Preparation and structure control of hollow polymer particles: Influence of seeded emulsion polymerization and alkalization treatment process

Hollow polymer latex particles containing a hydrophilic core were prepared by seeded emulsion polymerization with MAA/BA/MMA/St as comonomers, followed by stepwise alkalization treatment with ammonia. The size and morphology of composite latex particles was determined by TEM. The effects of the seeded emulsion polymerization conditions and alkalization treatment on the size and hollow structure of latex were investigated. The results showed that the optimum content of crosslinking agent in the shell polymers was about 0.5–1.0 wt %, emulsifier was about 0.8–1.1 wt %, and the core/shell weight ratio was 1/7. To obtain uniform hollow latex particles with large size, the starved feeding technique should be adopted in seeded emulsion polymerization, and the neutralization temperature should equal to the T_g of the shell polymer. Then, the obtained polymer particles under this condition had an excellent hollow structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of CaCO3–P(MMA–BA) nanocomposite and its application in water based alkyd emulsion coating

As part of broader effort to synthesize a new class of water-based composite, hybrid emulsion polymerization was carried out with acrylic monomers [methyl methacrylate (MMA), n-butyl acrylate (BA)]. Nanocomposite of P(MMA–BA)/nano CaCO₃ was synthesized by in situ emulsion polymerization. Water-based alkyd coating with various proportions nano CaCO₃, P(MMA–BA) and its nanocomposite was formulated. Extent of polymerization with and without nano CaCO₃ was measured using gravimetric method. Thermal properties of neat polymer, nanocomposite and coating films were evaluated by TGA and DSC, DTA analysis. Uniform dispersion of nano CaCO₃ in polymer matrix was ensured from SEM/TEM images. Incorporation of nanoparticles to hybrid polymer and nanocomposite to alkyd emulsion showed significant enhancement in mechanical and thermal properties. Dual role of nanocomposite in coating; as a partial binder and a filler to improve property profile of neat coating has been reported.     

Synthesis and characterization of nanosilica/polyacrylate composite latex

The nanosilica/polyacrylate organic–inorganic composite latex was synthesized by in‐situ emulsion polymerization of methyl methacrylate (MMA) and butyl acrylate (BA) in the presence of silica nanoparticles, which were modified by silane coupling agent. The surface properties and dispersibility of silica nanoparticles modification, chemical structure, Zeta potential, diameter distribution of the composite latex prepared, surface roughness, and thermal stability of the hybrid film formed by the composite latex were investigated by fourier transform infrared spectrometer (FTIR), transmission electron microscopy (TEM), Zeta meter, ZetaPlus apparatus (dynamic light scattering method), atomic force microscopy (AFM), and thermogravimetric analysis (TGA), respectively. After modification with silane coupling agent, silane was grafted onto the surface of silica nanoparticles to form the organic layers, which was able to efficiently prevent the silica nanoparticles from aggregating to individually homogeneous disperse in the in‐situ emulsion polymerization system and improve the compatibility of silica nanoparticles with the acrylate monomers. The nanosilica/polyacrylate organic–inorganic composite latex prepared had the properties of silica nanoparticles and pure polyacrylate latex but was not simply a combination. Strong chemical bonding tethered the silica and acrylate chains to form the core/shell structural composite latex. Consequently, the hybrid film formed by nanosilica/polyacrylate composite latex exhibited a smooth surface and better thermal properties than the pure polyacrylate film. POLYM. COMPOS. 27:282–288, 2006. © 2006 Society of Plastics Engineers     

Study on ultrasonic induced encapsulating emulsion polymerization in the presence of nanoparticles

In this paper, the ultrasonic induced encapsulating emulsion polymerization technique was used to prepare polymer/inorganic nanoparticle composites. The main affecting factors in ultrasonic induced encapsulating emulsion polymerization were studied systematically. The experimental results suggested that the pH value, the type of monomers, the type, content, and surface properties of nanoparticles, the type and concentration of surfactant have great influence on the ultrasonic induced encapsulating emulsion polymerization and the obtained latex stability. If selecting cationic emulsifier (such as cetyl trimethylammonium bromide), low water soluble monomer (such as n‐butyl acrylate and styrene), and hydrophobic nano silica, the inorganic nanoparticles could be encapsulated by polymers through ultrasonic irradiation successfully under alkalescent condition, forming a novel polymer/inorganic nanoparticles composite. The mechanism of ultrasonic induced encapsulating emulsion polymerization and the composite latex stabilization are proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1130–1139, 2001     

Synthesis and characterization of poly(butyl acrylate–methyl methacrylate)/polyaniline core–shell latexes

Poly(butyl acrylate–methyl methacrylate) [P(BA–MMA]/polyaniline (PANI) core–shell complex particles were synthesized with a two‐step emulsion polymerization method with P(BA–MMA) as the core and PANI as the shell. The first step was to prepare P(BA–MMA) latex particles as the core via soapless emulsion polymerization. The second step was to prepare P(BA–MMA)/PANI core–shell particles. Sodium dodecyl sulfate was fed into the P(BA–MMA) emulsion as a surfactant, and this was followed by the addition of the aniline monomer. A bilayer structure of the surfactant over the surfaces of the core particles was desired so that the aniline monomer could be attracted near the outer surface of the core particles. In some cases, dodecyl benzene sulfonic acid was added after 2 h when the polymerization of aniline was started. The final product was the desired core–shell particles. The morphology of P(BA–MMA) and P(BA–MMA)/PANI particles was observed with transmission electron microscopy. The thermal properties were studied with thermogravimetric analysis and differential scanning calorimetry. Furthermore, conductive films made from the core–shell latexes were prepared, and the electrical conductivities of the films were studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 823–830, 2007     

Preparation of polystyrene/poly(methyl methacrylate) core‐shell composite particles by suspension‐emulsion combined polymerization

Suspension‐emulsion combined polymerization process, in which methyl methacrylate (MMA) emulsion polymerization constituents (EPC) were drop wise added to styrene (St) suspension polymerization system, was applied to prepare polystyrene/poly(methyl methacrylate) (PS/PMMA) composite particles. The influences of the feeding condition and the composition of EPC on the particle feature of the resulting composite polymer particles were investigated. It was found that PS/PMMA core‐shell composite particles with a narrow particle size distribution and a great size would be formed when the EPC was added at the viscous energy dominated particle formation stage of St suspension polymerization with a suitable feeding rate, whereas St‐MMA copolymer particles or PS/PMMA composite particles with imperfect core‐shell structure would be formed when the EPC was added at the earlier or later stage of St suspension polymerization, respectively. It was also showed that the EPC composition affected the composite particles formation process. The individual latex particles would exist in the final product when the concentrations of MMA monomer, sodium dodecyl sulfate emulsifier, and potassium persulfate initiator were great in the EPC. Considering the feature of St suspension polymerization and the morphology of PS/PMMA composite particles, the formation mechanism of PS/PMMA particles with core‐shell structure was proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

核/壳型聚硅氧烷丙烯酸酯复合乳液的制备

采用种子乳液聚合的方法制备了具有核/壳结构的聚硅氧烷丙烯酸酯复合乳液,研究了乳化剂、单体的投料方式及配比对乳液性质的影响。结果表明:通过种子乳液聚合,得到了含氢聚硅氧烷/丙烯酸丁酯/苯乙烯/甲基丙烯酸甲酯/甲基丙烯酸（PHMS/BA/St/MMA/MAA）共聚物复合乳液,乳液性能稳定,该乳液所制得的胶膜具有优良的性能。     

Synthesis and characterization of poly(butyl acrylate)/silica and poly(butyl acrylate)/silica/poly(methyl methacrylate) composite particles

Poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core–shell particles embedded with nanometer‐sized silica particles were prepared by emulsion polymerization of butyl acrylate (BA) in the presence of silica particles preabsorbed with 2,2′‐azobis(2‐amidinopropane)dihydrochloride (AIBA) initiator and subsequent MMA emulsion polymerization in the presence of PBA/silica composite particles. The morphologies of the resulting PBA/silica and PBA/silica/PMMA composite particles were characterized, which showed that AIBA could be absorbed effectively onto silica particles when the pH of the dispersion medium was greater than the isoelectric potential point of silica. The critical amount of AIBA added to have stable dispersion of silica particles increased as the pH of the dispersion medium increased. PBA/silica composite particles prepared by in situ emulsion polymerization using silica preabsorbed with AIBA showed higher silica absorption efficiency than did the PBA/silica composite particles prepared by direct mixing of PBA latex and silica dispersion or by emulsion polymerization in which AIBA was added after the mixing of BA and silica. The PBA/silica composite particles exhibited a raspberrylike morphology, with silica particles “adhered” to the surfaces of the PBA particles, whereas the PBA/silica/PMMA composite latex particles exhibited a sandwich morphology, with silica particles mainly at the interface between the PBA core and the PMMA shell. Subsequently, the PBA/silica/PMMA composite latex obtained had a narrow particle size distribution and good dispersion stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3425–3432, 2006     

Emulsifier‐minor emulsion copolymerization of BA‐MMA‐St‐MAA (or AA)‐N‐MA

A novel emulsion polymerization technique referred to as emulsifier‐minor emulsion polymerization was achieved by the copolymerization of methyl methacrylate, butyl acrylate, and styrene (MMA‐BA‐St) with a combination of water‐soluble ionic monomers [methacrylic acid (MAA) or acrylic acid (AA)] and nonionic monomers (N‐methylol acrylamide). In the technique, water‐soluble monomers play a crucial role in the stabilization of the latex particles as they can be bound to the particle surface and form a hydrate protective layer, which exhibits steric and/or electrostatic effects to prevent particle coagulation. The minor but over its critical micelle concentration emulsifier sodium alkylated diphenyl ether disulfonate (DSB) results in the nucleation of particles mainly by the micelle nucleation mechanism and thus determines the polymerization rate, the particle size, and the number. The film water resistance of the latices can be improved, and the foaming capacity of can be lowered by using technique instead of conventional emulsion polymerization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2923–2929, 2004     

Study on the synthesis of poly(methyl methacrylate)–poly(methacrylic acid) composite latex and their humidity sensitive properties

The composite latex particles of poly(methyl methacrylate)–poly(methacrylic acid) [poly(MMA–MAA)] were synthesized through either soapless seeded emulsion polymerization or a soapless emulsion copolymerization technique. The reaction kinetics, morphology, and size of latex particles, composition, glass transition temperature (T_g), and molecular weight of polymer products were studied under different experimental conditions. Moreover, this work also focused on the humidity‐sensitive properties of the polymer films fabricated by melting under the temperature of 200°C and followed by chemical modification with aqueous solution of NaOH. It is confirmed that there exists both an optimum ratio of hydrophilic to hydrophobic monomers and the initial structure of the latex particle to provide the humidity‐sensitive polyelectrolyte film with excellent water resistivity and good sensitivity to humidity. Besides, little hysteresis and quick response were observed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 47–57, 1999     

Preparation of monodispersed hollow polymer particles by seeded emulsion polymerization under low emulsifier conditions

In a low emulsifier system, the MMA‐BA‐MAA copolymer emulsions were prepared as seed latices and the seeded emulsion polymerization of MMA‐MAA‐DVB was consequently carried out to prepare carboxylated core particles. The hydrophobic shell was then synthesized onto the core using styrene, acrylonitrile, and divinylbenzene as comonomers. The hollow latex particles were obtained by alkalization treatment of the core‐shell latex particles. The effects of the feeding rate of monomer mixture, contents of emulsifier SDBS and crosslinking agent DVB, and ratio of the monomers during the core stage and shell stage on the morphology and volume expansion of the latex particles were investigated. The results show that the monodispersed hollow latex particles with large size can be obtained when the feeding rate is 0.1 g/min, SDBS content is 0.15 and 0.2 wt % during the core stage and shell stage, respectively, DVB contents are 1% during the preparation of shell copolymers, and the monomer ratio of the core particle to shell layer is 1 : 8. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1505–1510, 2005     

Polymer latex containing carboxylic acid functional groups. I. Synthesis of polymer latex from MMA and AA

The polymer latex of poly(MMA‐AA) was synthesized using two techniques: soapless seeded emulsion polymerization, and the soapless emulsion copolymerization technique. The reaction kinetics, morphology, composition, and size of latex particles, as well as the structure using thin‐layer chromatographic separation techniques, glass transition temperature (T_g), and molecular weight of polymer products, were studied under different experimental conditions. The reaction of the hydrophilic AA monomer took place in two places—on or in the latex particles, and in the water phase. Therefore, the polymer latex, whose size is very small and uniform, dispersed uniformly all over the PAA continuous phase. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3111–3120, 1999     

核壳型纳米SiO2/含氟聚丙烯酸酯复合乳液的合成与表征

采用原位乳液聚合法,在可聚合阴离子乳化剂/非离子乳化剂复配体系下,以γ-甲基丙烯酰氧丙基三甲氧基硅烷(KH-570)改性的纳米SiO2、甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸(AA)等为核相组成,以MMA、BA及甲基丙烯酸十二氟庚酯(DFMA)为壳相单体,合成纳米SiO2/含氟聚丙烯酸酯复合乳液.考察了纳...     

Synthesis and evaluation of fluorosilicone‐modified starch for protection of historic stone

Starch is sensitive to moisture and is weak to durability in the protection application to ancient relics. Therefore, two fluorosilicone‐modified starches are firstly prepared and evaluated for the protection of historic stones. The fluoro‐silicone copolymer grafted starch of P(VTMS/12FMA)‐g‐starch is synthesized by grafting copolymer of vinyltrimethoxysilane (VTMS) and dodecafluoroheptyl methacrylate (12FMA) onto starch. While the fluoro‐silicone starch latex of VTMS‐starch@P(MMA/BA/3FMA) is obtained by emulsion polymerization of VTMS primarily grafted‐starch (VTMS‐starch) with methyl methacrylate (MMA), butyl acrylate (BA) and 2,2,2‐trifluoroethyl methacrylate (3FMA). The grafting fluorosilicone copolymer onto starch improves obviously their hydrophobic and thermal properties. Comparatively, VTMS‐starch@P(MMA/BA/3FMA) film performs higher water contact angle (107°) and thermal stability (350–430°C) than p(VTMS/12FMA)‐g‐starch film (72°, 250–420°C) due to the migration of fluorine‐containing group onto the surface of film during the film formation. Therefore, VTMS‐starch@P(MMA/BA/3FMA) shows much better protective performance in water‐resistance, and salt/freeze‐thaw resistance for stone samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41650.     

Synthesis and characterization of poly(methyl methacrylate–butyl acrylate–acrylic acid)/polyaniline core–shell nanoparticles in miniemulsion media

Conductive polymer particles, polyaniline (PANI)‐coated poly(methyl methacrylate–butyl acrylate–acrylic acid) [P(MMA–BA–AA)] nanoparticles, were prepared. The P(MMA–BA–AA)/PANI core–shell complex particles were synthesized with a two‐step miniemulsion polymerization method with P(MMA–BA–AA) as the core and PANI as the shell. The first step was to prepare the P(MMA–BA–AA) latex particles as the core via miniemulsion polymerization and then to prepare the P(MMA–BA–AA)/PANI core–shell particles. The aniline monomer was added to the mixture of water and core nanoparticles. The aniline monomer could be attracted near the outer surface of the core particles. The polymerization of aniline was started under the action of ammonium persulfate (APS). The final product was the desired core–shell nanoparticles. The morphology of the P(MMA–BA–AA) and P(MMA–BA–AA)/PANI particles was characterized with transmission electron microscopy. The core–shell structure of the P(MMA–BA–AA)/PANI composites was further determined by Fourier transform spectroscopy and ultraviolet–visible measurements. The conductive flakes made from the core–shell latexes were prepared, and the electrical conductivities of the flakes were studied. The highest conductivity of the P(MMA–BA–AA)/PANI pellets was 2.05 S/cm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and comparative evaluation of well-defined fluorinated acrylic copolymer latex and solution for ancient stone protection

In this work the well-defined fluorinated acrylic copolymer latex and solution were prepared by the radical initiated seed emulsion polymerization and solution polymerization, respectively, using the same monomers of dodecafluoroheptyl methacrylate (DFHM), butyl acrylate (BA) and methyl methylacrylate (MMA). The copolymer latex BA/MMA/DFHM was designed as core–shell structure and the copolymer solution poly(BA–MMA–DFHM) was structured with low molecular weight. The chemical and morphology structures as well as the film properties obtained from latex and solution were analyzed and compared by spectroscopic techniques (FT-IR and NMR), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), scanning electron microscopy coupled with energy-dispersive X-ray detector (SEM–EDX) and static contact angles (CAs) instrument. Moreover, the BA/MMA/DFHM latex and poly(BA–MMA–DFHM) solution (with 29 wt% of DFHM) were applied onto two kinds of sandstone samples by capillary absorption, and their preliminary protecting efficiency was evaluated. It is demonstrated that the comprehensive performances of BA/MMA/DFHM latex films were quite comparable to those of poly(BA–MMA–DFHM) solution cast films, the latter exhibited a better protective performance.     

乙烯基硅烷改性丙烯酸酯乳液的合成及性能研究

采用种子乳液聚合法制备了经乙烯基三乙氧基硅烷(VTES)改性,具有核壳结构的甲基丙烯酸甲酯(MMA)/丙烯酸丁酯(BA)/丙烯腈(AN)复合耐水硅丙乳液,研究了VTES用量对乳液及乳液胶膜性能的影响。结果表明:乳胶膜吸水率受有机硅VTES的影响很小;随着VTES用量增大,乳胶膜力学性能及其保持率都升高;当VTES用量为5%时,乳液及乳液胶膜的综合性能最好。     

Morphologies and dynamic mechanical properties of core‐shell emulsifier‐free latexes and their copolymers for P(BA/MMA)/P(MMA/BA) and P(BA/MMA)/PSt systems in the presence of AHPS

Different poly(methyl methacrylate/n‐butyl acrylate)/poly(n‐butyl acrylate/methyl methacrylate) [P(BA/MMA)/P(MMA/BA)] and poly(n‐butyl acrylate/methyl methacrylate)/polystyrene [P(BA/MMA)/PSt] core‐shell structured latexes were prepared by emulsifier‐free emulsion polymerization in the presence of hydrophilic monomer 3‐allyloxy‐2‐hydroxyl‐propanesulfonic salt (AHPS). The particle morphologies of the final latexes and dynamic mechanical properties of the copolymers from final latexes were investigated in detail. With the addition of AHPS, a latex of stable and high‐solid content (60 wt %) was prepared. The diameters of the latex particles are ～0.26 μm for the P(BA/MMA)/P(MMA/BA) system and 0.22–0.24 μm for the P(BA/MMA)/PSt system. All copolymers from the final latexes are two‐phase structure polymers, shown as two glass transition temperatures (T_gs) on dynamic mechanical analysis spectra. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3078–3084, 2002     

Transparent poly(methyl methacrylate‐co‐butyl acrylate) nanofibers

Nanofibers of n‐Butyl Acrylate/Methyl Methacrylate copolymer [P(BA‐co‐MMA)] were produced by electrospinning in this study. P(BA‐co‐MMA) was synthesized by emulsion polymerization. The structural and thermal properties of copolymers and electrospun P(BA‐co‐MMA) nanofibers were analyzed using Fourier transform infrared spectroscopy–Attenuated total reflectance (FTIR–ATR), Nuclear magnetic spectroscopy (NMR), and Differential scanning calorimetry (DSC). FTIR–ATR spectra and NMR spectrum revealed that BA and MMA had effectively participated in polymerization. The morphology of the resulting nanofibers was investigated by scanning electron microscopy, indicating that the diameters of P(BA‐co‐MMA) nanofibers were strongly dependent on the polymer solution dielectric constant, and concentration of solution and flow rate. Homogeneous electrospun P(BA‐co‐MMA) fibers as small as 390 ± 30 nm were successfully produced. The dielectric properties of polymer solution strongly affected the diameter and morphology of electrospun polymer fibers. The bending instability of the electrospinning jet increased with higher dielectric constant. The charges inside the polymer jet tended to repel each other so as to stretch and reduce the diameter of the polymer fibers by the presence of high dielectric environment of the solvent. The extent to which the choice of solvent affects the nanofiber characteristics were well illustrated in the electrospinning of [P(BA‐co‐MMA)] from solvents and mixed solvents. Nanofiber mats showed relatively high hydrophobicity with intrinsic water contact angle up to 120°. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4264–4272, 2013     

In situ preparation and properties of high‐solid‐content and low‐viscosity poly(methyl methacrylate/n‐butyl acrylate/acrylic acid)/poly(styrene/acrylic acid) composite latexes

With monodispersed poly(methyl methacrylate/n‐butyl acrylate/acrylic acid) [P(MMA/BA/AA)] seeded latex with a particle size of 485 nm and a solid content of 50 wt % as a medium, a series of stable P(MMA/BA/AA)/poly(styrene/acrylic acid) composite latexes with a high solid content (70 wt %) and low viscosities (500–1000 mPa · s when the shear rate was 21 s^?1) was prepared in situ via simple two‐step semicontinuous monomer adding technology. The coagulum ratio of polymerization was about 0.05 wt %. The particle size distribution of such latexes was bimodal, in which the large particle was about 589 nm and the small one was about 80 nm. The latexes combined good mechanical properties with good film‐forming properties. Differential scanning calorimetry showed that the corresponding latex film had a two‐phase structure. The morphology of the latex film was characterized with atomic force microscopy and scanning electron microscopy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1815–1825, 2007