201611-77-0Relevant articles and documents
Facile synthesis of thiol-terminated poly(styrene-ran-vinyl phenol) (PSVPh) copolymers via reversible addition-fragmentation chain transfer (RAFT) polymerization and their use in the synthesis of gold nanoparticles with controllable hydrophilicity
Lee, Chang-Uk,Roy, Debashish,Sumerlin, Brent S.,Dadmun, Mark D.
, p. 1244 - 1251 (2010)
A facile approach to prepare thiol-terminated poly(styrene-ran-vinyl phenol) (PSVPh) copolymers and PSVPh-coated gold nanoparticles is reported with the goal of creating stabilizing ligands for nanoparticles with controlled hydrophilicity. Dithioester-ter
Pt nanoparticles stabilized by thermosensitive polymer as effective and recyclable catalysts for the asymmetric hydrogenation of ethyl pyruvate
Yu, Wenjun,Lou, Lan-Lan,Yu, Kai,Li, Shanshan,Shi, Yang,Liu, Shuangxi
, p. 52500 - 52508 (2016/06/13)
Thermosensitive and thiol-terminated poly(N-isopropylacrylamide)s (PNIPAM-SHs) were synthesized and used to stabilize Pt nanoparticles. After chiral modification with cinchonidine, these nanocatalysts were firstly applied in the asymmetric hydrogenation of ethyl pyruvate. The influences of reaction solvent, chiral modifier concentration, hydrogen pressure, mean molecular weight and amount of polymer on the catalytic performance were investigated. These colloidal Pt catalysts exhibited remarkably high catalytic activity and enantioselectivity. Especially, high turnover frequencies up to 17:820 h-1 were achieved, which is the best result for this reaction with regard to the colloidal Pt catalysts. The high catalytic activity was associated with the high hydrophobicity of isopropyl groups in polymer moieties in the catalyst. Moreover, recycling experiments showed that the thermosensitivity of PNIPAM-SH made these colloidal Pt catalysts easier to recover and reuse. Excellent stability and reusability were presented over these catalysts, and no obvious decrease in catalytic activity and enantioselectivity was observed for eleven runs.
Carbohydrate-based amphiphilic diblock copolymers with pyridine for the sensitive detection of protein binding
Otsuka, Hidenori,Hagiwara, Toshiya,Yamamoto, Sayuri
, p. 6764 - 6773 (2015/01/08)
Glycopolymers are useful macromolecules for presenting carbohydrates in multivalent form. Here, amphiphilic block copolymers consisting of hydrophilic lactose and hydrophobic pyridine were synthesized via reversible addition-fragmentation chain transfer polymerization (RAFT). RAFT polymerization of 2-O-methacryloyloxyethyl-(-D-lactoseheptaacetate) (2-O-MALac) was performed using cumyl dithiobenzoate (CDB) as the chain transfer agent to give well-defined glycopolymers. The livingness of the process was further demonstrated by successfully chain-extending one of obtained glycopolymers with 4-pyridyl methyl methacrylate affording narrow dispersed diblocks. With the obtained block copolymers, a glycosurface was generated on the gold surface of quartz crystal microbalance (QCM) through self-assembled strategy by the use of gold affinitive pyridine functional group. Furthermore, the resulting glycosurface was used to detect the binding of lactose specific lectin, ricinus communis agglutinin (RCA120) without non-specific protein adsorption.
Well-defined diblock copolymers possessing fluorescent and metal chelating functionalities as novel macromolecular sensors for amines and metal ions
Demetriou, Maria,Krasia-Christoforou, Theodora
experimental part, p. 52 - 60 (2012/03/27)
The amino- and metal-ion sensing capability of a novel type of well-defined block copolymers based on 9-anthrylmethyl methacrylate (AnMMA; hydrophobic, fluorescent) and 2-(acetoacetoxy)ethyl methacrylate (AEMA; hydrophobic, metal chelating) has been investigated in organic media. AEMAx-b-AnMMA y diblock copolymers were prepared for the first time using reversible addition-fragmentation chain transfer (RAFT) polymerization. All polymers were characterized in terms of molecular weights, polydispersity indices and compositions by size exclusion chromatography and 1H NMR spectroscopy, respectively. The glass transition (Tg) temperatures of the AEMAx and AnMMAx homopolymers and the AEMA x-b-AnMMAy diblock copolymers were determined using differential scanning calorimetry. These systems were evaluated toward their ability to act as effective dual chemosensors (i.e., amino- and metal-ion sensors) in an organic solvent (chloroform). More precisely, the fluorescence intensity of both the AnMMAx homopolymers and the AnMMA x-b-AEMAy diblock copolymers in solution exhibited a significant decrease in the presence of triethylamine. Moreover, the presence of iron (III) cations were also found to significantly affect the fluorescence signal of the anthracene moieties when those were combined in a block copolymer structure with the AEMA units, due to complex formation occurring between the β-ketoester groups of the AEMAx segment and the cations.
Synthesis and characterization of well-defined optically active methacrylic diblock copolymers
Achilleos, Mariliz,Kafouris, Demetris,Holder, Simon J.,Krasia-Christoforou, Theodora
, p. 4215 - 4222 (2012/11/13)
A new, simple, and cost-effective approach toward the development of well-defined optically active diblock copolymers based on methacrylate monomers is described for the first time. Starting from the low-cost optically active (S)-(-)-2-methyl-1-butanol, a new optically active methacrylic monomer, namely, (S)-(+)-2-methyl-1-butyl methacrylate [(S)-(+)-MBuMA], was synthesized. Reversible addition fragmentation chain transfer polymerization was then used for preparing well-defined poly[(S)-(+)-MBuMA] homopolymers and water-soluble diblock copolymers based on [(S)-(+)-MBuMA] and the hydrophilic and ionizable monomer 2-(dimethyl amino)ethyl methacrylate (DMAEMA). The respective homopolymers and diblock copolymers were characterized in terms of their molecular weights, polydispersity indices, and compositions by size exclusion chromatography and 1H NMR spectroscopy. Polarimetry measurements were used to determine the specific optical rotations of these systems. The structural and compositional characteristics of micellar nanostructures possessing an optically active core generated by p((S)-(+)-MBuMA)-b-p(DMAEMA) chains characterized by predetermined molecular characteristics may be easily tuned to match biological constructs. Consequently, the aggregation behavior of the p[(S)-(+)-MBuMA]-b-p[DMAEMA] diblock copolymers was investigated in aqueous media by means of dynamic light scattering and atomic force microscopy, which revealed the formation of micelles in neutral and acidified aqueous solutions.
Thermal decomposition of cumyl dithiobenzoate
Liu, Yang,He, Junpo,Xu, Jiangtao,Fan, Deqin,Tang, Wei,Yang, Yuliang
, p. 10332 - 10335 (2008/02/02)
Thermal decomposition of cumyl dithiobenzoate (CDB), a reagent widely used in controlled polymerization of various monomers, was investigated. CDB was synthesized by flash chromatography followed by recrystallization and obtained as large purple crystals. A close analysis of the MS spectra revealed the presence of isopropylbenzene and cumyl thiobenzoate. Results show that the polymeric dithioesters, which are more stable than CDB, are formed after the initiation period, accounting for the fact that CDB-mediated RAFT polymerization of styrene works well at high temperature.
Process for preparing dithioesters
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Page 4-5, (2010/02/08)
The present invention relates to a process for preparing dithioesters in which a dithiocarboxylic acid and/or a dithiocarboxylic salt is reacted with a vinyl compound and/or an alkyl compound which includes a leaving group, the reaction being carried out in a biphasic system in which one of the phases comprises water and the weight ratio of the aqueous phase to the organic phase lies in the range from 95:5 to 5:95.
POLYMERIZATION WITH LIVING CHARACTERISTICS
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, (2008/06/13)
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.