Atom Transfer Radical Polymerization Of Styrene Research Articles

Synthesis and characterization of poly(styrene‐co‐butyl acrylate)/clay nanocomposite latexes in miniemulsion by AGET ATRP

AbstractPolymer/clay nanocomposite latexes in the form of positively charged nanoparticles were synthesized by a newly developed initiating system, activators generated by electron transfer (AGET), which has been employed in atom transfer radical polymerization (ATRP). These clay‐dispersed latexes were synthesized using AGET ATRP of styrene and butyl acrylate in a miniemulsion system in which, ascorbic acid as a reducing agent was added drop wise to reduce termination reactions. Particle size and particle size distribution of resulted nanocomposite latexes were characterized by dynamic light scattering (DLS). These latexes were in the range of 138 to 171 nm in size. Gel permeation chromatography (GPC) was used to characterize the molecular weight and molecular weight distribution of the resultant copolymer nanocomposites. GPC traces showed that polymers of narrow molecular weight distribution and low Polydispersity Index (PDI) have been synthesized; this clearly shows ATRP reaction is conducted successfully. By increasing nanoclay content, molecular weight of the nanocomposites decreases. The presence of the nanofiller increases the thermal stability of the nanocomposites as investigated by thermogravimetric Analysis (TGA). Glass transition temperature of nanocomposites increases compared with the neat copolymer which was studied by differential scanning calorimetry (DSC). scanning electron microscope (SEM) showed sphere morphology of polymer particles synthesized by miniemulsion polymerization. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) results showed that mixed intercalated and exfoliated morphology is obtained. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Synthesis of aromatic oxazolyl- and carboxyl-functionalized polymers: Atom transfer radical polymerization of styrene initiated by 2-[(4-bromomethyl)phenyl]-4,5-dihydro-4,4-dimethyloxazole

The synthesis of a new compound, 2-[(4-bromomethyl)phenyl]-4,5-dihydro-4,4-dimethyloxazole (1), and its utility in the synthesis of oxazoline-functionalized polystyrene by atom transfer radical polymerization (ATRP) methods are described. Aromatic oxazolyl-functionalized polymers were prepared by the ATRP of styrene, initiated by (1) in the presence of copper(I) bromide/2,2′-bipyridyl catalyst system, to afford the corresponding α-oxazolyl-functionalized polystyrene (2). The polymerization proceeded via a controlled free radical polymerization process to produce the corresponding α-oxazolyl-functionalized polymers with predictable number-average molecular weights, narrow molecular weight distributions in high-initiator efficiency reactions. Post-ATRP chain end modification of α-oxazolyl-functionalized polystyrene (2) to form the corresponding α-carboxyl-functionalized polystyrene (3) was achieved by successive acid-catalyzed hydrolysis and saponification reactions. The polymerization processes were monitored by gas chromatography analyses. The unimolecular-functionalized initiator and functionalized polymers were characterized by thin layer chromatography, spectroscopy, size exclusion chromatography, and nonaqueous titration analysis. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.

Dissecting the role of guanidine copper complexes in atom transfer radical polymerization by density functional theory

Since the development of the living / controlled radical polymerization method ATRP (= atom transfer radical polymerization) in 1995 [1] new catalysts for this reaction have been intensively investigated. This method conquered rapidly numerous fields in chemistry ranging from organic and polymer synthesis to materials science and nanotechnology. Guanidine copper complexes display high activity in ATRP of styrene but the factors imposed on the activator/deactivator equilibrium are multifaceted [2]. Herein we report on new copper complexes with the guanidine ligand 1,3,3-tetramethyl-2-(quinolin-8-yl)guanidine which produce polystyrene with a narrow weight distribution and in high yields. Kinetic studies showed that the polymerization is of living character. Structural characterization leads us to a proposal for the activator and deactivator structures which control the ATRP (Figure ​(Figure1).1). By density functional theory, we were able to dissect the influences on the position of the equilibrium between the Cu(I) and Cu(II) complex (ligand donor strength, halogene bond strength, redox potential, coordinative space) operating the polymerization process. Figure 1 Activator/deactivator equilibrium in ATRP.

ABA2-type triblock copolymer composed of PCL and PSt: synthesis and characterization

ABA2-type (Y-shaped) triblock copolymer made from poly(e-caprolactone) (PCL) and polystyrene were synthesized by the combination of enzymatic ring-opening polymerization (eROP) and atom transfer radical polymerization (ATRP). First, CCl3-terminated PCL were synthesized by eROP of e-caprolactone in the presence of initiator 2,2,2-trichloroethanol and biocatalyst Novozyme 435, followed by the esterification of the resulting PCL with 2,2-dichloro acetyl chloride to obtain trifunctional macroinitiator. The well-defined Y-shaped block copolymer was then synthesized by ATRP of styrene. The systems display characteristics of a living radical polymerization as indicated by linear first-order kinetics, linearly increasing molecular weight with conversion, and low polydispersities. The macromolecular structures and composition were characterized by HNMR, GPC, and FTIR. The thermal properties were characterized by differential scanning calorimetry.

Synthesis, characterization, and property of amphiphilic fluorinated abc-type triblock copolymers

Novel amphiphilic fluorinated ABC-type triblock copolymers composed of hydrophilic poly(ethylene oxide) monomethyl ether (MeOPEO), hydrophobic polystyrene (PSt), and hydrophobic/lipophobic poly(perfluorohexylethyl acrylate) (PFHEA) were synthesized by atom transfer radical polymerization (ATRP) using N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA)/CuBr as a catalyst system. The bromide-terminated diblock copolymers poly(ethylene oxide)-block-polystyrene (MeOPEO-b-PSt-Br) were prepared by the ATRP of styrene initiated with the macroinitiator MeOPEO-Br, which was obtained by the esterification of poly(ethylene oxide) monomethyl ether (MeOPEO) with 2-bromoisobutyryl bromide. A fluorinated block of poly(perfluorohexylethyl acrylate) (PFHEA) was then introduced into the diblock copolymer by a second ATRP process to synthesize a novel ABC-type triblock copolymer, poly(ethylene oxide)-block-polystyrene-block-poly(perfluorohexylethyl acrylate) (MeOPEO-b-PSt-b-PFHEA). These block copolymers were characterized by means of proton nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC). Water contact angle measurements revealed that the polymeric coating of the triblock copolymer (MeOPEO-b-PSt-b-PFHEA) shows more hydrophobic than that of the corresponding diblock copolymer (MeOPEO-b-PSt). Bovine serum albumin (BSA) was used as a model protein to evaluate the protein adsorption property and the triblock copolymer coating posseses excellent protein-resistant character prior to the corresponding diblock copolymer and polydimethylsiloxane. These amphiphilic fluoropolymers can expect to have potential applications for antifouling coatings and antifouling membranes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Synthesis of macrocyclic molecular brushes with amphiphilic block copolymers as side chains

AbstractMacrocyclic molecular brushes c‐PHEMA‐g‐(PS‐b‐PEO) consisting of macrocyclic poly(2‐hydroxylethyl methacrylate) (c‐PHEMA) as backbone and polystyrene‐b‐poly(ethylene oxide) (PS‐b‐PEO) amphiphilic block copolymers as side chains were synthesized by the combination of atom transfer radical polymerization (ATRP), click chemistry, and single‐electron transfer nitroxide radical coupling (SET‐NRC). First, a linear α‐alkyne‐ω‐azido heterodifunctional PHEMA (l‐HCC‐PHEMA‐N3) was prepared by ATRP of HEMA using 3‐(trimethylsilyl)propargyl 2‐bromoisobutyrate as initiator, and then chlorine end groups were transformed to N3 group by nucleophilic substitution reaction in DMF in the presence of an excess of NaN3. The 3‐trimethylsilyl groups could be removed in the presence of tetrabutylammonium fluoride, and the product was cyclized by “click” chemistry in high dilution conditions. The hydroxyl groups on c‐PHEMA were transferred into bromine groups by esterification with 2‐bromoisobutyryl bromide and then initiate the ATRP of styrene. The formed macrocyclic molecular brushes c‐PHEMA‐g‐PS were coupled with the TEMPO‐PEO to afford the target macrocyclic molecular brushes c‐PHEMA‐g‐(PS‐b‐PEO) by SET‐NRC, and the efficiency is as high as 80∼85%. All of the intermediates and final product were characterized with 1H NMR, Fourier transform infrared (FTIR), and gel permeation chromatography in details © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

An exhaustive study of chain-length-dependent and diffusion-controlled free radical and atom-transfer radical polymerization of styrene

A finely tuned-up and high-performance Monte Carlo simulation, which takes diffusion-controlled and chain-length-dependent bimolecular termination reactions into account, is developed to thoroughly simulate and compare free radical (FRP) and atom transfer radical polymerization (ATRP) of styrene. It is found out that the termination rate constant falls and eventually plateaus upon the increase of the chain length of radicals. In addition, average termination rate constant greatly decreases during ATRP; nonetheless, it remains almost unchanged and smaller in FRP. Moreover, there is an accumulation of CuBr2 in the reactor as the ATRP proceeds, while the concentration of CuBr decreases and finally plateaus. Polymer chains are entirely initiated at the beginning of the ATRP, whereas initiation of chains continues throughout the free radical polymerization up to the end of the reaction. Also, the dead polymers are much lower in concentration (only 20%) in ATRP as compared to FRP (about 50%). In addition, a shift (toward higher molecular weight) in the location of the peaks of molecular weight distributions can easily be seen for the ATRP system, whilst the chain length distribution of free-radically generated polymers remains the same throughout the free radical polymerization. The molecular weight distributions narrow as the atom transfer radical polymerization progresses. Finally, the simulation results correspond closely to the experimental data.

Synthesis and self-assembly of miktoarm star copolymers of (polyethylene)2−(polystyrene)2

We report on the synthesis and self-assembly of a novel well-defined miktoarm star copolymer of (polyethylene)2−(polystyrene)2, (PE)2−(PS)2, with two linear crystalline PE segments and two PS segments as the building blocks based on chain shuttling ethylene polymerization (CSEP), click reaction and atom transfer radical polymerization (ATRP). Initially, alkynyl-terminated PE (PE–) was synthesized via the esterification of pentynoic acid with hydroxyl-terminated PE (PE−OH), which was prepared using CSEP with 2,6-bis[1-(2,6-dimethylphenyl) imino ethyl] pyridine iron (II) dichloride/methylaluminoxane/diethyl zinc and subsequent in situ oxidation with oxygen. (PE)2−(OH)2 was then obtained by the click reaction of PE– with diazido and dihydroxyl containing coupling agent. The two hydroxyl groups in (PE)2−(OH)2 were then converted into bromisobutyrate by esterification. At last, the (PE)2−(PS)2 miktoarm star copolymers were synthesized by ATRP of styrene initiated from (PE)2−Br2 macroinitiator. All the intermediates and final products were characterized by 1H NMR and gel permeation chromatography (GPC). The self-assembly behavior was studied by dynamic light scattering (DLS) and atomic force microscopy (AFM). The crystallization of the (PE)2−(PS)2 miktoarm star copolymers was studied by differential scanning calorimetry (DSC).

A novel perfluorocyclobutyl aryl ether-based graft copolymer via 2-methyl-1,4-bistrifluorovinyloxybenzene and styrene

A series of novel perfluorocyclobutyl aryl ether-containing graft copolymers with polystyrene side chains were synthesized by the combination of thermal step-growth [2π+2π] cycloaddition polymerization of aryl bistrifluorovinyl ether monomer and atom transfer radical polymerization (ATRP) of styrene. We first synthesized a new aryl bistrifluorovinyl ether monomer of 2-methyl-1,4-bistrifluorovinyloxybenzene in two steps using commercially available 2-methylhydroquinone as starting material and the corresponding perfluorocyclobutyl aryl ether-based homopolymer with methoxyl end groups was prepared through the homopolymerization of this monomer in diphenyl ether. Next, the pendant methyls of this fluoropolymer were mono-brominated by N-bromosuccinimide and benzoyl peroxide so as to be converted to ATRP initiation groups. The targeted poly(2-methyl-1,4-bistrifluorovinyloxybenzene)-g-polystyrene with relatively narrow molecular weight distributions (Mw/Mn≤1.38) was obtained by the combination of bulk ATRP of styrene at 110°C using CuBr/bpy as catalytic system and the grafting-from strategy. These fluorine-containing graft copolymers show excellent solubility in common organic solvents.

ChemInform Abstract: Synthesis of Block, Graft and Star Polymers from Inorganic Macroinitiators

Recent advances in the synthesis of block, graft and star polymers containing inorganic macromolecular species are described. Anionic copolymerization techniques were used in the formation of diblock copolymers of poly(styreneblock-methylphenylsilylene) and poly(isopreneblock-methylphenylsilylene) by the ring-opening polymerization of 1,2,3,4-tetramethyl-1,2,3,4tetraphenylcyclotetrasilane initiated by living anionic polystyrene and isoprene respectively. Hydrosilation of an attachable initiator onto telechelic vinyl- or hydrosilyl-terminal or -pendant poly(dimethylsiloxane) (PDMS) yielded a PDMS macroinitiator. This macroinitiator was used in atom transfer radical polymerization (ATRP) of styrene and isobornyl acrylate to produce ABA triblock copolymers. As a model for graft copolymers from a polyphosphazene backbone, chemical transformation of hexachlorocyclotriphosphazene resulted in hexafunctional molecules containing either benzyl bromide or bromopropionyl moieties. The initiator 1,1,3,3,5,5-hexakis[4-(2bromopropionyloxymethyl)phenoxy]cyclotriphosphazene was used in the ATRP of styrene to yield a polymer with a narrow, monomodal molecular weight distribution. Chain extension of this star polymer with isobornyl acrylate is also described. # 1998 John Wiley & Sons, Ltd.

Tailor‐Made Soluble Polymer Supports: Synthesis of a Series of ATRP Initiators Containing Labile Wang Linkers

AbstractA series of functional initiators for atom transfer radical polymerization (ATRP) was prepared. These structures contain an ATRP initiating site, a labile p‐alkoxybenzyl ester Wang linker and a functional end‐group (i.e., COOH, N3, OH, CCH, or NHFmoc). These novel initiators can be utilized for synthesizing well‐defined soluble polymer supports. For instance, the azide‐, alcohol‐, alkyne‐, and NHFmoc‐ derivatives were tested as initiators for the bulk ATRP of styrene. SEC, MALDI‐TOF‐MS, and NMR measurements indicated that well‐defined polystyrene samples with defined end‐groups have been synthesized in this process. Moreover, it was demonstrated that the labile Wang linkers could be easily cleaved with a mild trifluoroacetic acid treatment.magnified image

Preparation of Micrometer-Sized, Onionlike Multilayered Block Copolymer Particles by Two-Step AGET ATRP in Aqueous Dispersed Systems: Effect of the Second-Step Polymerization Temperature

The polymerization rate, control/livingness, and particle morphology in seeded activators generated by electron transfer for the atom-transfer radical polymerization of styrene with PiBMA-Br macroinitiator particles were investigated at 70, 90, and 110 degrees C. At 110 degrees C, the polymerization proceeded quickly until 60% conversion was reached, but control/livingness was not observed. This seems to be the reason for the high activation rate and spontaneous initiation of styrene, which significantly increased the radical concentration, resulting in a number of radical terminations. As a result, the block copolymer was not sufficiently formed, leading to a sea-island structure. However, at 70 and 90 degrees C, the polymerizations were almost complete in 14 and 7 h, respectively. Control/livingness was maintained, resulting in PiBMA-b-PS. As a result, onionlike multilayered particles were successfully synthesized. These polymerization behaviors were discussed from the viewpoint of the radical concentration and propagation rate coefficient at various temperatures.

Synthesis of well‐defined rod‐coil block copolymers containing trifluoromethylated poly(phenylene oxide)s by chain‐growth condensation polymerization and atom transfer radical polymerization

AbstractWell‐defined trifluoromethylated poly(phenylene oxide)s were synthesized via nucleophilic aromatic substitution (SNAr) reaction by a chain‐growth polymerization manner. Polymerization of potassium 4‐fluoro‐3‐(trifluoromethyl)phenolate in the presence of an appropriate initiator yielded polymers with molecular weights of ∼4000 and polydispersity indices of <1.2, which were characterized by 1H nuclear magnetic resonance spectroscopy and gel permeation chromatography. Initiating sites for atom transfer radical polymerization (ATRP) were introduced at the either side of chain ends of the poly(phenylene oxide), and used for ATRP of styrene and methyl methacrylate, yielding well‐defined rod‐coil block copolymers. Differential scanning calorimetry study indicated that the well‐defined trifluoromethylated poly(phenylene oxide)s showed high crystallinity and were immiscible with polystyrene. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1049–1057, 2010

Synthesis and Characterization of Telechelic Block Co-polymers by Combination of Atom Transfer Radical Polymerization and Click Chemistry Processes

Hydroxyl functional telechelic block co-polymers, namely α-ω-dihydroxy-poly(styrene-b-tert-butylacrylate) (HO-P(St-b-tBA)-OH) and α-ω-dihydroxy-poly(styrene-b-methyl methacrylate) (HO-P(St-b-MMA)-OH), with well-defined structures and high functionality were synthesized by combination of atom transfer radical polymerization (ATRP) and click chemistry. Hydroxyl and acetylene functional initiators were used in ATRP of styrene (St), and methyl methacrylate (MMA) or t-butylacrylate (tBA) respectively. The bromide terminal group of the hydroxyl functional polystyrene was then converted to an azide group for the subsequent click reaction. Following the first click reaction, these block co-polymers were reacted with propargyl alcohol to incorporate hydroxyl functionality at the other chain-end. The intermediates at various stages and final polymers were characterized by spectral methods.

SYNTHESIS OF ARM-6 POLYSTYRENE BY ATOM TRANSFER RADICAL POLYMERIZATION

A new initiator for atom transfer radical polymerization (ATRP), (Cl-2 HCCOO)(3) -C-6 H-3, (TrDCAP),has been designed and successfully synthesized. ATRP of styrene was carried out by using TrDCAP as hexafunctional initiator and the CuCl/bpy catalyst at 130 degrees C in 30% THF via core-first strategy. The Arm-6 PS-AAP was synthesized by etherealization of Arm-6 PS and 4-(4'-methoxyphenylazomethine) phenol (AAP). The initiator and the architectures of the Arm-6 PS were confirmed by H-1-NMR, FT-IR, UV-Vis and GPC.

ATRP OF STYRENE INITIATED BY 3-CHLORO-2-(CHLOROMETHYL)-1-PROPENE

3-Chloro-2-(chloromethyl)-1-propene(CCMP) was synthesized and used to initiate atom transfer radical polymerization(ATRP) of styrene catalyzed by copper(Ⅰ) chloride/2,2′-bipyridine at 125℃.As a difunctional initiator,CCMP can initiate ATRP of styrene with two living end sites at the same time.The structure of the obtained α,ω-chloropolystyrene was confirmed by()~1H-NMR spectra.The living character of the ATRP process is indicated by narrow molecular weight distributions of the obtained polystyrene(M_w/M_n1.5),a linear(ln([M]_0/[M])) versus time profile and predictable molecular weights proportional to monomer conversion.

Phosphorus ligands for iron(III)‐mediated ATRP of styrene via generation of activators by monomer addition

AbstractStyrene polymerization via generation of activators by monomer addition (GAMA) for atom transfer radical polymerization (ATRP) has been examined extensively with bulk FeX3 and FeX2 at 110 °C in conjunction with various phosphorus‐bearing ligands. It was found that GAMA possesses advantages over normal ATRP. Most importantly, narrower polydispersity index (PDI) values were observed from the styrene polymerizations with Fe(III) over those with Fe(II). Every instance of 2‐(diphenylphosphino)‐N,N′‐dimethyl‐[1,1′‐biphenyl]‐2‐amine and 2‐(diphenylphosphino) pyridine with the Fe(III) system were controlled excellently without addition of any radical initiator or reducing agent additives. Initiator type was found to exert a significant factor to influence on the controllability of polymerization. The initiation of 1‐phenylethyl chloride and methyl‐2‐chloropropionate gave rise to formation of polymers with narrow PDI (1.05–1.20), whereas those from 1‐phenylethyl bromide increased to 1.35. The GAMA of bulk styrene exhibited the best performance in terms of both rate and controllability compared with toluene and anisole. Both formation of block copolymer from the macroinitiator and efficient perturbation of polymerization with 2,2,6,6‐tetramethylpiperidine 1‐oxyl provided firm evidence to support the living and radical characteristics for the GAMA of styrene. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 144–151, 2010

A Facile Strategy for Preparation of α‐Heterobifunctional Polystyrenes with Well‐Defined Molecular Weight

A facile strategy for synthesis of α-heterobifunctional polystyrenes is reported. The novel functional polystyrenes have been successfully synthesized via a combination of atom transfer radical polymerization (ATRP) and chemical modification of end-functional groups. First, ε-caprolactone end-capped polystyrenes with controlled molecular weight and low polydispersity were prepared by ATRP of styrene using α-bromo-ε-caprolactone (αBrCL) as an initiator. Then, removal of the terminal bromine atom was performed with iso-propylbenzene in the presence of CuBr/PMDETA. Finally, ring-opening modifications of the caprolactone group were carried out with amines, n-butanol and H(2) O to produce novel polystyrenes containing two different functional groups at one end.

Synthesis and characterization of cyclohexene oxide functional polystyrene macromonomers by ATRP and their use in photoinitiated cationic polymerization

In this study, a novel well-defined macromonomer of epoxy end-functionalized polystyrene was synthesized by atom transfer radical polymerization (ATRP). The compound 3-cyclohexenylmethyl-2-bromopropanoate was synthesized by the condensation of 3-cyclohexene-1-methanol with 2-bromopropanoyl bromide. Subsequently, the epoxidation of the obtained 3-cyclohexenylmethyl-2-bromopropanoate using 3-chloroperoxybenzoic acid results in a new epoxy functional ATRP initiator. The ATRP of styrene (St) in bulk at 110 °C, by means of this initiator in conjunction with the cuprous complex Cu(I)Br/bipyridine, yields a well-defined macromonomer of polystyrene with an epoxy end group. GPC, IR, and 1H NMR analyses revealed that a low-polydispersity polystyrene with the desired functionality at the end of the chain was obtained. The photoinduced cationic polymerization of this macromonomer yielded graft and block copolymers.

New Iron(II) Complexes for Atom‐Transfer Radical Polymerization: The Ligand Design for Triazacyclononane Results in High Reactivity and Catalyst Performance

AbstractMononuclear cordinatively unsaturated iron(II) complexes having a triazacyclononane ligand were developed as highly efficient and environmentally friendly catalysts for the atom‐transfer radical polymerization (ATRP). These iron catalysts showed high performance in the well‐controlled ATRP of styrene, methacrylates, and acrylates. The high reactivity of these catalysts led to well‐controlled polymerization and block copolymerization even with lower catalyst concentrations.