Investigation of optical and thermally stimulated properties of SiO2 nanoparticles‐filled polycarbonate

Polycarbonate nanocomposite containing silicon oxide nanoparticles average size of 5 nm at different weight ratio has been prepared by solution mixing method. The dispersion of nanoparticles in polymer matrix was studied by transmission electron microscopy (TEM). The optical and thermally stimulated behavior of nanocomposites were analyzed by energy dispersive X‐ray spectra (EDX), X‐ray diffraction pattern (XRD), UV–vis spectroscopy, differential scanning calorimetry (DSC), and thermally stimulated discharge current (TSDC). TEM images show the dispersion and size of the nanoparticles, however, EDX indicate the presence of SiO₂ on the surface of the nanocomposite film. An XRD result reveals that the crystallinity increases with increase in concentration of SiO₂ nanoparticles in polymer matrix. The direct and indirect optical energy band gaps decreased and number of carbon atom increased with concentration of SiO₂ nanoparticles. We have observed that the increase of SiO₂ nanoparticles in PC significantly reduces the refractive index. DSC and TSDC show that glass transition temperature increases according to SiO₂ weight ratio. The TSDC of nanocomposites samples could be understand in terms of non‐Debye theory of charge relaxation and co‐tunneling mechanism of charge transport. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Facile synthesis,characterization and material properties of a novel poly(vinyl cinnamate)/ nickel oxide nanocomposite

A poly(vinyl cinnamate) (PVCin) composite was synthesized by a simple one step in situ polymerization of vinyl cinnamate with nickel oxide (NiO) nanoparticles. The structural, morphological and thermal properties of the nanocomposite were characterized using Fourier transform (FT)‐Raman, FT infrared (FTIR) and UV spectroscopies, X‐ray diffraction (XRD), high‐resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), differential scanning calorimetry and vibrating sample magnetometry (VSM) measurements. FT‐Raman, FTIR and UV spectroscopy results revealed the characteristic absorption and shifts of peaks of the polymer matrix, the shifts being attributed to the interaction of NiO nanoparticles with the polymer chains. The structural and morphological analysis using XRD, HRTEM and FESEM showed the uniform arrangement of nanoparticles within the polymer chains. VSM showed the ferromagnetic nature of the composite with an increasing saturation of magnetism. The glass transition temperature (T_g) of the composite was higher than that of pure PVCin and T_g of the composite increased with increasing nanoparticle content. The electrical resistivity of the nanocomposite was studied from AC and DC conductivity measurements. AC and dielectric properties were markedly enhanced in the whole range of frequency due to the presence of NiO nanoparticles. DC conductivity of the nanocomposite was much higher than that of PVCin and the conductivity of the nanocomposite increased with increasing content of NiO nanoparticles. © 2016 Society of Chemical Industry     

Synthesis of copper–polystyrene nanocomposite particles using water in supercritical carbon dioxide medium and its antimicrobial activity

Copper‐encapsulated polystyrene nanocomposite particles were prepared through ex situ dispersion of Cu nanoparticles into monomer droplets and subsequent polymerization using water in supercritical carbon dioxide (water‐in‐sc‐CO₂) at 70°C. First, colloidal dispersion of copper nanoparticles was synthesized by chemical reduction of copper chloride (CuCl₂) using sodium borohydrate (NaBH₄) as reducing agent. Colloidal dispersion of copper nanoparticles was added slowly during the polymerization of styrene using water‐in‐sc‐CO₂ medium at 70°C and 20.68 MPa. Cu nanoparticle encapsulated polymer particles were characterized by UV, X‐ray diffraction, thermogravimetric analysis, SEM, and TEM. Cu nanoparticles were uniformly distributed inside the polymer matrix during the polymerization process. This work represents a simple way to prepare a variety of metal nanoparticles encapsulated polymer particles using water‐in‐sc‐CO₂ medium. The Cu/polystyrene nanocomposite particles exhibit antimicrobial activity against a number of bacteria. The current work represents a simple, cheap and universal way to prepare a variety of metal–polymer nanocomposite materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of poly(methyl methacrylate)‐Silica nanoparticles via differential microemulsion polymerization and physical properties of NR/PMMA‐SiO2 hybrid membranes

Poly(methy methacrylate) (PMMA)‐SiO₂ nanoparticles were prepared via differential microemulsion polymerization. The effects of silica loading, surfactant concentration, and initiator concentration on monomer conversion, particle size, particle size distribution, grafting efficiency, and silica encapsulation efficiency were investigated. A high monomer conversion of 99.9% and PMMA‐SiO₂ nanoparticles with a size range of 30 to 50 nm were obtained at a low surfactant concentration of 5.34 wt% based on monomer. PMMA‐SiO₂ nanoparticles showed spherical particles with a core‐shell morphology by TEM micrographs. A nanocomposite membrane from natural rubber (NR) and PMMA‐SiO₂ emulsion was studied for mechanical and thermal properties and pervaporation of water‐ethanol mixtures. PMMA‐SiO₂ nanoparticles which were uniformly dispersed in NR matrix, significantly enhanced mechanical properties and showed high water selectivity in permeate flux. Thus, the NR/PMMA‐SiO₂ hybrid membranes have great potential for pervaporation process in membrane applications. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers     

Improvement of interfacial interaction,dispersion, and properties of chlorosulfonated polyethylene/sio2 nanocomposites using CSPE‐g‐Sio2 nanoparticles synthesized under ultrasonics

Chlorosulfonated polyethylene (CSPE) is a widely used elastomer because of the resistance to gases and aggressive chemicals, fire‐retarding, and electric insulating properties. Silica nanoparticles were usually introduced into the elastomer to improve its critical properties. However, there were some problems of strong aggregation and poor dispersion of nanoparticles in the nanocomposites. In this work, an efficient approach of grafting matrix CSPE onto silica surface was proposed to solve the problems. CPSE‐g‐SiO₂ nanoparticles were prepared via an in situ radical reaction between  Cl in CSPE and Si OH on silica surface under ultrasonics. The successful chemical graft reaction was confirmed using Fourier transform infrared, ultraviolet–visible spectroscopy, ¹H‐NMR, and X‐ray photoelectron spectroscopy. Thermogravimetric analysis indicated that the grafting amount of CSPE was 4.68 wt%. Grafting CSPE onto silica surface significantly improved the dispersion of CSPE‐g‐SiO₂ nanoparticles in CSPE matrix and the interfacial interaction. Therefore, the mechanical, thermal stability, damping capacity, and rheology properties of CSPE/CSPE‐g‐SiO₂ nanocomposites were improved. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Viscoelastic behavior of poly(butyl methacrylate) densely grafted on silica nanoparticles

A series of poly(butyl methacrylate)s (PBMAs) with various molar masses (33 000–270 000 g mol^?1), which were densely grafted on fumed silica nanoparticles (PBMA–SiO₂), were synthesized by surface‐initiated atom transfer radical polymerization. The dynamic viscoelastic behavior of PBMA–SiO₂ was systematically investigated in the solid and molten states with oscillatory strains, and compared to that of a conventional nanocomposite (PBMA/SiO₂). The storage moduli of PBMA–SiO₂ and PBMA/SiO₂ are equivalent in the solid state, whereas the storage modulus of PBMA–SiO₂ is lower than that of PBMA/SiO₂ in the molten state, especially at high silica loading. This is because the formation of a network structure composed of the silica nanoparticles in PBMA–SiO₂ is strongly suppressed by the polymer brushes on the particles. In contrast, even at low silica loading, the PBMA–SiO₂ system exhibits a gel‐like behavior resulting from a steric repulsion between the composite particles, because all of the tethered polymers behave as bound polymers. Copyright © 2011 Society of Chemical Industry     

Fumed SiO2 nanoparticle reinforced biopolymer blend nanocomposites with high dielectric constant and low dielectric loss for flexible organic electronics

In the present study, fumed silica (SiO₂) nanoparticle reinforced poly(vinyl alcohol) (PVA) and poly(vinylpyrrolidone) (PVP) blend nanocomposite films were prepared via a simple solution‐blending technique. Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to elucidate the successful incorporation of SiO₂ nanoparticles in the PVA/PVP blend matrix. A thermogravimetric analyzer was used to evaluate the thermal stability of the nanocomposites. The dielectric properties such as dielectric constant (?) and dielectric loss (tan δ) of the PVA/PVP/SiO₂ nanocomposite films were evaluated in the broadband frequency range of 10^?2 Hz to 20 MHz and for temperatures in the range 40–150 °C. The FTIR and UV–vis spectroscopy results implied the presence of hydrogen bonding interaction between SiO₂ and the PVA/PVP blend matrix. The XRD and SEM results revealed that SiO₂ nanoparticles were uniformly dispersed in the PVA/PVP blend matrix. The dielectric property analysis revealed that the dielectric constant values of the nanocomposites are higher than those of PVA/PVP blends. The maximum dielectric constant and the dielectric loss were 125 (10^?2 Hz, 150 °C) and 1.1 (10^?2 Hz, 70 °C), respectively, for PVA/PVP/SiO₂ nanocomposites with 25 wt % SiO₂ content. These results enable the preparation of dielectric nanocomposites using a facile solution‐casting method that exhibit the desirable dielectric performance for flexible organic electronics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44427.     

Synthesis and characterization of core‐shell SiO2 nanoparticles/poly(3‐aminophenylboronic acid) composites

SiO₂/Poly(3‐aminophenylboronic acid) (PAPBA) composites were synthesized under different experimental conditions, using ultrasonic irradiation method. Polymerization was carried out in the presence of sodium fluoride and D ‐fructose to anchor 3‐aminophenylboronic acid groups on to SiO₂ surface. The SiO₂/PAPBA nanocomposite prepared by NaF and D ‐fructose in the polymerization medium was found to show different morphology, electrical properties, thermal behavior and structural characterization in comparison to the nanocomposites prepared under other conditions. Ultrasonic irradiation minimizes the aggregation of nanosilica and promotes anchoring of PAPBA units over SiO₂ surface. The morphology of PAPBA/ SiO₂ nanocomposite was investigated by using transmission electron microscopy, UV‐visible spectroscopy; thermogravimetric analysis, Fourier transform infrared spectroscopy, and X‐ray diffraction analysis were used for characterization. Transmission electron microscope of the nanocomposites observation shows that SiO₂/PAPBA composite, prepared with D ‐fructose and NaF under ultrasonication has a core–shell morphology. The thermal and crystalline properties of core‐shell SiO₂/PAPBA nanocomposite was prepared via ultrasonication method is different from the SiO₂/PAPBA nanocomposite prepared via conventional stirring method, in which SiO₂ nanoparticles are submerged in PAPBA. Conductivity of the composite prepared via ultrasonication shows around 0.2 S/cm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2743–2750, 2007     

Liquid‐phase hydrogenation of cinnamaldehyde over Cu‐Au/SiO2 catalysts

The synthesis, characterization, and application of silica‐supported Cu‐Au bimetallic catalysts in selective hydrogenation of cinnamaldehyde are described. The results showed that Cu‐Au/SiO₂ bimetallic catalysts were superior to monometallic Cu/SiO₂ and Au/SiO₂ catalysts under identical conditions. Adding a small amount of gold (6Cu‐1.4Au/SiO₂ catalyst) afforded eightfold higher catalytic reaction rate compared to Cu/SiO₂ along with the high selectivity (53%, at 55% of conversion) toward cinnamyl alcohol. Characterization techniques such as x‐ray diffraction, H₂ temperature‐programmed reduction, ultraviolet‐visible spectroscopy, transmission electron microscopy, Fourier‐transform infrared spectra of chemisorbed CO, and x‐ray photoelectron spectroscopy were employed to understand the origin of the catalytic activity. A key genesis of the high activity of the Cu‐Au/SiO₂ catalyst was ascribed to the synergistic effect of Cu and Au species: the Au sites were responsible for the dissociative activation of H₂ molecules, and Cu⁰ and Cu⁺ sites contributed to the adsorption‐activation of C?C and C?O bond, respectively. A combined tuning of particle dispersion and its surface electronic structure was shown as a consequence of the formation of Au‐Cu alloy nanoparticles, which led to the significantly enhanced synergy. A plausible reaction pathway was proposed based on our results and the literature. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3300–3311, 2014     

Facile preparation of superhydrophobic polyester surfaces with fluoropolymer/SiO2 nanocomposites based on vinyl nanosilica hydrosols

A facile method to prepare superhydrophobic fluoropolymer/SiO₂ nanocomposites coating on polyester (PET) fabrics was presented. The vinyl nanosilica (V? SiO₂) hydrosols were prepared via one‐step water‐based sol‐gel reaction with vinyl trimethoxy silane as the precursors in the presence of the base catalyst and composite surfactant. Based on the V? SiO₂ hydrosol, a fluorinated acrylic polymer/silica (FAP/SiO₂) nanocomposite was prepared by emulsion polymerization. The FAP/SiO₂ nanocomposites were coated onto the polyester fabrics by one‐step process to achieve superhydrophobic surfaces. The results showed that silica nanoparticles were successfully incorporated into the FAP/SiO₂ nanocomposites, and a specific surface topography and a low surface free energy were simultaneously introduced onto PET fibers. The prepared PET fabric showed excellent superhydrophobicity with a water contact angle of 151.5° for a 5 μL water droplet and a water shedding angle of 12° for a 15 μL. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40340.     

Polyimide‐silica nanocomposites exhibiting low thermal expansion coefficient and water absorption from surface‐modified silica

In this study, a commercially available nano‐sized silica (SiO₂) was surface‐modified via esterification with oleic acid (OA), a relatively inexpensive and hydrophobic modifier, and characterized by FTIR, NMR, SEM, EDS, and TGA measurements. Various amounts of the surface‐modified silica nanoparticles (SiO₂‐OA) were dispersed in a poly(amic acid), which were then cyclized at high temperatures to form a series of PI/SiO₂‐OA nanocomposite films (PISA). The effect of the addition of the SiO₂‐OA nanoparticles on the properties of the as‐prepared polyimide nanocomposite was studied. The results indicated that, comparing with pure PI and PI/pristine‐SiO₂ composite film (PISI), the as‐prepared PISA films had enhanced dynamic mechanical properties and thermal stability, as well as reduced water absorption and thermal expansion. The as‐prepared PI/SiO₂‐OA nanocomposites have potential for applications in high performance microelectronic devices. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 4096–4105, 2007     

Preparation of poly(acrylamide‐co‐acrylic acid)/silica nanocomposite microspheres and their performance as a plugging material for deep profile control

In this work, poly(acrylamide‐co‐acrylic acid)/silica [poly(AM‐co‐AA)/SiO₂] microspheres were prepared by inverse phase suspension polymerization in the presence of γ‐3‐(trimethoxysilyl) propyl methacrylate (or 3‐methacryloxypropyltrimethoxysilane) modified SiO₂. The effects of SiO₂ nanoparticles on tuning morphology and properties of the nanocomposite microspheres were studied. Plugging ability and oil displacement performance were also systematically investigated by single‐ and double‐tube sand pack models. The results showed that SiO₂ nanoparticles can effectively adjust surface smoothness, swelling behavior, and thermal stability of the nanocomposite microspheres. Compared with pure copolymer microspheres, these nanocomposite microspheres also displayed better salt tolerance and shear resistance. Such multifunctional nanocomposite microspheres can provide effective plugging in the high‐permeability channels and can also achieve deep profile control. The highest plugging rate can be 86.11% and the oil recovery for low‐permeability tube was enhanced by 19.69%. This research will provide a candidate material for the further enhanced oil recovery (EOR) research and supply the theoretical support for profile control system in field application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45502.     

A convenient approach to synthesize stable silver nanoparticles and silver/polystyrene nanocomposite particles

In this study, silver nanoparticles were prepared by the reduction of silver nitrate in SDS+ isopentanol/styrene/H₂O reverse microemulsion system using sodium citrate as reducing agent. The Ag/PS nanocomposite particles were prepared by in situ emulsion polymerization of the styrene system containing silver nanoparticles that did not separate from the reaction solution. The polymerization dynamic characteristic was studied, at the same time, silver nanparticles and the encapsulation of composite particles were characterized by Fourier‐transform‐infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X‐ray diffraction (XRD) measurement, UV–vis diffuse reflectance spectroscopy, and X‐ray photoelectron spectroscopy (XPS). The results of TEM and UV–vis absorption spectra showed that well‐dispersed silver nanoparticles have a narrow size distribution. XRD showed that Ag and Ag/PS nanocomposite particles were less than 10 and 20 nm in size, which is similar to those observed by TEM. The results of XPS spectra revealed that the microemulsion system can stabilize the silver nanoparticles from aggregation and provided supporting evidence for the polystyrene encapsulated silver nanoparticle structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Crystallization of poly(ethylene oxide) embedded with surface‐modified SiO2 nanoparticles

The crystallization of poly(ethylene oxide) (PEO) in the presence of silica nanoparticles (SiO₂ NPs) was investigated in terms of heterogeneous nucleation of SiO₂ NPs using polarizing optical microscopy and differential scanning calorimetry. The content and surface functionality of SiO₂ NPs were considered as the main factors affecting crystallization, and the effect of annealing time and temperature was also examined. The SiO₂ NPs acted as heterogeneous nucleates during the crystallization process, thereby enhancing the nucleation density and limiting the spherulitic growth rate. A kinetics study of non‐isothermal crystallization showed that the crystallization rate of 5 wt% SiO₂/PEO nanocomposite was ca 2.1 times higher than that of neat PEO. In addition, among various surface‐functionalized SiO₂ nanoparticles, alkyl‐chain‐functionalized SiO₂ NPs were favorable for achieving a higher crystallization rate due to the enhanced compatibility between the SiO₂ NPs and PEO chains. © 2012 Society of Chemical Industry     

Mechanochemical modification of silica with poly(1‐vinyl‐2‐pyrrolidone) by grinding in a stirred media mill

The polymerization of 1‐vinyl‐2‐pyrrolidone (VP) mechanochemically initiated by grinding silica was investigated in a wet stirred media mill. The polymerization itself proceeds from the silica grinding without any additional initiator. We have found that the amount of grafted polymer increases with an increase in total ground silica surface. The suspension of polymer‐modified silica nanoparticles showed high colloidal stability in water because of the appearance of grafted hydrophilic PVP on the surface during the reactive grinding. Because the nanoparticles SiO₂‐graft‐PVP are biocompatible, the developed polymer nanocomposite material can be of particular interest for the performance of membranes and for the fabrication of biocompatible hydrogels with enhanced mechanical properties and porosity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3708–3714, 2007     

Silica/polystyrene and silica/polystyrene‐b‐polymethacryloxypropyltrimethoxysilane hybrid nanoparticles via surface‐initiated ATRP and comparison of their wettabilities

Both silica/polystyrene (SiO₂/PS) and silica/polystyrene‐b‐polymethacryloxypropyltrimethoxysilane (SiO₂/PS‐b‐PMPTS) hybrid nanoparticles were synthesized via surface‐initiated atom transfer radical polymerization (SI‐ATRP) from SiO₂ nanoparticles. The growths of all polymers via ATRP from the SiO₂ surfaces were well controlled as demonstrated by the macromolecular characteristics of the grafted chains. Their wettabilities were measured and compared by water contact angle (WCA) and surface roughness. The results show that the nanoparticles possess hydrophobic surface properties. The static WCA of SiO₂/PS‐b‐PMPTS hybrid nanoparticles is smaller than that of SiO₂/PS hybrid nanoparticles, meanwhile, the surface roughness of SiO₂/PS‐b‐PMPTS hybrid nanoparticles is yet slightly rougher than that of SiO₂/PS hybrid nanoparticles, which shows that the combination and competition of surface chemistry and roughness of a solid material can finally determine its wettability. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Synthesis and characterization of polyrhodanine/nickel ferrite nanocomposite with an effective and broad spectrum antibacterial activity

Nickel ferrite nanoparticles were successfully synthesized via a co-precipitation approach, and then polyrhodanine/nickel ferrite nanocomposite (PRh/NiFe₂O₄) as an antimicrobial agent was fabricated by a chemical polymerization method. The synthesized NiFe₂O₄ nanoparticles and PRh/NiFe₂O₄ nanocomposite were chemically, magnetically and morphologically characterized using FTIR, FESEM, DLS, VSM and XRD techniques. The FESEM analysis showed that the NiFe₂O₄ nanoparticles had a polygon structure with an average diameter of 50 nm. According to disc diffusion as well as MIC and MBC tests, the PRh/NiFe₂O₄ nanocomposite had better antibacterial effects on killing Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli in comparison with the NiFe₂O₄ nanoparticles.     

Poly(L‐lactic acid)/silicon dioxide nanocomposite prepared via the in situ melt polycondensation of L‐lactic acid in the presence of acidic silica sol: Isothermal crystallization and melting behaviors

In a previous article, we reported the preparation and characterization of a nanocomposite of poly(L ‐lactic acid) (PLLA) and silica via the in situ melt polymerization of L ‐lactic acid in the presence of acidic silica sol. In this study, the isothermal crystallization and melting behaviors of a PLLA/silicon dioxide (SiO₂) nanocomposite with 5 wt % well‐dispersed SiO₂ nanoparticles (PLLASN5) and pure PLLA were comparatively studied with differential scanning calorimetry and polarized optical microscopy. The SiO₂ nanoparticles acted as nucleation agents in the PLLA matrix and enhanced its nucleation rate and overall crystallization rate, especially at high crystallization temperatures. However, no deleterious effect on the crystal morphology or crystallinity was observed. The crystals that formed at a low temperature were imperfect; therefore, double melting peaks occurred during the second heating scan because of melt recrystallization. With the crystallization temperature increasing, the crystals became increasingly perfect; as a result, the low melting peak increased and shifted to a higher temperature. The existence of SiO₂ nanoparticles had no effect on the equilibrium temperature of the PLLA matrix. Pure PLLA and PLLASN5 have the same equilibrium temperature of 171.5°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of silica nanopowder on the properties of wood flour/polymer composite

Low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), polypropylene (PP), and polyvinyl chloride (PVC) (1:1:1:0.5) were solution blended by using a mixture of solvents consisting of xylene and tetrahydrofuran (THF) (70:30). SiO₂ nanoparticles were modified by cetyl trimethyl ammonium bromide (CTAB). Wood polymer composites (WPC) were prepared by using polymer mixture, polyethylene‐co‐glycidyl methacrylate (PE‐co‐GMA), wood flour, and modified SiO₂. X‐ray diffraction (XRD) studies showed that the intensity of the peaks of polymer mixture decreased due to incorporation of SiO₂. The dispersion of SiO₂ nanoparticles and morphological characteristics were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The interaction between SiO₂ nanoparticles, PE‐co‐GMA, polymer mixture, and wood was studied by Fourier transform infrared spectroscopy (FTIR). Tensile and flexural properties of the composites improved significantly due to the incorporation of SiO₂ nanoparticles. Thermal stability, hardness, flame retardancy, and water resistance capacity were also found to enhance. Maximum improvement in properties was observed by the inclusion of 3 phr modified SiO₂ in WPC. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Core/shell SiOx@PAM nanospheres from UV‐assisted surface‐initiated free radical polymerization

The core/shell SiO_x@polyacrylamide (SiO_x@PAM) nanospheres were successfully prepared by the in situ surface‐initiated free radical polymerization of acrylamide (AM) from the silica nanoparticles with self‐assembled monolayers (SAMs) of N‐methyl aniline (NMA) in presence of benzophonone via a precipitation polymerization method under the ultraviolet (UV) irradiation. The conversion of monomer (C%) and the percentage of encapsulating (PE%), calculated from the elemental analyses (EA) results, reached 20.9 and 51.0% after 150 min of UV‐irradiation, respectively. It is consistent with the analyses of TGA. Fourier transform infrared (FTIR) analyses also confirmed the formation of the core/shell SiO_x@PAM nanospheres. And it was investigated that the silica nanoparticles had been encapsulated with PAM from the X‐ray photoelectron spectrometer (XPS) analyses. The analysis results of transmission electron microscope (TEM) showed that the diameters of the SiO_x@PAM nanospheres were in the range of 50–200 nm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3433–3438, 2006