Butyl Acrylate (butyl + acrylate)

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Selected Abstracts

Temperature-Responsive Water-Soluble Copolymers Based on 2-Hydroxyethyl Acrylate and Butyl Acrylate

Grigoriy A. Mun
Abstract Amphiphilic copolymers have been synthesised by free radical copolymerisation of 2-hydroxyethyl acrylate with butyl acrylate, the reactivity ratios of which indicate practically equal reactivity. The copolymers containing less than 30 mol-% of BA were soluble in water and exhibited a LCST in aqueous solutions. It was found that the interaction between these copolymers and poly(acrylic acid) in aqueous solutions resulted in the formation of interpolymer complexes stabilised by hydrogen bonds and hydrophobic interactions. This interaction was significantly affected by solution pH and led to modification of the temperature-responsive behaviour of the copolymers. [source]

Chain Transfer to Polymer and Branching in Controlled Radical Polymerizations of n -Butyl Acrylate

Nasir M. Ahmad
Abstract Chain transfer to polymer (CTP) in conventional free-radical polymerizations (FRPs) and controlled radical polymerizations (ATRP, RAFT and NMP) of n -butyl acrylate (BA) has been investigated using 13C NMR measurements of branching in the poly(n -butyl acrylate) produced. The mol-% branches are reduced significantly in the controlled radical polymerizations as compared to conventional FRPs. Several possible explanations for this observation are discussed critically and all except one refuted. The observations are explained in terms of differences in the concentration of highly reactive short-chain radicals which can be expected to undergo both intra- and inter-molecular CTP at much higher rates than long-chain radicals. In conventional FRP, the distribution of radical concentrations is broad and there always is present a significant proportion of short-chain radicals, whereas in controlled radical polymerizations, the distribution is narrow with only a small proportion of short-chain radicals which diminishes as the living chains grow. Hence, irrespective of the type of control, controlled radical polymerizations give rise to lower levels of branching, when performed under otherwise similar conditions to conventional FRP. Similar observations are expected for other acrylates and monomers that undergo chain transfer to polymer during radical polymerization. [source]

ChemInform Abstract: Palladium-Catalyzed Arylation of Butyl Acrylate and Acrylamide with Aryl Iodides in Water.

CHEMINFORM, Issue 28 2002
Hong Zhao
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Copolymerization of Divinylsilyl-11-silicotungstic Acid with Butyl Acrylate and Hexanediol Diacrylate: Synthesis of a Highly Proton-Conductive Membrane for Fuel-Cell Applications

Abstract Highly conducive to high conductivity: Polyoxometalates were incorporated in the backbone of a hydrocarbon polymer to produce proton-conducting films. These first-generation materials contain large, dispersed clusters of polyoxometalates. Although the morphology of these films is not yet optimal, they already demonstrate practical proton conductivities and proton diffusion within the clusters appears to be very high. [source]

Terpolymerization monitoring with ATR-FTIR spectroscopy

Hong Hua
Abstract Butyl acrylate, methyl methacrylate, and vinyl acetate solution and emulsion terpolymerizations were conducted. Attenuated total relflection-Fourier transform infrared spectroscopy equipped with conduit and diamond-composite sensor technology was used to monitor solution terpolymerizations off-line and emulsion terpolymerizations in-line. Monomer conversion and terpolymer composition changes as a function of time were calculated by monitoring the peak height of characteristic absorbances of each monomer. Results obtained from the ReactIRÔ 1000 reaction-analysis system agreed well with those determined by traditional gravimetry and 1H NMR spectroscopy. For the solution terpolymerizations, improved models developed previously to incorporate solvent effects on solution polymerizations of butyl acrylate and vinyl acetate monomers were applied to predict monomer conversion, copolymer composition, and molecular weight averages. Comparisons between experimental data and model predictions are presented. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1860,1876, 2001 [source]

Using the Aggregation of Latex Polymers in the Fabrication of Reproducible Enzyme Electrodes

Wibowo Rahmat
Abstract An enzyme electrode for glucose is described as a model system to demonstrate a fabrication method using latex aggregation and entrapment of enzyme. Electrosterically-stabilized latex particles synthesized by emulsion polymerization in batch from acrylic acid, methyl methacrylate and butyl acrylate, and glucose oxidase were coagulated together at pH,5.5 with ethanol. A platinum disk electrode dipped in the solution becomes coated with latex/enzyme. The relative thickness of the film and relative amount of enzyme may be controlled by the time the electrode is in contact with the solution. The enzyme was then immobilized by covalent attachment of amine groups to carboxylic moieties in the polymer using 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide hydrochloride and N -hydroxysuccinimide. Five minutes contact with the latex/enzyme solution and subsequent amide coupling, gave electrodes with a reproducibility of 5.7% RSD, a wide dynamic range (0,100,mM) and good storage properties. [source]

Synthesis and Use of New Substituted 1,3,5-Hexatrienes in Studying Thermally Induced 6, -Electrocyclizations,

Hans Wolf Sünnemann
Abstract An acyclic, two heterocyclic, and two bicyclic alkenylstannanes, 3, 4a, 4b, 8 and 11, respectively, were synthesized in yields ranging from 43 to 97,%, and each was subjected to a sequence of Stille and Heck couplings with 2-bromocyclohexenyl triflate (13) and alkyl (tert -butyl and methyl) acrylate to furnish seven new 1,3,5-hexatrienes 19, 20, 21, 22 - tBu, 22 -Me, 23 and 43, respectively, in 58,84,% yields. For the alkenylstannanes 4a,b, 8 and 11, customized combinations of catalysts had to be used. The Stille,Heck sequence involving 13, 3 and tert -butyl acrylate could be performed in a one-pot mode and proceeded in 75,% yield. The hexatrienes were heated in decalin solutions so as to effect 6,-electrocyclization. Temperatures and reaction times were optimized individually. The hexatrienes 29, 31 and 36 gave the bi- and tricyclic cyclohexadienes 28, 30 and 34, incorporating allylic alcohol and allyl ether termini, by 6,-electrocyclization and subsequent [1,5]-hydrogen shift, as single products in good yields (85,93,%). In contrast, the hexatrienes 19, 20, 21 and 39 furnished mixtures of the initial electrocyclization products 26, 32, 37 and 40 as well as the products of a subsequent [1,5]-hydrogen shift 27, 33, 38 and 41, respectively. The tricyclic hexatrienes 22 - tBu, 22 -Me and 23 bearing alkyl (tert -butyl, methyl) acrylate termini also selectively gave the tetracyclic dienes 48 - tBu, 48 -Me and 50 in 71,77,% yields by electrocyclizations and subsequent hydrogen shifts.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Reactive Imprint Lithography: Combined Topographical Patterning and Chemical Surface Functionalization of Polystyrene- block -poly(tert -butyl acrylate) Films

Joost Duvigneau
Abstract Here, reactive imprint lithography (RIL) is introduced as a new, one-step lithographic tool for the fabrication of large-area topographically patterned, chemically activated polymer platforms. Films of polystyrene- block -poly(tert -butyl acrylate) (PS- b -PtBA) are imprinted with PDMS master stamps at temperatures above the corresponding glass transition and chemical deprotection temperatures to yield structured films with exposed carboxylic acid and anhydride groups. Faithful pattern transfer is confirmed by AFM analyses. Transmission-mode FTIR spectra shows a conversion of over 95% of the tert -butyl ester groups after RIL at 230,°C for 5 minutes and a significantly reduced conversion to anhydride compared to thermolysis of neat films with free surfaces in air or nitrogen. An enrichment of the surface layer in PS is detected by angle-resolved X-ray photoelectron spectroscopy (XPS). In order to demonstrate application potentials of the activated platforms, a 7,nm,±,1,nm thick NH2 -terminated PEG layer (grafting density of 0.9 chains nm,2) is covalently grafted to RIL-activated substrates. This layer reduces the non-specific adsorption (NSA) of bovine serum albumin by 95% to a residual mass coverage of 9.1,±,2.9,ng cm,2. As shown by these examples, RIL comprises an attractive complementary approach to produce bio-reactive polymer surfaces with topographic patterns in a one-step process. [source]

Dual-Tone Patterned Mesoporous Silicate Films Templated From Chemically Amplified Block Copolymers

Sivakumar Nagarajan
Abstract Directly patterned mesoporous silicate films are prepared using positive- and negative-tone strategies by performing phase selective silica condensation within lithographically exposed poly(styrene- b - tert -butyl acrylate) (PS- b -PtbA) templates containing photoacid generators. The use of supercritical fluid as a process medium enables rapid diffusion of the silicate precursor within the prepatterned block copolymer template film without disrupting its morphology. Template exposure through the mask triggers area selective generation of acid, which in turn both deprotects the poly(tert -butyl acrylate) block to yield a poly(acrylic acid) block and provides a catalyst for silica precursor condensation yielding pattern formation at the device level. Because the acid generated in the UV exposed field preferentially segregates into hydrophilic poly(acrylic acid) domains of the phase segregated, deprotected block copolymer, precursor condensation is simultaneously controlled at nanoscopic length scales via templating by the underlying block copolymer morphology. The ability of PS- b -PtbA to undergo chemical transformation in two stages, deprotection followed by crosslinking, enables precise replications of the photomask in positive and negative tones. Detemplating via calcination yields patterned mesoporous silicate films without etching. Template formulations are optimized using infrared spectroscopic studies and the silicate films are characterized using electron microscopy and scanning force microscopy. [source]

Waterborne, Nanocomposite Pressure-Sensitive Adhesives with High Tack Energy, Optical Transparency, and Electrical Conductivity,

T. Wang
Transparent and conductive pressure-sensitive adhesives are cast from aqueous colloidal dispersions of poly(butyl acrylate) (P(BuA)) and functionalized carbon nanotubes (CNTs). At the percolation threshold for network formation (at only 0.3,wt,% functionalized CNT), the nanotubes remarkably double the amount of strain at adhesive failure and increase the adhesion energy by 85,% (see figure). The tack properties are explained by current models of adhesive debonding. [source]

Comparison of polyamide 66,organoclay binary and ternary nanocomposites

Miray Mert
Abstract Polyamide 66,Lotader® 2210 blends (95/5 w/w), polyamide 66,Cloisite® 15A binary nanocomposites (98/2 w/w), and polyamide 66,Lotader® 2210,Cloisite® 15A ternary nanocomposites (93/5/2 w/w) were prepared by twin-screw extrusion, and the changes in mechanical properties, morphology, and flow properties of the materials prepared by different mixing sequences were investigated in this study. Lotader® 2210, which is a random terpolymer of ethylene, butyl acrylate, and maleic anhydride, was used as the impact modifier for polyamide 66 blends as well as polyamide 66 based nanocomposites. The best dispersion level, highest mechanical properties, highest viscosity values, and smallest elastomeric domain sizes were obtained for the mixing sequence in which all the components forming the ternary nanocomposites were compounded simultaneously. Incorporation sequence of either the organoclay or the impact modifier into the polymeric matrix was varied in the other mixing sequences, and this resulted in poorer distribution of the organoclay platelets and elastomeric domains in the matrix owing to insufficient shear intensity applied on the components in a single extrusion step. Toughness values of the ternary nanocomposites were improved compared with the binary nanocomposites upon addition of the impact modifier into polymer,organoclay combination. It was concluded that the compounding sequence of the components plays a significant role in the dispersion of organoclay and the properties of the nanocomposites, because it directly affects the interaction between the different phases. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:155,164, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20158 [source]

Free radical graft copolymerization of poly(n -butyl methacrylate) and poly(butyl acrylate) onto chlorinated rubber: Characterization and mechanical properties,

Shanaz Ahmed
Abstract Graft copolymerization of n -butyl methacrylate and butyl acrylate onto chlorinated rubber was carried out in solution medium (xylene) using benzoyl peroxide as initiator. The chlorinated rubber-g-(n -butyl methacrylate- co -butyl acrylate) (CR-g-nBMA- co -BA) was isolated from the copolymerization mixture by extracting with isopropyl ether. Infrared (FT-IR) spectra, proton nuclear magnetic resonance (1H NMR) and thermogravimetric analysis of the graft copolymer showed the occurrence of grafting. Percent grafting and grafting efficiency calculated under different experimental conditions are discussed. The mechanical properties of the grafted CR films were studied under different strain rates. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 103,110, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20003 [source]

Well-defined diblock and triblock copolymers for KrF lithography

Ting-Yu Lee
Abstract One of the major components of a photoresist formulation is polymer resin. Well-defined diblock and random copolymer of tert -butyl acrylate (tBA) and 4-acetoxystyrene (StyOAc), as well as triblock and random tertpolymer of tBA, StyOAc, and Sty were prepared by reversible addition fragmentation chain transfer polymerization (RAFT) process. The polymers all possess Mw about ten thousand and PDI less than 1.23. After hydrolysis under basic condition, the hydroxystyrene (StyOH) analogs are obtained and then are formulated as photoresist. Lithographic evaluation under KrF excimer laser shows that random copolymer based photoresist exhibits better S/L patterns according to SEM images. However, the lithographic performance of the terpolymer based resists is similar. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Mechanical properties and flammability of polycarbonate alloys containing nanosize additives

Zhiyi Zhang
Abstract Different organic,inorganic composite particles [montmorillonite/poly(butyl acrylate) (PBA)/poly(methyl methacrylate) (PMMA), SiO2/PBA/PMMA, and CaCO3/PBA/PMMA] were synthesized by emulsion polymerization. Furthermore, polycarbonate (PC) alloys were prepared via the doping of these composite particles into PC with a twin-screw extruder. The structure, mechanical properties, and flammability of the PC alloys were studied in detail. Although the tensile modulus of PC decreased a little, the flexibility and impact resistance were improved by the addition of these composite particles. This result was attributed to the fact that the composite particles were well dispersed in the PC matrix, with a cocontinuous phase formed between the particles and PC. In addition, the combustion behavior of the PC alloys, compared with that of the pure PC, resulted from a ceramic-like char that formed on the surface of the PC alloys during burning. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

Emulsion polymerization of styrene with amphiphilic random copolymer as surfactant: Predominant droplet nucleation

Li Liu
Abstract Amphiphilic random copolymer consisting of monomeric units of poly (butyl acrylate) and poly (maleic acid salt) was synthesized and characterized. The emulsion polymerization kinetics of styrene stabilized by this copolymer was investigated. The influencing factors, including polymeric surfactant concentration, initiator concentration and polymerization temperature, were systematically studied. The kinetic data show that the polymerization rate (RP) increased with the increase of the polymeric surfactant concentration ([S]) and polymerization temperature (T). At the higher [S], droplets nucleation and micelle nucleation coexisted in the polymerization system; at the lower [S], only the droplets nucleation process existed. The polymerization did not follow Smith-Ewart Case II kinetics. Dynamic light scatter and transmission electron microscope were utilized to measure the sizes and shapes of the particles, respectively. It would be speculated that a kind of large heterogeneous particles with multiple-active-sites was formed in the polymerization system. The increasing of RP with increasing initiator concentration ([KPS]) was rapid at a medium [KPS], but the slowly increasing was observed at a lower or higher [KPS]. It was attributed to the barrier effect of the polymeric surfactant around the monomer droplets. The polymerization activation energy was 60.29 kJ/mol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

Effect of acrylic core,shell rubber particles on the particulate flow and toughening of PVC

M. R. Moghbeli
Abstract Different types of acrylic core,shell rubber particles with a poly(butyl acrylate) (PBA) core and a grafted poly(methyl methacrylate) (PMMA) shell were synthesized. The average size of acrylic core,shell latex particles ranged from 100 to 170 nm in diameter, having the core gel content in the range of 35,80%. The melt blending behavior of the poly(vinyl chloride) (PVC) and the acrylic core,shell rubber materials having different average particle sizes and gel contents was investigated in a batch mixing process. Although the torque curves showed that the particulate flow of the PVC in the blends was dominant, some differences were observed when the size and gel content of the particles varied. This behavior can be attributed to differences in the plasticizing effect and dispersion state of various types of core,shell rubber particles, which can vary the gelatin process of the PVC in the mixing tool. On the other hand, the highest toughening efficiency was obtained using core,shell rubber particles with the smallest particle size (i.e., 100 nm). The results showed that increasing the gel content of the core,shell impact modifiers with the same particle size improved the particle dispersion state in the PVC matrix. The toughening efficiency decreased for the blends containing 100 and 170 nm rubber particles as the gel content increased. Nevertheless, unexpected behavior was observed for the blends containing 140 nm rubber particles. It was found that a high level of toughness could be achieved if the acrylic core,shell rubber particles as small as 100 nm had a lower gel content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

NMR analysis of butyl acrylate/methylmethacrylate/,-methyl styrene terpolymers

Neil T. McManus
Abstract Composition analysis for butyl acrylate (BA)/ methyl methacrylate (MMA)/,-methyl styrene terpolymers was carried out by NMR spectroscopy methods. 1H-NMR was used primarily for this analysis, but because the method did not provide independent measurements for the BA and MMA fractions, the terpolymer composition analysis was open to higher than normal levels of uncertainty. Supplementary analyses were made with quantitative 13C-NMR methods to confirm the results from 1H-NMR (quantitative 13C-NMR was used to provide corroboration of selected composition analyses). To confirm spectral assignments in the 1H- and 13C-NMR spectra, heteronuclear multiple quantum coherence and J Modulated Spin Echo (JMOD) pulse sequences were used. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2093,2098, 2007 [source]

Amphiphilic polymer conetworks prepared by controlled radical polymerization using a nitroxide cross-linker

Weijie Zhao
Abstract Tandem atom transfer radical polymerization (ATRP) and nitroxide-mediated radical polymerization (NMRP) were used to synthesize a polystyrene- co -poly(acrylic acid) (poly(St- co -AA)) network, in which the two components were interconnected by covalent bond. First, a specific cross-linker, 1,4-bis(1,-(4,-acryloyloxy-2,,2,,6,,6,-tetramethylpiperidinyloxy)ethyl)benzene (di -AET), a bifunctional alkoxyamine possessing two acrylate groups, was copolymerized with tert -butyl acrylate through ATRP to prepare a precursor gel. The gel was then used to initiate the NMRP of styrene to prepare poly(St- co -(t -BA)) conetwork, in which the cross-linkages are composed of polystyrene segments. Finally, the poly(St- co -(t -BA)) conetwork was hydrolyzed to produce amphiphilic poly(St- co -AA) conetwork. The resulting gels show swelling ability in both organic solvent and water, which is characteristic of amphiphilic conetworks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4141,4149, 2010 [source]

Investigation of thiol-ene addition reaction on poly(isoprene) under UV irradiation: Synthesis of graft copolymers with "V"-shaped side chains

Guowei Wang
Abstract Poly(isoprene) (PI) with pendant functional groups was successfully synthesized by thiol-ene addition reaction under 365 nm UV irradiation, and the functionalized PI was further modified and used to prepare graft copolymers with "V"-shaped side chains. First, the pendant SCH2CH(OH)CH2OH groups were introduced to PI by thiol-ene addition reaction between 1-thioglycerol and double bonds, and the results showed that the addition reaction carried out only on double bonds of 1,2-addition isoprene units. After the esterification of hydroxyl groups by 2-bromoisobutyryl bromide, the forming macroinitiator was used to initiate the atom transfer radical polymerization (ATRP) of styrene (St) and tert -butyl acrylate (tBA), and the graft copolymers PI- g -PS2 and PI- g -PtBA2 or PI- g -PAA2 (by hydrolysis of PI- g -PtBA2) were obtained, respectively. It was confirmed that the graft density of side chains on PI main chains could be easily controlled by variation of the contents of modified 1,2-addition isoprene units on PI. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3797,3806, 2010 [source]

Synthesis and self-assembly of well-defined cyclodextrin-centered amphiphilic A14B7 multimiktoarm star copolymers based on poly(,-caprolactone) and poly(acrylic acid)

Peng-Fei Gou
Abstract Novel amphiphilic A14B7 multimiktoarm star copolymers composed of 14 poly(,-caprolactone) (PCL) arms and 7 poly(acrylic acid) (PAA) arms with ,-cyclodextrin (,-CD) as core moiety were synthesized by the combination of controlled ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP). 14-Arm star PCL homopolymers (CDSi-SPCL) were first synthesized by the CROP of CL using per-6-(tert -butyldimethylsilyl)-,-CD as the multifunctional initiator in the presence of Sn(Oct)2 at 125 °C. Subsequently, the hydroxyl end groups of CDSi-SPCL were blocked by acetyl chloride. After desilylation of the tert -butyldimethylsilyl ether groups from the ,-CD core, 7 ATRP initiating sites were introduced by treating with 2-bromoisobutyryl bromide, which further initiated ATRP of tert -butyl acrylate (tBA) to prepare well-defined A14B7 multimiktoarm star copolymers [CDS(PCL-PtBA)]. Their molecular structures and physical properties were in detail characterized by 1H NMR, SEC-MALLS, and DSC. The selective hydrolysis of tert -butyl ester groups of the PtBA block gave the amphiphilic A14B7 multimiktoarm star copolymers [CDS(PCL-PAA)]. These amphiphilic copolymers could self-assemble into multimorphological aggregates in aqueous solution, which were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2961,2974, 2010 [source]

Synthesis of comb polymers via grafting-onto macromolecules bearing pendant diene groups via the hetero-Diels-Alder-RAFT click concept

Antoine Bousquet
Abstract Comb polymers were synthesized by the "grafting-onto" method via a combination of Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization and the hetero-Diels-Alder (HDA) cycloaddition. The HDA reactive monomer trans, trans-hexa-2,4-dienylacrylate (ttHA) was copolymerized with styrene via the RAFT process. Crosslinking was minimized by decreasing the monomer concentration,whilst keeping monomer to polymer conversions low,resulting in reactive backbones with on average one reactive pendant diene groups for 10 styrene units. The HDA cycloaddition was performed between the diene functions of the copolymer and a poly(n -butyl acrylate) (PnBA) prepared via RAFT polymerization with pyridin-2-yldithioformate, which can act as a dienophile. The coupling reactions were performed within 24 h at 50 °C and the grafting yield varies from 75% to 100%, depending on the number average molecular weight of the PnBA (3500 g mol,1 < Mn < 13,000 g mol,1) grafted chain and the reaction stoichiometry. The molecular weights of the grafted block copolymers range from 19,000 g mol,1 to 58,000 g mol,1 with polydispersities close to 1.25. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1773,1781, 2010 [source]

Well-defined amphiphilic graft copolymer consisting of hydrophilic poly(acrylic acid) backbone and hydrophobic poly(vinyl acetate) side chains

Yaogong Li
Abstract A series of well-defined amphiphilic graft copolymers containing hydrophilic poly(acrylic acid) (PAA) backbone and hydrophobic poly(vinyl acetate) (PVAc) side chains were synthesized via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization followed by selective hydrolysis of poly(tert -butyl acrylate) backbone. A new Br-containing acrylate monomer, tert -butyl 2-((2-bromopropanoyloxy)methyl) acrylate, was first prepared, which can be polymerized via RAFT in a controlled way to obtain a well-defined homopolymer with narrow molecular weight distribution (Mw/Mn = 1.08). This homopolymer was transformed into xanthate-functionalized macromolecular chain transfer agent by reacting with o -ethyl xanthic acid potassium salt. Grafting-from strategy was employed to synthesize PtBA- g -PVAc well-defined graft copolymers with narrow molecular weight distributions (Mw/Mn < 1.40) via RAFT of vinyl acetate using macromolecular chain transfer agent. The final PAA- g -PVAc amphiphilic graft copolymers were obtained by selective acidic hydrolysis of PtBA backbone in acidic environment without affecting the side chains. The critical micelle concentrations in aqueous media were determined by fluorescence probe technique. The micelle morphologies were found to be spheres. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6032,6043, 2009 [source]

Synthesis of PMMA- b -PBA block copolymer in homogeneous and miniemulsion systems by DPE controlled radical polymerization

Ying-Da Luo
Abstract In this research, poly(methyl methacrylate)- b -poly(butyl acrylate) (PMMA- b -PBA) block copolymers were prepared by 1,1-diphenylethene (DPE) controlled radical polymerization in homogeneous and miniemulsion systems. First, monomer methyl methacrylate (MMA), initiator 2,2,-azobisisobutyronitrile (AIBN) and a control agent DPE were bulk polymerized to form the DPE-containing PMMA macroinitiator. Then the DPE-containing PMMA was heated in the presence of a second monomer BA, the block copolymer was synthesized successfully. The effects of solvent and polymerization methods (homogeneous polymerization or miniemulsion polymerization) on the reaction rate, controlled living character, molecular weight (Mn) and molecular weight distribution (PDI) of polymers throughout the polymerization were studied and discussed. The results showed that, increasing the amounts of solvent reduced the reaction rate and viscosity of the polymerization system. It allowed more activation,deactivation cycles to occur at a given conversion thus better controlled living character and narrower molecular weight distribution of polymers were demonstrated throughout the polymerization. Furthermore, the polymerization carried out in miniemulsion system exhibited higher reaction rate and better controlled living character than those in homogeneous system. It was attributed to the compartmentalization of growing radicals and the enhanced deactivation reaction of DPE controlled radical polymerization in miniemulsified droplets. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4435,4445, 2009 [source]

Preparation of H-shaped ABCAB terpolymers by atom transfer radical coupling

Xiaolan Luo
Abstract H-shaped ABCAB terpolymers composed of polystyrene (PS) (A), poly(ethylene oxide) (PEO) (B), and poly(tert -butyl acrylate) (PtBA) (C) were prepared by atom transfer radical coupling reaction using ABC star terpolymers as precursors, CuBr and N,N,N,,N,,N,-pentamethyldiethylenetriamine (PMDETA) as catalysts, and nanosize copper as the reducing agent. The synthesis of 3-miktoarm star terpolymer PS-PEO-(PtBA-Br) involved following steps: (1) the preparation of PS with an active and an ethoxyethyl-ptotected hydroxyl group at the same end; (2) the preparation of diblock copolymer PS- b -PEO with ethoxyethyl-protected group at the junction point through the ring-opening polymerization (ROP) of EO; (3) after de-protection of ethoxyethyl group and further modification of hydroxyl group, tBA was polymerized by atom transfer radical polymerization using PS- b -PEO with 2-bromoisobutyryl functional group as macroinitiator. The H-shaped terpolymer could be successfully formed by atom transfer radical coupling reaction in the presence of small quantity of styrene, CuBr/PMDETA, and Cu at 90 °C. The copolymers were characterized by SEC, 1H NMR, and FTIR in detail. The optimized coupling temperature is 90 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 59,68, 2009 [source]

Poly(ethylene glycol)-based amphiphilic model conetworks: Synthesis by RAFT polymerization and characterization

Mariliz Achilleos
Abstract Poly(ethylene glycol) (PEG)-containing quasi-model amphiphilic polymer conetworks (APCNs) were prepared by reversible addition fragmentation chain transfer (RAFT) polymerization using ,,,-bis(2-cyanoprop-2-yl dithiobenzoate)-PEG as a bifunctional RAFT macrochain transfer agent (macro-CTA) and stepwise additions of a hydrophobic monomer and a crosslinker (crosslinker: macro-CTA = 10:1, reaction time 24 h). Three different types of monomers, methyl methacrylate (MMA), n -butyl acrylate and styrene, were employed as the hydrophobic monomers, whereas ethylene glycol dimethacrylate, ethylene glycol diacrylate and 1,4-divinylbenzene served as the respective crosslinkers. PEG homopolymer hydrophilic quasi-model networks were also prepared by RAFT-polymerizing the three crosslinkers directly onto the two active ends of the PEG-based macro-CTA. From the three ABA triblock copolymers prepared, the MMA-containing one was obtained at the highest polymerization yields. The crosslinking yields of the three ABA triblock copolymers with the corresponding crosslinkers were higher than those of the PEG-based macro-CTA with the same crosslinkers. The degrees of swelling (DSs) of all conetworks were measured in water and in tetrahydrofuran (THF). The DSs of the APCNs in THF were higher than those in water, whereas the reverse was true for the DSs of the hydrophilic homopolymer networks. Finally, the aqueous DSs of the APCNs were lower than those of the corresponding hydrophilic homopolymer networks. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7556,7565, 2008 [source]

One-pot synthesis of heterograft copolymers via "graft onto" by atom transfer nitroxide radical coupling chemistry

Qiang Fu
Abstract Heterograft copolymers poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl- co - ethylene oxide)- graft -polystyrene and poly(tert -butyl acrylate) (poly (GTEMPO- co -EO)- g -PS/PtBA) were synthesized in one-pot by atom transfer nitroxide radical coupling (ATNRC) reaction via "graft onto." The main chain was prepared by the anionic ring-opening copolymerization of ethylene oxide (EO) and 4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (GTEMPO) first, then the polystyrene and poly (tert -butyl acrylate) with bromine end (PS-Br, PtBA-Br) were prepared by atom transfer radical polymerization (ATRP). When three of them were mixed each other in the presence of CuBr/N,N,N,,N,,N,-pentamethyldiethylenetriamine (PMDETA) at 90 °C, the formed secondary carbon radicals at the PS and PtBA chain ends were quickly trapped by nitroxide radicals on poly(GTEMPO- co -EO). The heterograft copolymers were well defined by 1H NMR, size exclusion chromatography, fourier transform infrared, and differential scanning calorimetry in detail. It was found that the density of GTEMPO groups on main chain poly(GTEMPO- co -EO), the molecular weights of PS/PtBA side chains, and the structure of macroradicals can exert the great effects on the graft efficiency. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6770,6779, 2008 [source]

Dendrimer-like miktoarm star terpolymers: A3 -(B-C)3 via click reaction strategy

Ozcan Altintas
Abstract Two samples of dendrimer-like miktoarm star terpolymers: (poly(tert -butyl acrylate))3 -(polystyrene-poly(,-caprolactone))3 (PtBA)3 -(PS-PCL)3, and (PS)3 -(PtBA-poly(ethylene glycol)3 were prepared using efficient Cu catalyzed Huisgen cycloaddition (click reaction). As a first step, azido-terminated 3-arm star polymers PtBA and PS as core (A) were synthesized by atom transfer radical polymerization (ATRP) of tBA and St, respectively, followed by the conversion of bromide end group to azide. Secondly, PS-PCL and PtBA-PEG block copolymers with alkyne group at the junction as peripheral arms (B-C) were obtained via multiple living polymerization mechanisms such as nitroxide mediated radical polymerization (NMP) of St, ring opening polymerization (ROP) of ,-CL, ATRP of tBA. Thus obtained core and peripheral arms were linked via click reaction to give target (A)3 -(B-C)3 dendrimer-like miktoarm star terpolymers. (PtBA)3 -(PS-PCL)3 and (PS)3 -(PEG-PtBA)3 have been characterized by GPC, DSC, AFM, and SAXS measurements. (PtBA)3 -(PS-PCL)3 did not show any self-organization with annealing due to the miscibility of the peripheral arm segments. In contrast, the micro-phase separation of the peripheral arm segments in (PS)3 -(PtBA-PEG)3 resulted in self-organized phase-separated morphology with a long period of , 13 nm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5916,5928, 2008 [source]

Cyclometalated 2-phenylpyridine complex [RuII(o -C6H4 -py)(MeCN)4]PF6 as a tunable catalyst for living radical polymerization

F. Diaz Camacho
Abstract The cyclometalated complex [RuII(o -C6H4 -py)(MeCN)4]PF6 (1) with a ,-RuC bond and four substitutionally labile acetonitrile ligands mediates radical polymerization of different vinyl monomers, viz. n -butyl acrylate, methyl methacrylate, and styrene, initiated by three alkyl bromides: ethyl 2-bromoisobutyrate, methyl 2-bromopropionate, and 1-phenylethyl bromide. The polymerization requires the presence of Al(OiPr)3 and occurs uncontrollably as a conventional radical process. The variation of the molar ratio of the components of the reaction mixture, such as initiator, Al(OiPr)3 and catalyst, affected the polymerization rates and the molecular weights but did not improve the control. A certain level of control has been achieved by adding 0.5 eq of SnCl2 as a reducing agent. Tin(II) chloride decreased the rate of polymerization and simultaneously the molecular weights became conversion-dependent and the polydispersities were also narrowed. Remarkably, the level of control was radically improved in the presence of excess of the poorly soluble catalyst (1), when the added amount of (1) was not soluble any more, i.e., under heterogeneous conditions, the system became adjustable and the living polymerization of all three monomers was finally achieved. Possible mechanisms of the (1)-catalyzed polymerization are discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4193,4204, 2008 [source]

Functionalization of carbon nanofibers (CNFs) through atom transfer radical polymerization for the preparation of poly(tert -butyl acrylate)/CNF materials: Spectroscopic, thermal, morphological, and physical characterizations

Marcos Ghislandi
Abstract Vapor-grown carbon nanofibers (CNFs) were oxidized and functionalized for atom transfer radical polymerization (ATRP) of tert -butyl acrylate (t -BA) from the surface of the CNFs. The materials were characterized by solubility tests, Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy. The FTIR and electron microscopy results suggest that ATRP process was successfully used to graft poly(tert -butyl acrylate) (poly(t -BA)) chains from the surface of the fibers. Raman results strongly indicate the partial degradation of the graphitic layer of CNFs because of the chemical treatments. TGA results suggest that the presence of poly(t -BA) leads to a decrease of the initial degradation temperature of the fibers. XRD and electron microscopy results indicate that the microstructure of fibers was not destroyed because of the oxidation and functionalization processes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3326,3335, 2008 [source]

Block copolymer preparation by atom transfer radical polymerization under emulsion conditions using a nanoprecipitation technique

Delphine Chan-Seng
Abstract Living-radical polymerization of acrylates were performed under emulsion atom transfer radical polymerization (ATRP) conditions using latexes prepared by a nanoprecipitation technique previously employed and optimized for the polymerization of styrene. A macroinitiator of poly(n -butyl acrylate) prepared under bulk ATRP was dissolved in acetone and precipitated in an aqueous solution of Brij 98 to preform latex particles, which were then swollen with monomer and heated. Various monomers (i.e. n -butyl acrylate, styrene, and tert -butyl acrylate) were used to swell the particles to prepare homo- and block copolymers from the poly(n -butyl acrylate) macroinitiator. Under these conditions latexes with a relatively good colloidal stability were obtained. Furthermore, amphiphilic block copolymers were prepared by hydrolysis of the tert -butyl groups and the resulting block copolymers were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The bulk morphologies of the polystyrene- b -poly(n -butyl acrylate) and poly(n -butyl acrylate)- b -poly(acrylic acid) copolymers were investigated by atomic force microscopy (AFM) and small angle X-ray scattering (SAXS). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 625,635, 2008 [source]