Emulsion copolymerization of vinyl acetate and butyl acrylate in the presence of fluorescent dyes

This article describes our first experiments for preparing dye‐labeled latex particles by the emulsion copolymerization of a 4/1 (w/w) mixture of vinyl acetate‐butylacrylate (VAc‐BA). We discuss the synthesis of acrylate derivatives of phenanthrene, anthracene, and pyrene [9‐acryloxymethyl phenanthrene ( 7 ), 9‐acryloxymethyl‐10‐methyl anthracene ( 8 ), and 1‐acryloxymethyl pyrene ( 10 )] and an allyl ether derivative of anthracene [9‐allyoxymethyl‐10‐methyl anthracene ( 9 )]. Although the phenanthrene derivative 7 gave latex particles with high monomer conversion and good dye incorporation, the pyrene acrylate and both anthracene comonomers strongly inhibited the free‐radical reaction. To assist our search for a dye that would serve as a useful energy acceptor for phenanthrene and without suppressing VAc‐BA polymerization, we also examined batch emulsion polymerization in the presence of a variety of dye derivatives—substituted anthracenes, acridines, a coumarin, and two benzophenone derivatives. All of the anthracene derivatives, as well as acridine, strongly inhibited monomer polymerization. The coumarin dye 7‐hydroxy‐4‐methyl coumarin ( 22 ) that had only limited solubility allowed more than 90% monomer conversion. Most promising were 2‐hydroxy‐5‐methyl benzophenone ( 23 ) and 4‐N,N‐dimethylamino benzophenone ( 24 ) that at 1 mol % in the monomer mixture permitted virtually quantitative monomer conversion to latex. 4′‐Dimethylamino‐2‐acryloxy‐5‐methyl benzophenone ( 25 ) copolymerized well with the VAc‐BA mixture, yielding latex particles in high yield and with a narrow size distribution. These dyes appear to be useful acceptor dyes for energy‐transfer experiments with phenanthrene. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1594–1607, 2002     

Synthesis and morphology of Fe3O4/polystyrene/poly(isopropylacrylamide‐co‐methyl acrylate acid) magnetic composite latex – 2,2′‐azobis (2‐methylpropionamidine) dihydrochloride as initiator

In this work, Fe₃O₄/polystyrene/poly(N‐isopropylacryl amide‐co‐methylacrylate acid) (Fe₃O₄/PS/P(NIPAAM‐co‐MAA)) magnetic composite latex was synthesized by the method of two stage emulsion polymerization. In this reaction system, 2,2′‐azobis(2‐methyl propionamidine) dihydrochloride (AIBA) was used as initiator to initiate the first stage reaction and second stage reaction. The Fe₃O₄ particles were prepared by a traditional coprecipitation method. Fe₃O₄ particles were surface treated by either PAA oligomer or lauric acid to form the stable ferrofluid. The first stage for the synthesis of magnetic composite latex was to synthesize PS in the presence of ferrofluid by soapless emulsion polymerization to form the Fe₃O₄/PS composite latex particles. Following the first stage of reaction, the second stage of polymerization was carried out by the method of soapless emulsion polymerization with NIPAAM and MAA as monomers and Fe₃O₄/PS latex as seeds. The magnetic composite particles, Fe₃O₄/PS/P(NIPAAM‐co‐MAA), were thus obtained. The mechanism of the first stage reaction and second stage reaction were investigated. Moreover, the effects of PAA and lauric acid on the reaction kinetics, morphology, and particle size distribution were studied. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3912–3921, 2007     

Synthesis,characterization, and emulsion polymerization of polymerizable coumarin derivatives

We describe the synthesis of a new polymerizable coumarin derivative, [6‐(β‐acryloxyethoxy)‐7‐isopropoxy‐4‐methyl coumarin ( 3 )], whose UV absorption spectrum significantly overlaps the emission spectrum of 9‐alkyl phenanthrene chromophore. This dye can serve several purposes in latex films. It can be a tracer for fluorescence microscopy experiments, or it can act as a donor or acceptor dye in nonradiative energy transfer experiments. Here we emphasize its role as an energy transfer acceptor in experiments with phenanthrene as the corresponding donor. Coumarin‐labeled poly(butyl methacrylate) latex dispersions could be synthesized by conventional batch emulsion polymerization with complete monomer conversion, complete dye incorporation, and uniform dye distribution. Attempts to extend this reaction to poly(vinyl acetate) copolymers failed because the dye inhibited monomer conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3479–3489, 2004     

Naphthodioxinone‐1,3‐benzodioxole as photochemically masked one‐component type II photoinitiator for free radical polymerization

A 1,3‐benzodioxole derivative of naphthodioxinone, namely 2‐(benzo[d][1,3]dioxol‐5‐yl)‐9‐hydroxy‐2‐phenyl‐4H‐naphtho[2,3‐d][1,3]dioxin‐4‐one was synthesized and characterized. Its capability to act as caged one‐component Type II photoinitiator for free radical polymerization was examined. Upon irradiation, this photoinitiator releases 5‐benzoyl‐1,3‐benzodioxole possessing both benzophenone and 1,3‐dioxole groups in the structure as light absorbing and hydrogen donating sites, respectively. Subsequent photoexcitation of the benzophenone chromophore followed by hydrogen abstraction generates radicals capable of initiating free radical polymerization of appropriate monomers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

表面活性单体存在下的MMA／BA乳液共聚合（Ⅱ）：聚合动力？…

研究了表面活性单体「磺化－十二醇－烯丙基甘油－丁二酸酯钠盐（ＺＣ－Ｌ）」的用量对ＭＭＡ／ＢＡ／ＺＣ－Ｌ乳液聚合速率和粒径的影响,用Ｃｏｒｌｔｉｒ ＬＳ２３０型激光粒径分析仪测定聚合过程中乳液的粒径和粒径分布变化,并与ＭＭＡ／ＢＡ无皂乳液聚合及十二烷基苯磺酸钠存在下的ＭＭＡ／ＢＡ乳液聚合作了比较。「ＺＣ－Ｌ」〈ＣＭＣ时,成核机理为均相成核机理,乳胶粒需依靠粒子间的凝聚来提高表面电荷密度而稳定;「ＺＣ     

表面活性单体存在下的MMA/BA乳液共聚合(Ⅱ)聚合动力学及机理

研究了表面活性单体[磺化-十二醇-烯丙基甘油-丁二酸酯钠盐(ZC-L)]的用量对MMA/BA/ZC-L乳液聚合速率和粒径的影响,用CoulterLS230型激光粒径分析仪测定聚合过程中乳液的粒径和粒径分布变化,并与MMA/BA无皂乳液聚合及十二烷基苯磺酸钠存在下的MMA/BA乳液聚合作了比较.[ZC-L]CMC时,成核机理包括均相成核和胶束成核机理,生成的粒子因吸收体系中的表面活性单体而稳定存在.     

Synthesis of polymeric core–shell particles using surface‐initiated living free‐radical polymerization

An easy and novel approach to the synthesis of functionalized nanostructured polymeric particles is reported. The surfactant‐free emulsion polymerization of methyl methacrylate in the presence of the crosslinking reagent 2‐ethyl‐2‐(hydroxy methyl)‐1,3‐propanediol trimethacrylate was used to in situ crosslink colloid micelles to produce stable, crosslinked polymeric particles (diameter size ～ 100–300 nm). A functionalized methacrylate monomer, 2‐methacryloxyethyl‐2′‐bromoisobutyrate, containing a dormant atom transfer radical polymerization (ATRP) living free‐radical initiator, which is termed an inimer (initiator/monomer), was added to the solution during the polymerization to functionalize the surface of the particles with ATRP initiator groups. The surface‐initiated ATRP of different monomers was then carried out to produce core–shell‐type polymeric nanostructures. This versatile technique can be easily employed for the design of a wide variety of polymeric shells surrounding a crosslinked core while keeping good control over the sizes of the nanostructures. The particles were characterized with scanning electron microscopy, transmission electron microscopy, optical microscopy, dynamic light scattering, and Raman spectroscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1575–1584, 2007     

Synthesis,characterization, and stability of carbodiimide groups in carbodiimide‐functionalized latex dispersions and films

Cyclohexylcarbodiimidoethyl methacrylate (CCEMA) and t‐butylcarbodiimidoethyl methacrylate (t‐BCEMA) were prepared in a two‐step synthesis. These monomers were then used to prepare carbodiimide‐functionalized PBMA and PEHMA latex particles, employing two‐stage emulsion polymerization, with the carbodiimide–methacrylate monomers being introduced only in the second stage under monomer‐starved conditions. During emulsion polymerization, the carbodiimide moiety ( NCN ) was found to be unstable at pH 4, but stable when the pH of the dispersion was increased to 8, using NaHCO₃ as the buffer. Survival of  NCN group against hydrolysis during the polymerization, and during storage in the dispersion, was enhanced by using EHMA as the comonomer (more hydrophobic) and the t‐butyl carbodiimide derivative. The t‐butyl group provides more steric hindrance to the hydrolysis reaction. A decrease in the reaction temperature from 80°C to 60°C was also found to increase the extent of  NCN group incorporation during emulsion polymerization. Under ideal conditions, more than 98% of the  NCN groups in the monomer feed are successfully incorporated into the latex. When these latex particles are mixed with a  COOH containing latex and allowed to dry, polymer diffusion leading to crosslinking occurs. Films annealed at 60°C reach a gel content of 60% in 10 h. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 855–869, 2000     

Preparation and Characterization of Polymer Core Shell Latex Particles

Stable core‐shell latex was synthesized by semicontinuous seeded emulsion polymerization with core monomers consisting of styrene (St), butyl acrylate (BA), and shell monomers consisting of methyl methacrylate (MMA), eutyl acrylate (EA), and methacrylic acid (MAA). The effects of compound emulsifier amount, mass ratio of anionic/nonionic emulsifier, and initiator amount on latex performance were investigated. By particle size analysis and transmission electron microscopy (TEM) observation, results suggest that final latex particles have clearly core shell structures.     

Synthesis of amino‐functionalized latex particles by a multistep method

Cationic latex particles with surface amino groups were prepared by a multistep batch emulsion polymerization. In the first one or two steps, monodisperse cationic latex particles to be used as the seed were synthesized, and in the third step, two different amino‐functionalized monomers [aminoethylmethacrylate hydrochloride (AEMH) and vinylbenzylamine hydrochloride (VBAH)] were used to synthesize the final functionalized latex particles. 2,2′‐Azobisisobutyramidine dihydrochloride was used as the initiator, and different concentrations of two quaternary ammonium emulsifiers with hydrophobic chains of different lengths were examined. To characterize the final latexes yields were obtained gravimetrically, and particle size distributions and average particle diameters were determined by transmission electron microscopy and photon correlation spectroscopy. The amount of amino groups was determined by fluorimetry. The effect of the amino‐functional monomer used on the final latexes and the colloidal behavior of the system were studied. The influence of the different conditions utilized to synthesize the latexes on the colloidal stability of the particles was evaluated in terms of the Fuchs stability ratio and electrophoretic mobility. High yields of the amino‐functional monomers were obtained. Surface amino, amidine, and quaternary ammonium groups provided the cationic character. The colloidal stability behavior of the products obtained was compatible with their cationic character. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2929–2936, 2001     

Emulsion atom transfer radical block copolymerization of 2‐ethylhexyl methacrylate and methyl methacrylate

The emulsion atom transfer radical block copolymerization of 2‐ethylhexyl methacrylate (EHMA) and methyl methacrylate (MMA) was carried out with the bifunctional initiator 1,4‐butylene glycol di(2‐bromoisobutyrate). The system was mediated by copper bromide/4,4′‐dinonyl‐2,2′‐bipyridyl and stabilized by polyoxyethylene sorbitan monooleate. The effects of the initiator concentration and temperature profile on the polymerization kinetics and latex stability were systematically examined. Both EHMA homopolymerization and successive copolymerization with MMA proceeded in a living manner and gave good control over the polymer molecular weights. The polymer molecular weights increased linearly with the monomer conversion with polydispersities lower than 1.2. A low‐temperature prepolymerization step was found to be helpful in stabilizing the latex systems, whereas further polymerization at an elevated temperature ensured high conversion rates. The EHMA polymers were effective as macroinitiators for initiating the block polymerization of MMA. Triblock poly(methyl methacrylate–2‐ethylhexyl methacrylate–methyl methacrylate) samples with various block lengths were synthesized. The MMA and EHMA reactivity ratios determined by a nonlinear least‐square method were ～0.903 and ～0.930, respectively, at 70 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1914–1925, 2006     

Polymerization of sterically congested α‐alkylacrylates under high pressure

A series of α‐alkylacrylates, including methyl ethacrylate (MEA), methyl α‐propylacrylate, methyl α‐isopropylacrylate (MiPA), methyl α‐butylacrylate (MnBA), and methyl α‐isobutylacrylate (MiBA), were successfully polymerized at 65 °C under high pressure (1–9 kbar). In contrast to results obtained at ambient pressure, all monomers yielded high molecular weight polymers (number‐average molecular weight = 4–18 × 10⁴), except for MiPA (number‐average molecular weight = 8 × 10³), probably because of the high steric hindrance of the isopropyl group. Polymerization kinetics under high pressure were obtained for MEA, MnBA, and MiBA. Overall activation volumes were estimated to be ?14.9, ?17.0, and ?11.6 mL mol^?1 for MEA (3–7 kbar), MnBA (3–7 kbar), and MiBA (5–9 kbar), respectively. Extrapolation to ambient pressure provided rates of polymerization for these monomers unaffected by the ceiling temperature effect. These values were further used to quantitatively assess the steric influence exerted by the α‐substituent on the polymerizability of these sterically congested acrylates with Meyer's steric parameter. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 836–843, 2002; DOI 10.1002/pola.10161     

PMMA colloid particles armored by clay layers with PDMAEMA polymer brushes

Poly[2‐(dimethylamino) ethyl methacrylate] (PDMAEMA) brushes on the surfaces of clay layers were prepared by in situ free‐radical polymerization. Poly (methyl methacrylate) (PMMA) colloid particles stabilized and initiated by clay layers with PDMAEMA polymer brushes were prepared by Pickering emulsion polymerization. Transmission electron microscopy was used to characterize the structure and morphology of the colloid particles. The X‐ray diffraction (XRD) results indicated that the intercalated structures of the clay layers were almost destroyed in Pickering emulsion polymerization, and clay layers with exfoliated structures were created. The surface of the colloid particles was analyzed by using X‐ray photoelectron spectroscopy (XPS). The XPS results provide direct evidence that the clay layers with PDMAEMA chains cover the PMMA colloid particles. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 2632–2639, 2008     

Emulsion polymerization of divinyl monomers stabilized by sodium dodecyl sulfate and bis(2‐ethylhexyl)sulfosuccinate sodium salt

The emulsion polymerization of divinyl monomers is investigated. Emulsions were obtained in the presence of sodium dodecyl sulfate and bis(2‐ethylhexyl)sulfosuccinate sodium salt as surfactants. The influence of monomer type and kind of surfactant on the particle size distribution is studied. The porous structure of the broken emulsions is also determined. The results indicate that the diameter of nanospheres obtained from two divinyl monomers are significantly larger than those obtained from polystyrene. Aggregation of the particles and the pore‐forming diluent added to the emulsion are responsible for the existence of pores. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3967–3973, 2002     

半互穿聚合物网络BVV的制备及其性能研究

以丙烯酸丁酯(BA)和醋酸乙烯酯(VAc)为单体,对VAc与乙烯的共聚乳液(VAE)进行改性,通过乳液聚合制备了半互穿聚合物网络BVV.考察了乳化剂、交联剂、引发剂以及反应时间等条件对转化率及BVV稳定性的影响.BVV的剥离力度及其乳胶膜的吸水率的测定结果证明BVV耐水性及粘接强度较VAE明显增强.光学显微镜照片显示BVV的互穿结构已经形成.     

纳米SiO_2/聚丙烯酸酯复合乳液的制备与表征

根据核壳乳液聚合理论,以经过硅烷偶联剂表面改性的纳米SiO2为种子,采用适当的乳液聚合工艺,制备了纳米SiO2/聚丙烯酸酯复合乳液,并表征了其性能.结果表明,纳米SiO2经过改性后,硅烷偶联剂接枝在其表面;以其为种子制备的复合乳液具有核壳结构,其热稳定性有所提高.     

Preparation of novel suspensions of ZnO/living block copolymer latex nanoparticles via pickering emulsion polymerization and their long term stability

In this work, we present the first Pickering emulsion polymerization with a controlled/living character. Pickering emulsion polymerization in the presence of a novel suspension of zinc oxide/poly(sodium 4‐styrenesulfonate) (ZnO/PSS^?) nanocomposite particles was applied to prepare ZnO/living block copolymer latexes. In the emulsion system, 1,1‐diphenylethene (DPE)‐controlled radical polymerization of poly(methyl methacrylate)‐b‐poly(butyl acrylate) (PMMA‐b‐PBA) was proceeded in oil phase. The nanocomposite particles of ZnO/PSS^? with an average diameter of 20 nm and negatively charged zeta potential around ?30 mV were synthesized via hydrothermal method then served as an effective emulsion stabilizer at the oil/water interface. Living polymerization was carried out using DPE‐capped PMMA as the macroinitiator and PMMA‐b‐PBA block copolymer latex was successfully prepared with coverage of ZnO/PSS^? nanoparticles. Narrow size distributions of the droplets as well as latex particles were obtained, and the livingness of block copolymers was comparable to that of emulsions stabilized by conventional surfactants. The controlled/living character in Pickering emulsion polymerization was slightly influenced by the amount of PSS^? immobilized into the ZnO/PSS^? nanoparticles, whereas it was significantly influenced by the weight ratios between ZnO/PSS^? and oil phase. The Pickering latexes showed excellent long term stability against either coalescence or sedimentation over several months. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

DESIGN AND CONTROL OF SOAP-FREE HYDROPHILIC-HYDROPHOBIC CORE-SHELL LATEX PARTICLES WITH HIGH CARBOXYL CONTENT IN THE CORE OF THE PARTICLES

Soap-free hydrophilic-hydrophobic core-shell latex particles with high carboxyl content in the core of the particles were synthesized via the seeded emulsion polymerization using methyl methacrylate(MMA),butyl acrylate(BA), methacrylic acid(MAA),styrene(St)and ethylene glycol dimethacrylate(EGDMA)as monomers,and the influences of MMA content used in the core preparation on polymerization,particle size and morphology were investigated by transmission electron microscopy,dynamic light scattering and conductometric titration.The results showed that the seeded emulsion polymerization could be carried out smoothly using "starved monomer feeding process" when MAA content in the core preparation was equal to or less than 24 wt%,and the encapsulating efficiency of the hydrophilic P(MMA-BA-MAAEGDMA) core with the hydrophobic PSt shell decreased with the increase in MAA content.When an interlayer of P(MMAMAA -St)with moderate polarity was inserted between the P(MMA-BA-MAA-EGDMA)core and the PSt shell,well designed soap-free hydrophilic-hydrophobic core-shell latex particles with 24 wt%MAA content in the core preparation were obtained.     

Copper(0)‐mediated radical copolymerization of vinyl acetate and acrylonitrile in DMSO at ambient temperature

In this work, Cu(0)‐mediated radical copolymerization of vinyl acetate (VAc) and acrylonitrile (AN) was explored. The polymerization was carried out at 25°C with 2,2′‐bipyridine as ligand and dimethyl sulfoxide as solvent. The copolymerization proceeded smoothly producing moderately controlled molecular weights at low VAc feed ratios. The high VAc feed ratios generated low polymerization rate and poorly controlled molecular weights. FTIR, ¹H NMR, and differential scanning calorimetry confirmed the successful obtaining of the copolymers. Based on ¹H NMR spectra, the reactivity ratios of VAc and AN were calculated to be 0.003 and 1.605, respectively. This work conveyed the first example for the Cu(0)‐mediated radical polymerization of AN and VAc, wherein VAc cannot be homopolymerized by Cu(0)‐mediated radical polymerization technique. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Polar Gradient Latex Particles with Hydrophilic Core and Hydrophobic Shell Prepared via Multistep Emulsion Polymerization

Monodisperse polar gradient particles were synthesized via a three‐step emulsion polymerization using poly(butyl acrylate‐methyl methacrylate‐methacrylic acid‐ethylene glycol dimethacrylate) (P(BA‐MMA‐MAA‐EGDMA)) as core, poly(methyl methacrylate‐methacrylic acid‐styrene) (P(St‐MMA‐MAA)) as interlayer and polystyrene (PSt) as shell. The particle growth and encapsulation in each emulsion polymerization step were followed by transmission electron microscopy (TEM), dynamic light scattering (DLS) and conductometric titration. Results indicated that the feeding mode and the interlayer were essential to prepare the polar gradient latex particles with hydrophilic core and hydrophobic shell. The morphologies of the two‐layer core/interlayer and three‐layer core/interlayer/shell particles were observed in TEM micrographs, and the sequential encapsulations of the carboxyl‐containing core and the core/interlayer particles were confirmed by an increase in the particle size as well as an increase in the buried carboxyl percentage.