Synthesis of raspberry‐like silica/polystyrene/silica multilayer hybrid particles via miniemulsion polymerization

Organic–inorganic hybrid particles have many potential applications, but almost all research has been focused on hybrid particles with one kind of inorganic nanoparticle. This article presents a novel and facile preparation approach for raspberry‐like silica/polystyrene/silica multilayer hybrid particles via miniemulsion polymerization. In this method, larger, surface‐modified silica particles are first dispersed into monomer droplets to form a miniemulsion, and then raspberry‐like silica/polystyrene/silica multilayer hybrid particles are directly obtained when miniemulsion polymerization is performed in the presence of smaller, unmodified silica particles with 4‐vinylpyridine as an auxiliary monomer. Influential parameters such as the amount of 4‐vinylpyridine, the surfactant concentration, and the pH value of the system have been investigated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1028–1037, 2007     

Synthesis and characterization of positively charged,alumina‐coated silica/polystyrene hybrid nanoparticles via pickering miniemulsion polymerization

Positively charged, raspberry‐like hybrid nanoparticles, consisting of a polystyrene core and an alumina‐coated silica shell were successfully prepared in a surfactant free system via the radical copolymerization of styrene (St) and different comonomers (acrylic acid, methacrylic acid, and acrylamide) by using a cationic silica sol as the sole emulsifier in Pickering miniemulsion polymerization. The influence of different parameters like pH of the dispersion, comonomer content, and the amount and size of silica nanoparticles on the colloidal stability of the systems, prepared with different comonomers, was examined. The particles' morphology was observed via high‐resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The removal of free silica particles via centrifugation was proved by TEM and SEM, and the content of free and adsorbed silica was quantified via thermogravimetric analysis (TGA). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of oily core‐hybrid shell nanocapsules through interfacial free radical copolymerization in miniemulsion: Droplet formation and nucleation

Nanocapsules with an oily core and an organic/inorganic hybrid shell were elaborated by miniemulsion (co)polymerization of styrene, divinylbenzene, γ‐methacryloyloxy propyl trimethoxysilane, and N‐isopropyl acrylamide. The hybrid copolymer shell membrane was formed by polymerization‐induced phase separation at the interface of the oily nanodroplets with water. It was shown that the size, size distribution, and colloidal stability of the miniemulsion droplets were extremely dependent on the nature of the oil phase, the monomer content and the surfactant concentration. The less water‐soluble the hydrocarbon template and the higher the monomer content, the better the droplet stability. The successful formation of nanocapsules with the targeted core‐shell morphology (i.e., a liquid core surrounded by a solid shell) was evidenced by cryogenic transmission electron microscopy. Both nanocapsules and nanoparticles were produced by polymerization of the miniemulsion droplets. The proportion of nanoparticles increased with increasing monomer concentration in the oil phase. These undesirable nanoparticles were presumably formed by homogeneous nucleation as we showed that micellar nucleation could be neglected under our experimental conditions even for high surfactant concentrations. The introduction of γ‐methacryloyloxy propyl trimethoxysilane was considered to be the main reason for homogeneous nucleation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 593–603, 2010     

Synthesis of polymeric nanocapsules with a crosslinked shell through interfacial miniemulsion polymerization

A water‐soluble comonomer, N‐isopropylacrylamide (NIPAM), and an oil‐soluble crosslinker, divinylbenzene (DVB), have been combined in a system for the synthesis of nanocapsules with crosslinked shells through interfacial miniemulsion polymerization by encapsulating a liquid nonsolvating hydrocarbon. Oligomers of poly(N‐isopropylacrylamide) (PNIPAM) were dehydrated and separated from the aqueous phase and were adsorbed by the nanodroplets or latex particles and then anchored at their interfaces by means of a crosslinking reaction. Nanocapsules were then formed through encapsulation of the hydrocarbon by the newly produced polymers at the interfaces of the droplets. The crosslinked structure gradually grew to stabilize the shell morphology. The incorporation of NIPAM into the shell copolymers has been verified by FTIR and solid‐state ¹³C NMR data. The fact that the number of nanocapsules increases with increasing amounts of DVB and NIPAM supports the formation of nanocapsules following interfacial (co)polymerization. Therefore, a mechanism for the formation of nanocapsules through interfacial (co)polymerization induced by NIPAM and DVB is proposed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1522–1534, 2009     

Liquid‐crystalline organic–inorganic hybrid polymers with functionalized silsesquioxanes

Liquid‐crystalline (LC) hybrid polymers with functionalized silsesquioxanes with various proportions of LC monomer were synthesized by the reaction of polyhedral oligomeric silsesquioxane (POSS) macromonomer with methacrylate monomer having an LC moiety under common free‐radical conditions. The obtained LC hybrid polymers were soluble in common solvents such as tetrahydrofuran, toluene, and chloroform, and their structures were characterized with Fourier transform infrared, ¹H NMR, and ²⁹Si NMR. The thermal stability of the hybrid polymers was increased with an increasing ratio of POSS moieties as the inorganic part. Because of the steric hindrance caused by the bulkiness of the POSS macromonomer, the number‐average molecular weight of the hybrid polymers gradually decreased as the molar percentage of POSS in the feed increased. Their liquid crystallinities were very dependent on the POSS segments of the hybrid polymers behaving as hard, compact components. The hybrid polymer with 90 mol % LC moiety (Cube‐LC90) showed liquid crystallinity, larger glass‐transition temperatures, and better stability with respect to the LC homopolymer. The results of differential scanning calorimetry and optical polarizing microscopy showed that Cube‐LC90 had a smectic‐mesophase‐like fine‐grained texture. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4035–4043, 2001     

Synthesis and characterization of organic–inorganic hybrid block copolymers containing a fully condensed ladder‐like polyphenylsilsesquioxane

A series of inorganic–organic hybrid block copolymers were synthesized via atom transfer radical polymerization using a fully condensed, ladder‐like structured polyphenylsilsesquioxane end‐functionalized macroinitiator. The inorganic portion, ladder‐like polyphenylsilsesquioxane, was synthesized in a one‐batch, base‐catalyzed system, whereas organic hard and soft monomers, styrene, and n‐butyl acrylate, were polymerized and copolymerized on the ends of the linear, inorganic backbone. Synthesized hybrid diblock, triblock, and random copolymers were characterized by ¹H NMR, ²⁹Si NMR, gel permeation chromatography, static light scattering, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Hybrid block copolymers were well‐defined with low polydispersity (<1.4) and exhibited enhanced thermal properties in the form of increased glass transition and degradation onset temperatures over their organic analogues.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Photopolymerization of hydroxyethylmethacrylate in the formation of organic–inorganic hybrid sol–gel matrices

Hydroxyethylmethacrylate (HEMA) monomer in different contents was used in the preparation of transparent organic-inorganic hybrid sol-gel matrices. The matrices were studied by analytical techniques before and after irradiation. An increase in the homogeneity of the composite material after the irradiation of HEMA, and a chemical linkage of the monomer with the surface has been observed. Photopolymerization processes were studied by differential scanning calorimetry (DSC). Details of the irradiation times, polymerization rates, and DSC related parameters of HEMA in the sol-gel matrices are reported. © 1996 John Wiley & Sons, Inc.     

New ethyl cellulose/acrylic hybrid latexes and coatings via miniemulsion polymerization

Ethyl cellulose (EC) was incorporated into copolymer latexes via miniemulsion polymerization. The effects of EC viscosity and EC content on droplet size, particle size, and polymerization kinetics were investigated. The higher the EC content and viscosity, the larger the droplet size and the less stable the latex suspension. Small droplets that could be efficiently nucleated were formed for the lower‐viscosity EC but the latex still showed limited colloidal stability. This was attributed to some phase‐incompatibility between EC and the acrylic polymer. These stability issues were overcome by using an oil‐soluble initiator and a crosslinker. The later enabled to physically entrap EC inside the polymer particles, whereas the former allowed in situ grafting of the growing acrylic radicals to the EC backbone decreasing thereby the extent of phase separation. Thermal‐mechanical analyses evidenced that the films obtained from the hybrid latexes displayed better properties than the EC‐free latex films or the physical blends. This supports the hypothesis of formation of hybrid latexes that synergistically combine the properties of the acrylic matrix and the EC polymer. Interestingly, a significant increase of the elastic modulus was observed between 50 and 90 °C. This mechanical reinforcement was tentatively attributed to the formation of a percolating EC‐based hybrid phase. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2329–2339, 2010     

Water‐based inorganic/polymer hybrid particles prepared via a multiple miniemulsion process

A universal method for the synthesis of water‐based inorganic–polymer hybrid particles was developed in which no organic solvent is required. To demonstrate the versatility of this process, zinc phosphate, calcium carbonate, and barium sulfate were chosen as different pigment examples which additionally can be utilized for functional coating applications. Furthermore, a complex polymeric composition based on epoxy–acrylic–styrene was chosen to illustrate the versatility from a soft matter point of view. The overall synthesis process was carried out by coemulsification of two inverse miniemulsions, containing two precursors, surrounded with a polymerizable continuous phase. This was then transferred to a direct miniemulsion by addition to a surfactant solution and subsequent homogenization followed by radical polymerization of the vinylic monomers. To our knowledge, this is the first work where a polymerizable continuous phase has been used in an inverse miniemulsion formation followed by transfer to a direct miniemulsion, followed by polymerization, so that the result is a water‐based dispersion. The resultant dispersion was characterized by dynamic light scattering; the particles were investigated via transmission electron microscopy with in situ determination of crystallinity using electron diffraction. Elemental analysis was also performed for the particles and the polymerized miniemulsions using X‐ray fluorescence and inductively coupled plasma‐optical emission spectroscopy, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterization of polystyrene‐graphite nanocomposites via surface RAFT‐mediated miniemulsion polymerization

Graphite oxide (GO) was prepared and immobilized with dodecyl isobutyric acid trithiocarbonate (DIBTC) reversible addition‐fragmentation chain transfer (RAFT) agent. The hydroxyl groups of GO were attached to the DIBTC RAFT agent through an esterification process. The resultant modified GO was used for the preparation of polystyrene (PS)/graphite nanocomposites in miniemulsion polymerization. The RAFT‐grafted GO (GO‐DIBTC) at various loadings was dispersed in styrene monomer, and the resultant mixtures were sonicated in the presence of a surfactant (sodium dodecylbenzene sulfonate) and a hydrophobe (hexadecane) to form miniemulsions. The stable miniemulsions thus obtained were polymerized using azobisisobutyronitrile as the initiator to yield encapsulated PS‐GO nanocomposites. The molar mass and polydispersity index of PS in the nanocomposites depended on the amount of RAFT‐grafted GO in the system, in accordance with the features of the RAFT polymerization method. The PS‐GO nanocomposites were of exfoliated morphology, as confirmed by X‐ray diffraction and transmission electron microscopy measurements. The thermal stability and mechanical properties of the PS‐GO nanocomposites were better than those of the neat PS polymer. Furthermore, the mechanical properties were dependent on the modified GO content (i.e., the amount of RAFT‐grafted GO). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of well‐designed polymers carrying saccharide moieties via RAFT miniemulsion polymerization

Two hydrophobic vinyl saccharide monomers based on D ‐glucose and D ‐fructose were polymerized by employing the reversible addition‐fragmentation transfer (RAFT) miniemulsion polymerization technique to prepare well‐designed glycopolymers. Three dithiobenzoate‐RAFT agents [S?C(Ph)S? R], 1‐phenylethyl dithiobenzoate (PED), 2‐phenylprop‐2‐yl dithiobenzoate (PPD), and 2‐cyanoprop‐2‐yl dithiobenzoate (CPD), were used to control the growth of polymer chains. The best results were obtained in the presence of the PPD‐RAFT agent and the formed polymers have polydispersity index's (PDI) lower than 1.15. Under adequate miniemulsion polymerization conditions, a glycopolymer with PDI of 1.1 and molecular weight of 5 × 10⁴ g/mol has been successfully synthesized in a short reaction time of 100 min. Furthermore, some block copolymers containing saccharide segment with butyl or methyl methacrylate were prepared. Copyright © 2007 John Wiley & Sons, Ltd.     

Development of new high transparent hybrid organic–inorganic monoliths with surface engraved diffraction pattern

Flexible hybrid xerogels bringing together high optical transparency up to 96%, low shrinkage down to 5.5%, very smooth surface (average roughness of about 0.3 nm) and thermal stability up to 200 °C were achieved as a result of the optimization of sol‐gel preparative method and a new combination of sol‐gel precursors. Two types of hybrid materials (hereafter referred, respectively, as urea‐silicate and amino‐alcohol‐silicate gels) were synthesized in this work. The shrinkage and the transparency of these materials have been drastically improved by using two different derived siloxanes (3‐isocyanate propyltriethoxysilane and 3‐glycidoxypropyltrimethoxysilane) and two amine‐terminated polyether precursors with different molecular weights. A drying process was implemented to minimize yellowing of prepared samples. Under these conditions, we were able to efficiently reproduce a well‐defined imprinted pattern at materials surface by using an original casting mould. The study of the diffraction characteristics of the obtained grating revealed a good reproducibility of the imprinted grating that shows to be comparable with the original mould. The developed methodology opens the possibility to produce diffraction lenses with a wide range of forms by a simple method based on sol‐gel process. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Synthesis of large,high‐solid‐content latexes by miniemulsion polymerization

Multiple and diverse applications have been recently found for miniemulsions and miniemulsion polymerization. In this work, miniemulsion polymerization is presented as a suitable technique for the preparation of high‐solid‐content latices with large particle sizes. Monomer miniemulsions were prepared with a high‐pressure homogenizer, and droplet sizes of 200–700 nm were obtained. Latexes with particle sizes larger than the sizes commonly accepted for miniemulsion polymerization were obtained. With fixed operational conditions of the homogenizer, the type of stabilizer was the key parameter determining the droplet size and the droplet size distribution. The particle size of the latices obtained by miniemulsion polymerization indicated that the particles were mainly formed by droplet nucleation. Latexes obtained by this process have multiple applications, including use as seeds in the polymerization of high‐solid‐content latices. This article shows that potential new applications for miniemulsion polymerization are far from being exhausted. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4222–4227, 2004     

Synthesis of liquid‐filled nanocapsules via the miniemulsion technique

This study describes the synthesis of well‐defined nanocapsules via the miniemulsion technique. Pentaerythritol tetrakis(3‐mercaptopropionate) (TetraThiol) or 1,6‐hexanediol di(endo, exo‐norborn‐2‐ene‐5‐carboxylate) (DiNorbornene) is used as the oil phase. TetraThiol is encapsulated via the miniemulsion technique without polymerization, as this monomer would simultaneously act as a chain‐transfer agent, and DiNorbornene is encapsulated via miniemulsion polymerization of styrene. Various styrene‐maleic anhydride (PSMA) copolymers and poly(styrene‐maleic anhydride)‐block‐polystyrene (PSMA‐b‐PS) block copolymers were used as surfactant for the synthesis of well‐defined nanocapsules with TetraThiol as the core material. The nanocapsules had a diameter of 150–350 nm and the particle size distribution was narrow. The use of PSMA‐b‐PS block copolymers as surfactant in combination with post‐addition of formaldehyde provided improved stability to the nanocapsules. DiNorbornene was encapsulated via miniemulsion polymerization of styrene, and a stable latex with a bimodal particle size distribution was obtained. The distribution of small particles had a size of 60 nm and the distribution of large particles had a size of 150 nm. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis and optical properties of organic–inorganic hybrid semi‐interpenetrating polymer network gels containing polyfluorenes

Organic–inorganic hybrid semi‐interpenetrating polymer network (semi‐IPN) gels containing polyfluorenes (PFs) are synthesized by hydrosilylation reaction of joint and rod molecules in toluene, where PFs are poly(9,9‐dihexylfluorene‐2,7‐diyl) (PF6) or, poly(9,9‐dioctylfluorene‐2,7‐diyl) (PF8), joint molecules are 1,3,5,7‐tetramethylcyclotetrasiloxane (TMCTS), or 1,3,5,7,9,11,13,15‐octakis(dimethylsilyloxy)pentacyclo‐[9,5,1,1,1,1]octasilsesquioxane (POSS), and rod molecules are 1,5‐hexadiene (HD) or 1,9‐decadiene (DD). The semi‐IPN gels containing low molecular weight PF6 show higher photoluminescence efficiency (?_g) than the toluene solution of PF6L (?_s). The semi‐IPN gels composed of long rod molecule of DD and cubic joint molecule of POSS show the most effective increase in the emission intensity. The emission intensity of PF6L increases as formation of the network in the POSS‐DD semi‐IPN gel. The POSS‐DD semi‐IPN gels containing high molecular weight PF6 and PF8 also show the increase of emission intensity than those of the toluene solutions. The semi‐IPN synthesized in cyclohexane show syneresis and phase separation between network structure and PF chains. The semi‐IPN gels containing PF8 show emission peaks at 450 and 470 nm derived from β‐sheet structure of PF8. A systematic study clears correlation between emission property and network structure and/or composition of semi‐IPN gels. The semi‐IPN gels provide emissive self‐standing soft materials with high efficiency and in a narrow wavelength range emission. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 973–984     

The role of surfactant in controlling particle size and stability in the miniemulsion polymerization of polymeric nanocapsules

The influence of surfactant concentration on particle size and stability of nanocapsules with liquid cores, synthesized by an in situ miniemulsion polymerization process, was investigated. Although the role of surfactant in the synthesis of particles in the nanometer range has frequently been documented, the transition to structured particles, which almost consist of a 1:1 weight ratio of encapsulated liquid hydrophobe to polymeric shell, has not received much attention. Capillary hydrodynamic fractionation (CHDF) analyses were used to evaluate particle size. Results were subsequently used to stoichiometrically calculate the area which is occupied per surfactant molecule on the particle surface. These results were compared with “classical” miniemulsion data, i.e. data generated from the synthesis of polymeric latexes in the presence of a hydrophobe, but at a much lower hydrophobe:monomer ratio as was used here. The surface coverage per surfactant molecule could be related to the surface tension of the latex, thus providing a relationship between particle size and stability. CHDF was furthermore used to investigate particle size after grafting of a secondary PMMA shell. Data obtained from CHDF experiments were in all cases confirmed by TEM analysis of the synthesized particles. To conclude, the synthesis of nanocapsules with liquid cores could be successfully scaled-up, with retention of all the characteristics of the final latex.     

Synthesis,crystal structure solution and characterization of two organic–inorganic hybrid layered materials based on metal sulfates and 1,4‐phenylenediamine

Two organic–inorganic hybrid layered materials, namely poly[(μ‐1,4‐diaminobenzene‐κ²N:N′)[μ₃‐sulfato(VI)‐κ⁴O:O′:O′′,O′′′]manganese], [Mn(SO₄)(C₆H₈N₂)]_n, 1 , and poly[(μ‐1,4‐diaminobenzene‐κ²N:N′)[μ₃‐sulfato(VI)‐κ⁴O:O′:O′′,O′′′]copper], [Cu(SO₄)(C₆H₈N₂)]_n, 2 , have been synthesized using 1,4‐phenylenediamine (PPD) as an organic template and component (linker). Both materials form three‐dimensional frameworks. The crystal structures were determined using data from powder X‐ray diffraction measurements. The purity and morphology of the compounds were studied by elemental analyses and SEM investigations, and their thermal stabilities were determined by thermogravimetric and nonambient powder X‐ray diffraction measurements, which indicated that 1 is stable up to 537 K and 2 is stable up to 437 K.     

Characterization of proton‐conducting organic–inorganic polymeric materials by ASAXS

The distribution of ZrO₂ and phosphotungstic acid (PTA) in a matrix of sulfonated polyether ketone was investigated by anomalous small‐angle X‐ray scattering (ASAXS). Scattering curves were obtained using X‐ray energies near the Zr and W absorption edges, allowing the independent analysis of the distribution of ZrO₂ and PTA in the sample. The interaction between both inorganic components improved their dispersion considerably when compared with films containing just one of the additives. The synergism was correlated to previous investigations concerning proton conductivity and permeability of the membranes developed for direct methanol fuel cell. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2981–2992, 2005     

Isostructural organic–inorganic hybrid compounds: triethylcholine tribromidocadmate and triethylcholine tribromidomercurate

In order to search for new anionic architectures and develop useful organic–inorganic hybrid materials in halometallate systems, two new crystalline organic–inorganic hybrid compounds have been prepared, i.e. catena‐poly[triethyl(2‐hydroxyethyl)azanium [[bromidocadmate(II)]‐di‐μ‐bromido]], {(C₈H₂₀NO)[CdBr₃]}_n, (1), and catena‐poly[triethyl(2‐hydroxyethyl)azanium [[bromidomercurate(II)]‐di‐μ‐bromido]], {(C₈H₂₀NO)[HgBr₃]}_n, (2), and the structures determined by X‐ray diffraction analysis. The compounds are isostructural, crystallizing in the space group P2₁/n. The metal centres are five‐coordinated by bromide anions, giving a slightly distorted trigonal–bipyramidal geometry. The crystal structures consist of one‐dimensional edge‐sharing chains of MBr₅ trigonal bipyramids, between which triethylcholine counter‐cations are intercalated. O—H...Br hydrogen‐bonding interactions are present between the cations and anions.     

Synthesis of sugar‐based macromolecules via sono‐ATRP in miniemulsion

Ultrasound‐mediated atom transfer radical polymerization (sono‐ATRP) in miniemulsion media is used for the first time for the preparation of complex macromolecular architectures by a facile two‐step synthetic route. Initially, esterification reaction of sucrose or lactulose with α‐bromoisobutyryl bromide (BriBBr) is conducted to receive multifunctional ATRP macroinitiators with 8 initiation sites, followed by polymerization of n‐butyl acrylate (BA) forming arms of the star‐like polymers. The brominated lactulose‐based molecule was examined as an ATRP initiator by determining the activation rate constant (k_a) of the catalytic process in the presence of a copper(II) bromide/tris(2‐pyridylmethyl)amine (Cu^IIBr₂/TPMA) catalyst in both organic solvent and for the first time in miniemulsion media, resulting in k_a = (1.03 ± 0.01) × 10⁴ M^?1 s^?1 and k_a = (1.16 ± 0.56) × 10³ M^?1 s^?1, respectively. Star‐like macromolecules with a sucrose or lactulose core and poly(n‐butyl acrylate) (PBA) arms were successfully received using different catalyst concentration. Linear kinetics and a well‐defined structure of synthesized polymers reflected by narrow molecular weight distribution (M_w/M_n = 1.46) indicated 105 ppm wt of catalyst loading as concentration to maintain controlled manner of polymerization process. ¹H NMR analysis confirms the formation of new sugar‐inspired star‐shaped polymers.