Ethyl 2-bromoisobutyrate Research Articles

Characterization and optimization of poly(glycidyl methacrylate-co-styrene) synthesized by atom transfer radical polymerization

Styrene (S) and glycidyl methacrylate (GMA) copolymers were synthesized by atom transfer radical polymerization (ATRP) under different conditions. The effect of initiators, ligands, solvents, and temperature to the linear first-order kinetics and polydispersity index (PDI) was investigated for bulk polymerization. First-order kinetics was observed between linearly increasing molecular weight versus conversion and low polydispersities (PDI) were achieved for ethyl 2-bromo isobutyrate (EBiB) as an initiator and N, N′, N′, N″, N″-pentamethyldiethylenetriamine (PMDETA)/CuBr as a catalyst. The copolymers with different compositions were synthesized using different in-feed ratios of monomers. Copolymers composition was calculated from 1H NMR spectra which were further confirmed by quantitative 13C{ 1H} NMR spectra. The monomer reactivity ratios were obtained with the help of Mayo–Lewis equation using genetic algorithm method. The values of reactivity ratios for glycidyl methacrylate and styrene monomers are r G = 0.73 and r S = 0.42, respectively.

Polymers from renewable resources: Bulk ATRP of fatty alcohol‐derived methacrylates

AbstractCopper‐mediated atom transfer radical polymerization (ATRP) of lauryl methacrylate (LMA) and other long‐chain methacrylates was investigated in bulk at 35 °C by using CuCl/N,N,N′,N′,N′′‐pentamethyldiethylenetriamine (PMDETA)/tricaprylylmethylammonium chloride (Aliquat®336) as the catalyst system and ethyl 2‐bromoisobutyrate (EBIB) as the initiator. The investigated monomers can be derived from fatty alcohols and are therefore an important renewable resource for a sustainable development of our future. The amounts of ligand, Aliquat®336 and CuCl were optimized and the effect of their concentrations on the control of the polymerization and the observed conversions were investigated. It was found that a molar ratio of EBIB/CuCl/Ligand/Aliquat®336 of 1 : 1 : 3 : 1 provided the highest conversions of LMA and the best controlled polymerizations. These optimized conditions allowed for the synthesis of poly(lauryl methcarylate)s with different targeted DP (25, 50, 75, 100, 120, 240, and 500), including high‐molecular‐weight polymers with narrow molecular weight distributions. In addition, methacrylate monomers were prepared from fatty alcohols (capric, myristic, palmitic, stearic) and polymerized using the developed procedure to obtain polymers with the same DP and different chain lengths (C10, C12, C14, C16, and C18) of pending alkyl groups. Finally, the thermal properties of these polymers were examined by differential scanning calorimetry and thermogravimetric analysis.

Synthesis and characterization of original 2-(dimethylamino)ethyl methacrylate/poly(ethyleneglycol) star-copolymers

Novel synthetic transfection vectors with linear triblock and star-shaped diblock copolymer architectures have been synthesized by atom transfer radical polymerization (ATRP). Based on 2-(dimethylamino)ethyl methacrylate (DMAEMA) and copolymerization with poly(ethyleneglycol) α-methoxy, ω-methacrylate (MAPEG), the synthesis was realized using CuBr ligated with 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA) as catalytic complex and either ethyl 2-bromoisobutyrate (EB iB) or bis(α-bromoisobutyryl) N-methyl diethanolamine (DEA) or tris(α-bromoisobutyryl) triethanolamine (TEA) as (multifunctional)initiator. The polymers were characterized by GPC and NMR. The solution properties of these homopolymers and palm-tree-like copolymers were investigated by viscometry either in pure water or in buffered aqueous solutions. Interestingly, all the synthesized polymers show polyelectrolyte effect in Millipore water (25 °C) and in Hepes (20 mM) buffer solution (pH 7.4, NaCl 155 mM, 25 °C). Fitting of these viscometric data according to either Fuoss or Fedors equation allows for calculating the intrinsic viscosity of the polymers. These results are compared with dynamic light scattering (DLS) experiments to determine absolute masses. Finally, DEA based palm-tree-like copolymer is investigated to AFM measurement and micelles were observed at pH 8.

ATRP of 3-(triethoxysilyl)propyl methacrylate and preparation of “stable” gelable block copolymers

ATRP of a gelable monomer, 3-(triethoxysilyl)propyl methacrylate (TESPMA), mediated by CuBr/ N, N, N’, N’’, N”-pentamethyldiethylenetriamine (PMDETA) using ethyl 2-bromoisobutyrate (2-EBiB) as initiator was studied. The results indicate that polymerization follows the first-order kinetic. PolyTESPMA (PTESPMA) is much more stable to moisture which is important for exploring the properties of its block copolymer. A series of PEO- b-PTESPMA block copolymers with different composition were prepared. Self-assembly of PEO- b-PTESPMA has also been explored in a mixture of methanol and water and polymeric vesicles have been obtained. By introducing the gelation catalyst, the block copolymer vesicles can be stabilized by the silica networks.

PEO-Based Block Copolymers and Homopolymers as Reactive Surfactants for AGET ATRP of Butyl Acrylate in Miniemulsion

Amphiphilic block copolymers poly(ethylene oxide)-b-polystyrene (PEO-PS-Br) with various molecular weights and poly(ethylene oxide) homopolymer (PEO-Br) were synthesized and used as macroinitiators and stabilizers (reactive “surfactants”) for activator generated by electron transfer atom transfer radical polymerization (AGET ATRP) of n-butyl acrylate (BA), in miniemulsion either with or without ethyl 2-bromoisobutyrate (EBiB) as co-initiator. Under both conditions, the reactions were well controlled and stable latexes were formed. In the absence of EBiB, polymer particles with diameter around 120−230 nm were obtained, and the particles contained polymers with molecular weight Mn = 16 000−25 000 g/mol and relatively low polydispersity (Mw/Mn = 1.2−1.4). In the presence of a low molecular weight initiator, EBiB, the amount of surfactant used can be reduced in the reaction (1.7−4 wt % vs monomer). The percent of initiating sites from EBiB was changed from 30% to 90%, and the majority of the obtained polymers...

Atom transfer radical copolymerization of glycidyl methacrylate and allyl methacrylate, two functional monomers

Bi-functional statistical copolymers, based on allyl methacrylate (AMA) and glycidyl methacrylate (GMA), were synthesized via atom transfer radical polymerization (ATRP). The polymerization reactions were carried out in a diphenyl ether solution at low temperature, 50 °C, using ethyl 2-bromoisobutyrate (EBrIB) as an initiator, and copper chloride with N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) as the catalyst. Different aspects of the copolymerization, such as the kinetic behaviour, crosslink density and gel fraction were studied. The sol fractions of the synthesized copolymers were characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. The reactivity ratios were calculated from the copolymer composition, determined by 1H NMR, and using the extended Kelen–Tüdös method. Values of 0.82 ± 0.04 and 1.22 ± 0.03 were obtained for AMA and GMA, respectively. The copolymer composition as a function of conversion degree for the different monomer molar fractions in the feed agreed with the theoretical values calculated from the Mayo–Lewis terminal model (MLTM).

Novel ionic liquids as reaction medium for ATRP of acrylonitrile in the absence of any ligand

Atom transfer radical polymerization (ATRP) of acrylonitrile (AN) with ethyl 2-bromoisobutyrate (EBiB) as the initiator was firstly approached in the absence of any ligand in three novel ionic liquids, 1-methylimidazolium acetate ([mim][AT]), 1-methylimidazolium valerate ([mim][VT]) and 1-methylimidazolium caproate ([mim][CT]), respectively. All the polymerizations in the ionic liquids proceeded in a well-controlled manner. The polymerization in [mim][AT] not only showed the best control of molecular weight and its distribution but also provided a rather rapid reaction rate with the molar ratio of [AN]:[FeBr2]:[EBiB] at 200:2:1. The resulting polyacrylonitrile was successfully used as the macroinitiator to proceed the chain extension polymerization in [mim][AT]. After simple purification, all the ionic liquids and FeBr2 could be recycled and reused and had no effect on the living nature of polymerization.

A novel electrosynthesis cell with a compressed graphite powder cathode and minimal organic solvent content: Application to the Reformatsky reaction

A Reformatsky reaction has been employed as a model by which to highlight the advantages of a novel type of undivided electrosynthesis cell working with a content of organic solvent at least 10-times lower than that used in conventional cells. The cathode was formed from compressed graphite powder and was impregnated with a mixture of ethyl 2-bromoisobutyrate and benzaldehyde dissolved in a minimal volume of organic solvent. The cell was filled with aqueous KBr solution, and the electrolysis carried out at a constant potential corresponding to the reduction of the bromoester. Several parameters were optimized with respect to the yield of coupling product, including the ratio of bromoester to benzaldehyde, the pressure of compaction of the electrode powder inside the cavity, and the influence of the cathodic material. Ethyl 2,2-dimethyl-3-hydroxy-3-phenylpropionate was obtained in a yield of up to 86%, and ethyl isobutyrate was the only by-product. A number of other model substrates have been investigated in order to determine the scope and limitations of this new methodology.

ARGET ATRP Synthesis of Thermally Responsive Polymers with Oligo(ethylene oxide) Units

Ethyl 2-bromoisobutyrate (EBiB), tin (II) 2-ethylhexanoate (Sn(EH)2), copper(II) bromide, and solvents were purchased from Aldrich at the highest purity available and used as received without further purification. Di(ethylene glycol) methyl ether methacrylate (MEO2MA) (Aldrich, 95%) was purified by vacuum distillation before use. The ligand, tris[(2-pyridyl)methyl]amine (TPMA), was prepared according to the reported procedure.

A New Strategy for Preparation of Graft Copolymers via “Graft onto” by Atom Transfer Nitroxide Radical Coupling Chemistry: Preparation of Poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl-co-ethylene oxide)-graft-polystyrene and Poly(tert-butyl acrylate)

A series of graft copolymers poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl-co-ethylene oxide)-graft-polystyrene or poly(tert-butyl acrylate) [poly(GTEMPO-co-EO)-g-PS/PtBA] were synthesized by atom transfer nitroxide radical coupling (ATNRC) chemistry. Linear precursor copolymers with multipending 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) groups [poly(GTEMPO-co-EO)] were prepared first by anionic ring-opening copolymerization of 4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (GTEMPO) and ethylene oxide (EO), and then polystyrene (PS) and poly(tert-butyl acrylate) (PtBA) with bromide end group were obtained by atom transfer radical polymerization (ATRP) using ethyl 2-bromoisobutyrate (EBiB) as the initiator and CuBr/N,N,N′,N′,N′′-pentamethyldiethylenetriamine (PMDETA) as catalyst. When the linear precursor copolymer poly(GTEMPO-co-EO) was mixed with PS or PtBA chains and heated to 90 °C in the presence of CuBr/PMDETA, the formed secondary carbon radicals at the PS or PtBA chain ends were qu...

Rapid ambient temperature atom transfer radical polymerization of tert‐butyl acrylate

AbstractBACKGROUND: Atom transfer radical polymerization (ATRP) is considered to be one of the better and easier synthetic tools for the preparation of polymers with controlled molecular weights and polydispersities. Ambient temperature ATRP of tert‐butyl acrylate (tBA) was studied in a detailed manner with ethyl 2‐bromoisobutyrate (EBrB) and tert‐butyl 2‐bromoisobutyrate (tBuBrB) as the initiators for three different degrees of polymerization.RESULTS: Details pertaining to the kinetics of polymerization using different initiators are reported. It is observed that dimethylsulfoxide accelerates the polymerization at room temperature. The use of Cu(II) as the deactivator produces very narrow dispersity polymers. A diblock copolymer, poly(tert‐butyl acrylate)‐block‐poly(methyl methacrylate), was synthesized from the poly(tBA) macroinitiator demonstrating the controlled living nature of the polymerizations.CONCLUSIONS: The rate of polymerization is more rapid with a secondary initiator (ethyl 2‐bromopropionate) compared to the tertiary initiators EBrB and tBuBrB. From the detailed kinetic results it is observed that tris(2‐dimethylaminoethyl)amine was a better ligand compared to tris(2‐aminoethyl)amine in terms of achieving controlled polymerization. Copyright © 2007 Society of Chemical Industry

Synthesis and characterization of low molecular weight poly(methyl acrylate)-b-polystyrene by a combination of ATRP and click coupling method

The combination of atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of well-defined block copolymers. Bromo terminated poly(methyl acrylate) (pMA-Br) was prepared by an ATRP initiator, ethyl-2-bromoisobutyrate (EBiB). Subsequently, the bromine chain end of pMA-Br was converted to an azide group by simple nucleophilic substitution reaction. α-Alkyn-ω-bromo-functionalized polystyrene was also synthesized by ATRP using the alkyn-functionalized initiator, propargyl-2-bromoisobutyrate (PgBiB). In both cases, the conversion was limited to a low level to ensure a high degree of chain end functionality. Then the coupling reaction between the azide end group in pMA-N3 and alkyn-functionalized PgBiB-pSt was performed by Cu(I)catalysis. This coupling reaction was monitored by gel permeation chromatography (GPC). The synthesized block copolymer was characterized by FT-IR,1H-NMR spectroscopy and1H-1H COSY correlation spectroscopy.

Synthesis of AB‐type block copolymers containing benzoxazole and anthracene groups by ATRP and fluorescent property

AbstractTwo functional monomers, methacrylic acid 4‐(2‐benzoxazol)‐benzyl ester (MABE) containing the benzoxazole group and 4‐(2‐(9‐anthryl))‐vinyl‐styrene (AVS) containing the anthracene group were synthesized by rational design. The MABE was polymerized via atom transfer radical polymerization (ATRP) using ethyl 2‐bromoisobutyrate (EBIB) as initiator in CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) catalyst system; block copolymers poly(MABE‐b‐AVS) was obtained, which was conducted by using poly(MABE) as macro‐initiator, AVS as the second monomer, and CuBr/PMDETA as catalyst. The constitute of two monomers in block copolymers poly(MABE‐b‐AVS) by ATRP could be adjusted, that is the constitute of the benzoxazole group and the anthracene group could be controlled in AB‐type block copolymers. Moreover, the fluorescent properties of homopolymers poly(MABE) and block copolymers poly(MABE‐b‐AVS) were discussed herein. With the excitation at λex = 330 nm, the fluorescent emission spectrum of poly(MABE) solution showed emission at 375 nm corresponding to the benzoxazole‐based part; with the same excitation, the fluorescent emission spectrum of poly(MABE‐b‐AVS) solution showed a broad peek at 330–600 nm when the monomer AVS to the total monomers mole ratio was 0.31, and the fluorescent emission spectrum of poly(MABE‐b‐AVS) in film state only showed one peak at 525 nm corresponding to the anthracene‐based unit that indicated a complete energy transfer from the benzoxazole group to the anthracene group. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3894–3901, 2007

Iron catalyzed atom transfer radical polymerization of methyl methacrylate using diphenyl-2-pyridylphosphine as a ligand

The living radical polymerization of methyl methacrylate (MMA) by atom transfer radical polymerization, (ATRP) employing a Fe(II)X2/diphenyl-2-pyridyl phosphine (PyP) catalytic system (X = Cl, Br ), was investigated using several initiators and solvents at various temperatures. Most of the polymerizations with the PyP ligand were well controlled, with a linear increase in the number average molecular weights (Mn) vs. conversion, with relatively low molecular weight distributions (Mw/Mn = 1.2–1.4) throughout the reactions. The measured weights matched those of the predicted values. The ethyl-2-bromoisobutyrate (EBriB) initiated ATRP of MMA, with the Fe(II)X2/diphenyl-2-pyridyl phosphine catalytic system (X = Cl, Br), was better controlled in p-xylene at 80°C than the other solvents used in this study.

Synthesis of Polystyrene with Terminal Functional Groups via Atom Transfer Radical Polymerization using an Immobilized Catalytic System

A new cross-linked solid catalyst with azo-crown ether functional side chains (PSt-1,10-dicarbonyl-3,6,9-trizaocylcodecane) was prepared under microwave irradiation and its structure was characterized using Fourier transform infrared (FT-IR) spectroscopy, elemental analysis and solid-state 13 C NMR. The immobilized catalyst system, composed of functionalized lightly cross-linked polystyrene (crosslink degree, 3.5%), CuBr and ethyl-2-bromoisobutyrate (EBiB), was used to perform the atom transfer radical polymerization (ATRP) of styrene. The polymer obtained had functional end groups that can coordinate with rare earth ions such as La(III). Thus the polymer was reacted with La(NO3 )3 and the resulting polystyrene-La complex was characterized by FT-IR and X-ray photoelectron spectroscopy. The polystyrene-La complex exhibited an increase in third-order nonlinear optical properties as determined by the degenerated four wave mixing technique.

Cu(II)‐Mediated ATRP of MMA by Using a Novel Tetradentate Amine Ligand with Oligo(ethylene glycol) Pendant Groups

AbstractA novel tetradentate amine ligand namely N,N,N′,N″,N‴;,N‴;‐hexaoligo(ethylene glycol) triethylenetetramine (HOEGTETA) was employed in the homogenous ATRP of MMA in anisole using CuBr and CuBr2 as the catalyst and ethyl 2‐bromoisobutyrate (EBiB) as an initiator. The effect of the polymerization temperature and the various ratios of Cu(I) to Cu(II) were investigated in detail. Moreover, we demonstrated the ATRP of MMA by using only Cu(II) in the absence of any free radical initiator, reducing agent, or air. The ATRP of MMA with the use of only Cu(II) and HOEGTETA or N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) resulted in well‐defined PMMA.magnified image

Novel ionic liquids as reaction medium for atom transfer radical polymerization of methyl methacrylate

Atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) employing ethyl 2-bromoisobutyrate (EBiB)/CuBr as the initiating system was investigated at 50 °C in the absence of any additional ligand in the three room temperature ionic liquids (RTILs), 1-methyl-imidazolium acetate ([mim][CH 3COO]), 1-methylimidazolium propionate ([mim][CH 3CH 2COO]) and 1-methylimidazolium butyrate ([mim][CH 3CH 2CH 2COO]), respectively. All the polymerization in the three RTILs proceeded in a well-controlled manner. The sequence of the apparent polymerization rate constants was k app([mim][CH 3COO]) > k app([mim][CH 3CH 2COO]) > k app ([mim][CH 3CH 2CH 2COO]).

Linear and Hyperbranched Glycopolymer-Functionalized Carbon Nanotubes: Synthesis, Kinetics, and Characterization

Linear and hyperbranched glycopolymers, a kind of sugar-containing polymers, were grown successfully from surfaces of multiwalled carbon nanotubes (MWNTs) by the “grafting from” strategy with good controllability and high reproducibility. Linear glycopolymer was grafted from the surfaces of MWNTs by surface-initiated atom transfer radical polymerization (ATRP) of 3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-d-glucofuranose (MAIG) with CuIBr/HMTETA (1,1,4,7,10,10-hexamethyltriethylenetetramine) at 60 °C in ethyl acetate. After hydrolysis of polyMAIG in 80 wt % formic acid for 48 h, water-soluble poly(3-O-methacryloyl-α,β-d-glucopyranose) (polyMAG)-grafted MWNTs were obtained. The kinetics were investigated by carrying out the polymerizations using 2-bromo-2-methylpropionyl-immobilized MWNTs (MWNT−Br) as the macroinitiator in the absence or presence of ethyl 2-bromoisobutyrate as sacrificial initiator. In both cases a linear dependence of molecular weight on conversion was obtained, and the polymer amounts grafted on MWNTs could be well controlled in a wide range by the reaction time and monomer conversion. Coupling was found in the GPC curves of free polymer when the conversion of monomer reached ca. 45−50%. This clearly indicates that coupling reactions are more predominant than the conventional ATRP in a homogeneous solution without CNTs, where no coupling occurred despite of very high conversion of this monomer (>80%). Hyperbranched glycopolymers (HPGs) were also grafted from the surfaces of MWNTs by self-condensing vinyl copolymerization (SCVCP) of the monomer, MAIG, and inimer, 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEMA, AB*) via ATRP with bis(triphenylphosphine)nickel(II) bromide ((PPh3)2NiBr2) at 100 °C in ethyl acetate. After deprotection in formic acid, hyperbranched glycopolymers with high density of hydroxyl groups functionalized MWNTs were achieved. The novel water-soluble biocompatible glycopolymer-grafted CNTs have fascinating potentials in the fields of tissue engineering and bionanomaterials.

Controlled Radical Polymerization of 2,3‐Epithiopropyl Methacrylate

AbstractWe report first results on the controlled radical polymerization of 2,3‐epithiopropyl methacrylate (ETMA) also known as thiiran‐2‐ylmethyl methacrylate. Reversible addition‐fragmentation chain transfer (RAFT) of ETMA was carried out in bulk and in solution, using AIBN as initiator and the chain transfer agents: cyanopropyl dithiobenzoate (CPDB) and cumyl dithiobenzoate (CDB). A linear increase of the number‐average molecular weight and decrease of the polydispersity with monomer conversion were observed using CPDB as transfer agent, indicating a controlled process. Atom transfer radical polymerization (ATRP) of ETMA was performed under different reaction conditions using copper bromide complexed by tertiary amine ligands and ethyl 2‐bromoisobutyrate (EBiB) or 2‐bromopropionitrile (BPN) as initiator. All experiments lead to a crosslinked polymer. Preliminary studies in the absence of initiator showed that the CuBr/ligand complex alone initiates the ring‐opening polymerization of thiirane leading to a poly(propylene sulfide) with pendant methacrylate groups.magnified image

Gelation-free synthesis of poly(allyl methacrylate- co-butyl acrylate) copolymers by atom transfer radical polymerization

The preparation of functional copolymers based on allyl methacrylate (AMA) and butyl acrylate (BA) without gel formation via atom transfer radical polymerization is described. The gelation-free controlled radical copolymerizations were carried out in benzonitrile solution at 70 °C using ethyl 2-bromoisobutyrate as initiator and mixed halogen technique, copper chloride along with N, N, N′, N″, N″-pentamethyldiethylenetriamine as the catalyst system. Kinetic analyses have demonstrated that all the copolymerizations showed a general behaviour characterized by two clearly differentiated stages. Thus, in an initial stage, the polymerizations presented first order kinetic with respect to the monomer concentration. In the subsequent stage, at low-intermediate conversions, a deceleration in the rate copolymerization leads to limit conversions, which decrease as the initial concentration of BA in the feed increases. The reactivity ratios values were calculated from the copolymer composition determined by 1H NMR, and using the extended Kelen–Tüdös method. Values of 2.70 ± 0.21 and 0.49 ± 0.04 were obtained for AMA and BA, respectively. The cumulative copolymer compositions as a function of conversion degree for the different monomer molar fractions in the feed showed gradient character of the copolymers obtained.