Synthesis of polypyrrole nanoparticles in natural rubber–polystyrene blend via emulsion polymerization

Nanoparticles of polypyrrole (PPy) in 40/60 wt % natural rubber (NR)–polystyrene (PS) blends were synthesized by emulsion polymerization using ferric sulfate [Fe₂ (SO₄)₃], sodium dodecyl sulfate (SDS), and n‐amyl alcohol as the oxidant, surfactant, and cosurfactant, respectively. The NR/PS/PPy blends were characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis, thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). FESEM micrographs showed that NR/PS/PPy blends were homogeneous, and PPy nanoparticles were well distributed throughout the binary matrix of NR/PS. The size of PPy particles in the blends was in the range of 26–80 nm. The electrical conductivities of the pellets prepared from NR/PS/PPy blends increased as the composition of PPy nanoparticles was increased, which were in the range of 8.9 × 10^?8 – 2.89 × 10^?4 S/cm. Thermal stability of the blends increased as the content of PPy was increased, as shown by TGA thermograms. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Electroconductive performance of polypyrrole/graphene nanocomposites synthesized through in situ emulsion polymerization

The present study demonstrates a modified in situ emulsion polymerization (EP) approach convenient for the formation of polypyrrole/graphene (PPy/GN) nanocomposites with harnessed conductivities. A series of PPy/GN nanocomposites were prepared by loading different weight percent (wt %) of GN during in situ EP of pyrrole monomer. The polymerization was carried out in the presence of dodecyl benzene sulfonic acid, which acts as an emulsifier and protonating agent. The microstructures of the nanocomposites were studied by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared, X‐ray photoelectron spectroscopy, UV–vis spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and thermogravimetric analyses. The electrical conductivities of the nanocomposite pellets pressed at different applied pressures were determined using four probe analyzer. The electrical conductivities of the nanocomposites were considerably enhanced as compared to those of the individual PPy samples pressed at the same pressures. An enhanced conductivity of 717.06 S m^?1 was observed in the sample with 5 wt % GN loading and applied pressure of 8 tons. The results of the present study signify that the addition of GN in the PPy polymer harnesses both electrical and thermal properties of the polymer. Thus, PPy/GN nanocomposites with superior properties for various semiconductor applications can be obtained through direct loading of GN during the polymerization process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41800.     

Heterocoagulation behavior of carbon black with surface encapsulation through emulsion polymerization

Nanocomposite microspheres containing styrene–acrylate resin, wax, and carbon black (CB) with desired CB dispersion were prepared through heterocoagulation. The CB surface was modified using conventional anionic emulsifier and anionic dispersants with different lengths of nonionic chains and reactivities or through polymer encapsulation via emulsion polymerization to regulate the dispersion and concentration of CB in the microspheres. Experimental results showed that anionic dispersants with long nonionic chains effectively dispersed and stabilized CB particles. Polystyrene (PS) was then encapsulated on the CB surface by using a reactive dispersant and a water‐soluble initiator of polymerization. The CB particles exhibited comparable pH stability with other heterocoagulation components. Overall, encapsulation through emulsion polymerization can be used to obtain not only high CB content but also improved CB distribution in the resulting microspheres. High coagulation efficiency can also be achieved using polystyrene‐encapsulated dispersed CB because of its high affinity to emulsifiers and reactive dispersants during dispersion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43516.     

Nano‐SiO2/PMMA‐PU composite particles with core‐shell structure via emulsion polymerization and their application in epoxy resin

A novel method of nano‐SiO₂/poly(methyl methacrylate)(PMMA)‐polyurethane(PU) composite particles modifying epoxy resin is reported. The composite particles with the obvious core‐shell structure were prepared by emulsion polymerization of PMMA and PU prepolymer on the surface of nano‐SiO₂. The diameter of the composite particles was 50–100 nm with dark core SiO₂ (30–60 nm) and light shell polymer of PMMA and PU (20–30 nm); moreover, PU was well distributed in PMMA with about 10 nm diameter. After nano‐SiO₂ was encapsulated by PMMA and PU, the Si content on the surface decreased rapidly to 2.08% and the N content introduced by PU was about 1.27%. The ratio of polymer to original nano‐SiO₂ (f_p), the grafting ratio of polymer to original nano‐SiO₂ (f_r) and the efficiency grafting ratio of polymer (f_e) were, respectively, about 116.7%, 104.4%, and 89.5%. The as‐prepared composite particles were an effective toughness agent to modify epoxy resin, and the impact strength of the modified epoxy resin increased to 46.64 kJ m^?2 from 19.12 kJ m^?2 of the neat epoxy resin. This research may enrich the field of inorganic nanoparticles with important advances toward the modification for polymer composite materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41919.     

Morphology controlled synthesis of polyaniline nanostructures using swollen liquid crystal templates

Preparation of zero‐dimensional and one‐dimensional nanostructures of polyaniline (PANI) were achieved by using swollen liquid crystals (SLCs) as ‘soft' templates. The monomer (aniline) was first entrapped in SLCs by replacing the oil phase (cyclohexane) with a mixture of aniline and cyclohexane. Zero‐dimensional nanostructures of PANI were obtained by thorough mixing of APS with the mesophases. One‐dimensional nanostructures were prepared by allowing slow diffusion of APS through the mesophase. PANI nanostructures were extracted from the mesophase and were characterized by UV‐visible spectroscopy, FTIR spectroscopy, powder X‐ray diffraction, atomic force microscopy, scanning electron microscopy (SEM), and conductivity measurements. A plausible mechanism for the formation of the nanostructures has been proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40800.     

Synthesis of polydiphenylamine with tunable size and shape via emulsion polymerization

The emulsion polymerization process was used in the synthesis of polydiphenylamine (PDPA) to obtain new morphologies, and the effects of surfactant types ? anionic, cationic, non‐ionic ? and surfactant concentrations were investigated with the roles of a template and a dopant. Scanning electron microscopy images indicated different PDPA morphologies depending on the surfactant type. The new morphological structures of the obtained PDPA were leaf‐like, coral‐reef‐like and red‐blood‐cell‐like, which have not been synthesized or seen before. The agglomeration of each nanoparticle is in the range of 50 nm to 500 nm depending on the surfactant type. The structure characterizations carried out by Fourier transform infrared spectroscopy, X‐ray diffractometry and UV?visible spectroscopy confirm the incorporation of surfactant in the PDPA. The electrical conductivity values of the PDPA with surfactants are higher than that without a surfactant by four orders of magnitude and are consistent with the resultant smaller particle sizes and narrower optical band gap as calculated from UV?visible data. To induce higher electrical conductivity of PDPA, various dopants were used. However, the thermal stability of the PDPA is lower than that of conventional microscopic PDPA (cPDPA) due to the larger surface area of PDPA which can decompose more easily. © 2014 Society of Chemical Industry     

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     

Preparation of conducting composites of polypyrrole using supercritical carbon dioxide

Supercritical carbon dioxide, saturated with pyrrole, was brought into contact with oxidant‐impregnated films of poly(chlorotrifluoroethylene) (PCTFE), crosslinked poly(dimethylsiloxane) (PDMS), poly(methyl methacrylate) (PMMA), and porous crosslinked polystyrene (PS) in order to form conducting composites via the in situ polymerization of pyrrole. The two nonporous hosts—PCTFE and crosslinked PDMS—did not form conducting composites with polypyrrole (PPy). On the other hand, the electrical conductivity of the PPy composites with carbon dioxide‐swollen PMMA and porous PS ranged from 1.0 × 10^?4 S/cm to 3.0 × 10^?5 S/cm. In these two cases, the level of pyrrole polymerized on the surface or in the pores of the host polymer was sufficient to attain the interconnected conducting polymer networks necessary for electrical conductivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1113–1116, 2003     

Didecyl ester of 4‐sulfophthalic acid as a plast dopant and emulsifier in the chemical polymerization of aniline into polyaniline salt

Polyaniline salt was synthesized through the chemical oxidation of aniline with sodium persulfate as the oxidant and didecyl ester of 4‐sulfophthalic acid via three different polymerization pathways (aqueous, emulsion, and interfacial). In these polymerization processes, the ester acted as a novel plast dopant and as an emulsifier. The yield, conductivity, and number of ester units present in the polyaniline salts were determined. A polyaniline salt prepared by emulsion polymerization was soluble in chloroform and showed excellent solution‐processing properties. Polyaniline samples prepared by aqueous or interfacial polymerization were not soluble in chloroform. A soluble polyaniline salt was successfully synthesized through the washing of an organic layer containing the polyaniline salt with water in emulsion polymerization. X‐ray diffraction spectra of polyaniline salts prepared by the three different methods showed an ordered, layer‐type supramolecular structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of poly(butyl acrylate)‐poly(methyl methacrylate) core–shell nanomaterials of anti‐crease‐whitening properties

Core–shell nanomaterials of poly(butyl acrylate)‐poly(methyl methacrylate) were synthesized using a differential microemulsion polymerization method for being used as polyacrylate‐based optical materials, which meet the requirement of anti‐crease‐whitening and proper mechanical strength. The effects of reaction temperature and surfactant amount on the particle sizes, as well as the effect of reaction temperature on the conversion and solid content were investigated to reveal the dependence of the application properties on the reaction conditions. The spherical morphology of core–shell nanoparticles was also studied via transmission electron microscopy. The resulting polymers with a core–shell monomer ratio of butyl acrylate/methyl methacrylate at 32/10 (vol/vol) demonstrated the optimal balanced properties in the anti‐crease‐whitening and mechanical property, confirmed by the visible light transmittance measurement and the dynamic analysis of the viscoelastic properties of the synthesized core–shell nanomaterials. The smaller the particle size, the better the transparency of the resulting polymer films. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39991.     

Controllable fabrication of micro/nanostructures by electrospinning from polystyrene/poly(vinyl alcohol) emulsion dispersions

In this article, controllable micro/nanostructures were successfully obtained by electrospinning with the emulsion dispersions of polystyrene and poly(vinyl alcohol) (PS/PVA). The micro/nanostructure of electrospun PS/PVA emulsion dispersions such as corn‐like, spindle‐like, and bowl‐like (or bracelet‐like) were precisely controlled by regulating the electrospun parameters including the surfactant, the applied voltages, and the compositions of PS/PVA emulsion dispersions. The non‐ionic surfactant (Poloxamer) was crucial for the stability of the PS/PVA emulsion dispersions although the surfactant in PS/PVA emulsion was in tiny amount. The high applied voltages were beneficial for the forming the “lined‐fiber” structure but not for spheroids structure (bracelet‐like structure). Moreover, the increasing content of PS in PS/PVA emulsion resulted in more spheroid structure than the “lined‐fiber.” This work was meaningful for the forming mechanism of micro/nanostructure in emulsion electrospinning and made a potential contribution for controllable fabrication of micro/nanostructure of the electrospun PS/PVA emulsion dispersions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46288.     

Inverted emulsion polymerization route to polyaniline‐3D nanofiber network using sulfonated‐p‐cresol as novel dopant

Sulfonated‐p‐cresol (SPC) was used as novel dopant for the first time in the synthesis of polyaniline in 3D nanofiber networks (PANI‐3D). Polyaniline in 3D nanofiber network was prepared using organic solvent soluble benzoyl peroxide as oxidizing agent in presence of SPC and sodium lauryl sulfate (SLS) surfactant via inverted emulsion polymerization pathway. The influence of synthesis conditions such as the concentration of the reactants, stirring/static condition, and temperature etc., on the properties and formation of polyaniline nanofiber network were investigated. Polyaniline in 3D nanofiber network with 40–160 nm (diameter), high yield (134 wt % with respect to aniline used), and reasonably good conductivity (0.1 S/cm) was obtained in 24 h time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Monodispersed composite particles prepared via emulsifier‐free emulsion polymerization using waterborne polyurethane as microreactors

Monodispersed polystyrene particles in submicrometer size were intriguingly prepared through emulsifier‐free batch‐seeded emulsion polymerization using nonmonodispersed waterborne polyurethane (WBPU) beads as microreactors. Different feed ratios of styrene (St)/WBPU for the preparation of composite particles were investigated, and the size–growth course was experimentally followed. The morphology and dispersity of the particles were characterized by scanning electron microscopy together with dynamic laser scattering particle size analyzer. Their inside structure was further characterized by transmission electron microscopy with ultramicrotomy combined with X‐ray photoelectron spectroscopy for the composite particles' surface analysis. The probable grafting polymerization of St from WBPU was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance instrument. The obtained composite particles were again employed as the seeds in the emulsion copolymerization of methyl methacrylate. As a result, the formed multilayered composite particles with reverse core–shell structure were also monodispersed and spherical. The mechanism of the formation of the monodispersed particles was proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40985.     

On-line control of emulsion polymerization reactors: A perspective

Emulsion polymerization is the method of choice to produce a wide range of specialty waterborne polymer dispersions. These are multicharacteristic products that should meet conflicting application properties and are produced through a very complex process prone to suffer run-to-run irreproducibilities. In a scenario of increasing competition and smaller margins, achieving even more efficient production of better materials in a consistent, cost effective, safe, and environmentally friendly way will only be possible by implementing on-line control. However, on-line control is hindered by the lack of sensors able to monitor most of the characteristics of the emulsion polymers. This perspective discusses the state-of-the-art of the on-line control of emulsion polymerization reactors highlighting the achievements, challenges, and opportunities.     

Emulsifier‐free emulsion polymerization of acrylonitrile in the presence of poly(methyl methacrylate) seed particles: Influence of the addition mode on the surface morphology

Acrylonitrile (AN) was polymerized in the presence of poly(methyl methacrylate) (PMMA) seed latex by both the batch and dropwise addition modes. The two addition modes both led to PMMA/polyacrylonitrile (PAN) composite particles with a core/shell structure with PMMA as the core and PAN as the shell. The shell thickness could be adjusted by a change in the amount of the second‐stage AN monomer relative to the PMMA seed polymer. However, the surface morphologies of the composite polymers were quite different, which showed a rambutan‐like batch mode and an urchinlike dropwise mode. The reason was considered as the different precipitation mechanisms of PAN small‐particle precipitation for the batch mode and linear PAN segment growth for the dropwise mode. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and EMI shielding studies of polyaniline grafted conducting nanohybrid

Polyaniline (PANI) grafted conducting nanohybrids are successfully synthesized by emulsion graft polymerization. Maximum grafting of 644% is obtained on sepiolite at optimized concentrations and reaction conditions. The Fourier transform infrared (FT-IR) spectra of sepiolite grafted polyaniline (MS-g-PANI) nanohybrid revealed the presence of stretching vibrations of C=C bonds of polyaniline at 1580 and 1490 cm⁻¹ along with the characteristic peaks of sepiolite. Increased thermal stability of the nanohybrid is observed with the increase in polyaniline grafting. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to study the structural changes caused by grafting. A progressive increase in electrical conductivity is observed with the increase in grafting yield. Maximum electrical conductivity of 0.427 Scm⁻¹ is observed in the nanohybrid having 644% grafting. 24.2 dB (>99% attenuation) EMI shielding effectiveness has been exhibited by the developed nanohybrids in X-band frequency range.     

Synthesis of hybrid polyaniline/carbon nanotubes nanocomposites in toluene by dynamic interfacial inverse emulsion polymerization under sonication

This work describes an empirical study of in situ interfacial dynamic inverse emulsion polymerization process under sonication of aniline in the presence of nine different types of carbon nanotubes (CNT) in toluene. The polymerization method described in this work is simple and very fast (5 min) compared to the other literature reports (3–12 h). During polymerization, CNT are coated with polyaniline (PANI) forming a core‐shell structure of nanowires as evidenced by transmission electron microscopy (TEM) and high‐resolution scanning microscopy (HRSEM). HRSEM images and surface resistivity imply that PANI coating of CNT leads to a remarkable improvement in separation and dispersion of CNT in toluene, which otherwise would have rapidly coagulate and settle. Two of the nine different CNT studied have shown the lowest surface resistivities. Films of uniform thickness were successfully produced (HRSEM of cross‐sections). The effect of film thickness on conductivity and optical properties is reported in the work. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Morphology,structure, and conductivity of polypyrrole prepared in the presence of mixed surfactants in aqueous solutions

Polypyrrole (PPy) was prepared from different mixed‐surfactant solutions with ammonium persulfate as an oxidant. Three types of combinations were selected, including cationic/anionic, cationic/nonionic, and anionic/nonionic mixed‐surfactant solutions. The surfactants used in the experiments included cetyltrimethylammonium bromide (cationic surfactant), sodium dodecyl sulfate (anionic surfactant), sodium dodecyl sulfonic acid salt (anionic surfactant), poly(vinyl pyrrolidone) (nonionic surfactant), and poly(ethylene glycol) (nonionic surfactant). The morphology, structure, and conductivity of the resulting PPy were investigated in detail with scanning electron microscopy, Fourier transform infrared spectra, and the typical four‐probe method, respectively. The results showed that the interaction between the different surfactants and the interaction between the surfactants and the polymer influenced the morphology, structure, and conductivity of the resulting polymer to different degrees. The cationic surfactant favored the formation of nanofibers, the addition of anionic surfactants produced agglomeration but enhanced the doping level and conductivity, and the presence of a nonionic surfactant weakened the interaction between the other surfactant and the polymer in the system. In comparison with the results for monosurfactant solutions, the polymerization of pyrrole in mixed‐surfactant solutions could modulate the morphologies of PPy, which ranged from nanofibers of different lengths to nanoparticles showing various states of aggregation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1987–1996, 2007     

Multi‐responsive microgel of a water‐soluble monomer via emulsion polymerization

Microgel of a water‐soluble monomer [2‐(N‐morpholino)ethyl methacrylate (MEMA)] was successfully prepared in aqueous media via emulsion polymerization by using a novel water‐soluble block copolymer as stabilizer. Characterization studies confirmed monodisperse spherical morphologies of microgels with a diameter of 280 nm at neutral pH. These microgels exhibited multi‐responsive behavior by responding solution pH, temperature, ionic strength, type of dispersing media, and magnetic particles. It swells well at low pH (<6.0) and at low temperature, but shrinks above pH 6.0, or even more shrinks with salt addition at neutral and basic conditions. In addition, the hydrodynamic diameter of PMEMA microgel was decreased gradually at basic and neutral pH when solution temperature was increased up to the lower critical solution temperature of PMEMA (LCST, 35°C), but microgel diameter did not change much above LCST. Multi‐responsive behavior of PMEMA microgel was investigated by using dynamic light scattering, UV‐Vis spectrophotometer and zeta potentiometer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42072.     

Facile preparation of poly(3,4‐ethylenedioxythiophene) nanoparticles via a miniemulsion polymerization process

Poly(3,4‐ethylenedioxythiophene) (PEDOT) nanoparticles were prepared via a miniemulsion polymerization process. The chemical oxidative polymerization of 3,4‐ethylenedioxythiophene (EDOT) occurred in the presence of β‐1,3‐glucan with the injection of an aqueous oxidant solution, and the nanodroplets of EDOT were transformed to PEDOT nanoparticles dispersed in the aqueous medium. The aqueous emulsion of PEDOT nanoparticles showed relatively long emulsion stability (> 8 weeks), and the recovered solid nanoparticles were also redispersible in deionized water without deposition. The size and size distribution of PEDOT nanoparticles could be controlled by adjusting the operating conditions of the ultrasonifier before the polymerization process. The building‐up of a shearing force decreases the size of the PEDOT nanoparticles and also causes the occurrence of a multimodal size distribution for the PEDOT nanoparticles. The electrical conductivity of the PEDOT nanoparticles was 0.28–1.20 S cm⁻¹. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011