanostructured materials with a variety of morphologies. Reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene in a selective solvent
- Cai, Weimin,Wan, Wenming,Hong, Chunyan,Huang, Chuanqun,Pan, Caiyuan
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experimental part
p. 5554 - 5561
(2012/01/06)
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- Process for the preparation of graft copolymers by Reversible Addition Fragmentation Chain Transfer (RAFT) and Ring Opening Polymerisation (ROP)
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A combined RAFT/ROP process for the preparation of a graft co-polymer having a backbone built-up from repeating units derived by polymerization of free-radically polymerizable monomers comprising vinylic monomers, and polyester side chains grafted to said backbone derived by ring-opening polymerisation of cyclic ester compounds; said process comprising reacting a mixture of (a) one or more vinylic monomers, optionally in combination with other monomers susceptible to free-radical polymerization, wherein at least one of said vinylic monomers comprises a (free) hydroxyl group; (b) a thiocarbonylthio compound as chain transfer agent; (c) one or more cyclic esters, which is/are susceptible to a ring-opening polymerization; and (d) a compound effective for initiating the ring-opening polymerization of the one or more cyclic esters; and reacting said mixture in an inert solvent at a temperature of more than 90°C under exclusion of oxygen to form the graft copolymer.
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- Ultra-fast microwave enhanced reversible addition-fragmentation chain transfer (RAFT) polymerization: Monomers to polymers in minutes
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Microwave mediated RAFT polymerization leads to ultra-fast polymerizations, whilst keeping excellent control over molecular weights and molecular weight distributions; this is the first example of such a dramatic effect of microwaves on living radical polymerization kinetics, and it shows the potential for chemists to produce very well controlled polymers in a matter of minutes. The Royal Society of Chemistry.
- Brown, Steven L.,Rayner, Christopher M.,Graham, Susan,Cooper, Andrew,Rannard, Steven,Perrier, Sebastien
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p. 2145 - 2147
(2008/02/09)
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- Thiocarbonylthio compounds [S=C(Ph)S-R) in free radical polymerization with reversible addition-fragmentation chain transfer (RAFT polymerization). Role of the free-radical leaving group (R)
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Radical polymerization with reversible addition-fragmentation chain transfer (RAFT polymerization) can be used to synthesize a wide range of polymers of controlled architecture and narrow molecular weight distribution. The polymerization use addition-frag
- Chong, Bill Y. K.,Krstina, Julia,Le, Tam P.T.,Moad, Graeme,Postma, Almar,Rizzardo, Ezio,Thang, San H.
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p. 2256 - 2272
(2007/10/03)
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- Reaction of cyclic tetrathiophosphates with carboxylic acids as a means to generate dithioesters and control radical polymerization by RAFT
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Radical control: Controlled free-radical polymerization of styrene and methyl (meth)acrylate is achieved by using Davy reagents or P4S10 in conjunction with benzoic acid, which leads to in situ formation of dithioesters that act as chain-transfer agents and thus control the reaction. In the case of P4S10/PhCOOH, d[thiobenzoic acid is the key intermediate in this process (see scheme).
- Dureault, Alex,Gnanou, Yves,Taton, Daniel,Destarac, Mathias,Leising, Frederic
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p. 2869 - 2872
(2007/10/03)
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- A new facile synthesis of tertiary dithioesters
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Thermal decomposition of tertiary azo compounds in the presence of a triphenylmethyl dithioester results in the formation of the corresponding tertiary dithioesters. This procedure is especially useful for the synthesis of tertiary phosphoryldithioformate
- Alberti, Angelo,Benaglia, Massimo,Laus, Michele,Sparnacci, Katia
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p. 7911 - 7914
(2007/10/03)
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- POLYMERIZATION WITH LIVING CHARACTERISTICS
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This invention concerns a free radical polymerization process, selected chain transfer agents employed in the process and polymers made thereby, in which the process comprises preparing polymer of general Formula (A) and Formula (B) comprising contacting: (i) a monomer selected from the group consisting of vinyl monomers (of structure CH2═CUV), maleic anhydride, N-alkylmaleimide, N-arylmaleimide, dialkyl fumarate and cyclopolymerizable monomers; (ii) a thiocarbonylthio compound selected from Formula (C) and Formula (D) having a chain transfer constant greater than about 0.1; and (iii) free radicals produced from a free radical source; the polymer of Formula (A) being made by contacting (i), (ii) C and (iii) and that of Formula (B) by contacting (i), (ii) D, and (iii); and (iv) controlling the polydispersity of the polymer being formed by varying the ratio of the number of molecules of (ii) to the number of molecules of (iii); wherein Q, R, U, V, Z, Z′, m, p and q are as defined in the text.
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