In situ fabrication of polyaniline‐silver nanocomposites using soft template of sodium alginate

Polyaniline (PANI)‐Ag nanocomposites were synthesized by in situ chemical polymerization approach using ammonium persulfate and silver nitrate as oxidant. Characterizations of nanocomposites were done by ultraviolet–visible ( UV–vis), Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM). UV–vis, XRD and FTIR analysis established the formation of PANI/Ag nanocomposites and face‐centered‐cubic phase of silver. PANInanofibers were of average diameter ～ 30 nm and several micrometers in length. Morphological analysis showed that the spherical‐shaped silver nanoparticles decorate the surface of PANI nanofibers. Silver nanoparticles of average diameter ～ 5–10 nm were observed on the TEM images for the PANI‐Ag nanocomposites. Such type of PANI‐Ag nanocomposites can be used as bistable switches as well as memory devices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Development and Characterization of Curcumin Loaded Silver Nanoparticle Hydrogels for Antibacterial and Drug Delivery Applications

The present work involves the development of curcumin loaded silver hydrogel nanocomposites based on acrylamide and 2-acrylamido-2-methyl propanesulfonic acid, as a template by redox co-polymerization in the presence of hydrophilic crosslinker N,N ¹-methylenebisacrylamide. Silver nitrate was taken as the metal precursor and sodium borohydride as a reducing agent. The formation of silver nanoparticles was monitored using UV–Vis absorption spectroscopy. The developed hydrogel silver nanocomposites (HSNC) were characterized by FTIR, UV–Vis, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The curcumin loading and release characteristics were performed for different hydrogel systems. The developed HSNCs were evaluated for preliminary antibacterial applications.     

Magnetic and electric responsive hydrogel–magnetic nanocomposites for drug‐delivery application

Magnetic and electrically responsive hydrogel networks were developed for drug‐delivery applications. The hydrogel matrices were synthesized by the polymerization of acrylamide monomer in the presence of carboxymethylcellulose (CMC) or methylcellulose (MC) with N,N‐methylenebisacrylamide, a crosslinker with the redox initiating system ammonium persulfate/tetramethylethylenediamine. The magnetic nanoparticles were generated throughout these hydrogel matrices by an in situ method by the incorporation of iron ions and their subsequent reduction with ammonia. A series of hydrogel–magnetic nanocomposites (HGMNCs) were developed with various CMC and MC compositions. The synthesized HGMNCs were characterized with spectral (Fourier transform infrared and ultraviolet–visible spectroscopy), X‐ray diffraction, thermal, and microscopy methods. These HGMNCs contained iron oxide (Fe₃O₄) nanoparticles with an average particle size of about 22 nm, as observed by transmission electron microscopy. The dielectrical properties of the pure hydrogel (HG); the hydrogel loaded with iron ions, or the hydrogel iron‐ion composite (HGIC); and the HGMNCs were measured. These results suggest that HGMNCs exhibited higher dielectric constants compared to HG and HGICs. The curcumin loading and release characteristics were also measured for HG, HGIC, and HGMNC systems. These data revealed that there was a sustained release of curcumin from HGMNCs because of the presence of magnetic nanoparticles in the hydrogel networks. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of modified sodium lignosulfonate hydrogel–silver nanocomposites

In this article, modified sodium lignosulfonate (MSLS) hydrogel particles were prepared using sodium lignosulfonate as starting material. The hydrogel particles exhibit a reversible property transformed between the two states of macrohydrogel and microhydrogel by ultrasonic dispersion and vacuum drying. Using this property, highly stable and uniformly dispersed silver nanoparticles (AgNPs) have been prepared via in situ reduction of silver ions (silver nitrate) in the microhydrogel aqueous dispersion with sodium borhydride. The hybrid microhydrogel with AgNPs was transformed into MSLS hydrogel–silver nanocomposites by drying under vacuum at 40°C. X‐ray diffraction, ultraviolet–visible (UV–vis) spectrophotometry, Fourier transform infrared spectra, atomic absorption spectroscopy, transmission electron microscopy, and scanning electron microscopy were used to characterize the composite system. The results show that the size of spherical silver nanoparticles incorporated in the hydrogel framework is about 10 nm. POLYM. COMPOS., 34:860–866, 2013. © 2013 Society of Plastics Engineers     

Hydrogel–silver nanoparticle composites: A new generation of antimicrobials

Design of consistant and eco‐friendly methods for the synthesis of silver nanoparticles (AgNPs) is a significant forward direction in the field of application of antibacterial bionanotechnology. One among the available options is hydrogel templates, which are highly useful to achieve this goal. This investigation involves the development of poly(acrylamide)/poly(vinyl alcohol) hydrogel–silver nanocomposites (HSNCs) to achieve AgNPs of ～2–3 nm size in gel networks. The nanocomposite synthesis process is quite convenient, direct, and very fast, and the obtained hydrogel AgNP composites can be used for antibacterial and wound dressing applications. All the nanocomposite aqueous solutions have shown absorption peaks at 420 nm in UV–visible absorption spectrum corresponding to the Plasmon absorbance of AgNPs. X‐ray diffraction spectrum of the HSNC exhibited 2θ values matching with silver nanocrystals. Transmission electron microscopy images of nanocomposites represent discrete AgNPs throughout the gel networks in the range of 2–3 nm. The developed nanocomposites were evaluated for antibacterial application on E. coli. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Breathing‐in/breathing‐out approach to preparing nanosilver‐loaded hydrogels: Highly efficient antibacterial nanocomposites

The key objective of developing novel materials for hygienic living conditions is to lower the risk of transmitting diseases and biofouling. To this end, a number of silver–hydrogel nanocomposite systems are under development. In this study, we attempted a unique strategy to prepare silver‐nanoparticle‐loaded poly(acrylamide‐co‐N‐vinyl‐2‐pyrolidone) hydrogel composites. To load nanosilver particles into such a nonionic hydrogel, a novel breathing‐in/breathing‐out (BI–BO) approach was employed. As the number of BI–BO cycles increased, the amount of the silver nanoparticles loaded into these hydrogels also increased. This behavior was obvious and was confirmed by ultraviolet–visible spectroscopy and thermal analysis. Furthermore, the hydrogel–silver‐nanoparticle composites were confirmed with Fourier transform infrared spectroscopy and transmission electron microscopy studies. Antibacterial studies of these hydrogel–silver nanocomposites showed excellent results against Escherichia coli. The antibacterial activity increased with the number of BI–BO cycles, and samples that underwent three BI–BO cycles showed optimal bactericidal activity. The degree of crosslinking and the silver content had a great influence on the antibacterial efficacy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Studies on the synthesis of electrospun PAN‐Ag composite nanofibers for antibacterial application

We have successfully synthesized polyacrylonitrile (PAN) nanofibers impregnated with Ag nanoparticles by electrospinning method at room temperature. Briefly, the PAN‐Ag composite nanofibers were prepared by electrospinning PAN (10% w/v) in dimethyl formamide (DMF) solvent containing silver nitrate (AgNO₃) in the amounts of 8% by weight of PAN. The silver ions were reduced into silver particles in three different methods i.e., by refluxing the solution before electrospinning, treating with sodium borohydride (NaBH₄), as reducing agent, and heating the prepared composite nanofibers at 160°C. The prepared PAN nanofibers functionalized with Ag nanoparticles were characterized by field emission scanning electron microscopy (FESEM), SEM elemental detection X‐ray analysis (SEM‐EDAX), transmission electron microscopy (TEM), and ultraviolet‐visible spectroscopy (UV‐VIS) analytical techniques. UV‐VIS spectra analysis showed distinct absorption band at 410 nm, suggesting the formation of Ag nanoparticles. TEM micrographs confirmed homogeneous dispersion of Ag nanoparticles on the surface of PAN nanofibers, and particle diameter was found to be 5–15 nm. It was found that all the three electrospun PAN‐Ag composite nanofibers showed strong antibacterial activity toward both gram positive and gram negative bacteria. However, the antibacterial activity of PAN‐Ag composite nanofibers membrane prepared by refluxed method was most prominent against S. aureus bacteria. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Valproate‐Loaded hydrogel nanoparticles: Preparation and characterization

Developing a simple and efficient approach to formulate biodegradable nanoparticles for intravenous delivery of sodium valproate (a hydrophilic small molecule drug chronically used in epileptic patients), is the principal objective of the current study. To fabricate particles via ionotropic gelation approach, a polycation polymer (chitosan) along with a polyanion (tripolyphosphate) was utilized in the presence of sodium valproate, and the Taguchi experimental design method was drawn upon so as to determine the optimum conditions of nanoparticle generation. In the following step, the researchers investigated sodium valproate‐loaded nanoparticles to explore various features of the nanoparticles including drug loading parameters, particle size distribution, zeta‐potential, morphology, stability, yield, and in vitro drug release profile. Nanoparticles with sizes of 63 ± 1 nm (number‐based) and 79 ± 3.21 (volume‐based) were obtained with slightly negative zeta–potential, which was more positive in drug‐loaded nanoparticles than the unloaded ones. The TEM imaging of the hydrogel nanoparticles manifested spherical shapes and corroborated the size achieved via particle size analyzer. The loading efficiency, loading amount, and loading ratio were determined to be 21.81 ± 3.90%, 10.31 ± 1.82 (mg sodium valproate/g nanoparticle) and 23.70 ± 4.54%, respectively, in optimum conditions. Moreover, there was observed a gradual drug release for nearly a week consisting, in average, about 94.64 ± 2.71% of the nanoparticles' drug content. In a nutshell, the present study introduces a practical, simple, and effective ionotropic gelation approach to generate sodium valproate‐loaded nanoparticles, leaving open a window of promising prospects in the field of intravenous long‐term delivery of this chronically used drug. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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.     

Synthesis and characterization of novel silver/L‐phenylalanine‐based optically active polyacrylate nanocomposite

Novel bioactive and optically active poly(N‐acryloyl‐L ‐phenylalanine) (PAPA) was synthesized by atom transfer radical polymerization. PAPA‐silver (Ag) nanocomposites have been successfully prepared via in situ reducing Ag⁺ ions anchored in the polymer chain using hydrazine hydrate as reducing agent in an aqueous medium. By controlling of the amount of Ag⁺ ions introduced, we have produced an organic/inorganic nanocomposite containing Ag nanoparticles with well controlled size. Nanocomposites were characterized by X‐ray diffraction (XRD), UV–Vis spectrophotometry, transmission electron microscopy, and Fourier transform infrared. XRD pattern showed presence of Ag nanoparticles. The PAPA/Ag nanocomposites with 1 : 10 silver nitrate (AgNO₃) : PAPA ratio revealed the presence of well‐dispersed Ag nanoparticles in the polymer matrix. All of these Ag nanoparticles formed are spherical and more than 80% of them are in the range of 15–25 nm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Antibacterial activity and cytotoxicity of hydrogel–nanosilver composites based on copolymers from 2‐acrylamido‐2‐methylpropanesulfonate sodium

In this research, we contributed to the search for potential hydrogel–silver dressings by generating hydrogel–silver nanoparticles (AgNPs) composites prepared by the dipping of the crosslinked hydrogel poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium) (1:1) and poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium) (1:1) into an aqueous suspension of citrate‐stabilized AgNPs. The composites obtained were evaluated by an antibacterial activity assay on Staphylococcus aureus and Escherichia coli and subjected to an in vitro cytotoxicity assay for human fibroblasts. The composite formed from the hydrogel poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium) with 3 mol % N,N‐methylene bisacrylamide showed the highest antibacterial activity and the least cytotoxicity among the composites tested; this makes it an excellent alternative as a potential dressing for the treatment of deep and exudative wounds. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39644.     

Facile synthesis and antibacterial evaluation of poly(acrylamide‐co‐(β‐cyclodextrin))/silver nanocomposite

Hydrogel/silver nanocomposites have shown immense potential in many biological applications. In this article, a facile method to synthesize poly(acrylamide‐co‐(β‐cyclodextrin))/silver nanocomposites is reported. The silver nanoparticles were in situ synthesized accompanying with the formation of poly(acrylamide‐co‐(β‐cyclodextrin)) hydrogel by gamma irradiation without additional reducing and stabilizing agents. In addition, the nanocomposites were prepared under ambient conditions. The formation of silver nanoparticles was confirmed by ultraviolet used to characterize the structure and composition of the synthetic nanocomposites. Transmission electron microscope verified the formation and homogeneous distribution of silver nanoparticles in the hydrogel matrix. The hybrid hydrogel exhibited excellent water‐swelling properties, which could be controlled by varying the mass ratio of acrylamide (AM) to β‐cyclodextrin (β‐CD) in the hydrogel. Furthermore, the poly(acrylamide‐co‐(β‐cyclodextrin))/silver nanocomposites were found to be effective in inhibiting the growth of both Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus. POLYM. COMPOS., 37:1480–1487, 2016. © 2014 Society of Plastics Engineers     

Nanocomposites of silver nanoparticle and dinonylnaphthalene disulfonic acid‐doped thermoreversible polyaniline gel

Silver/polyaniline‐dinonylnaphthalene disulfonic acid (PANI‐DNNDSA) gel nanocomposites are prepared from the reduction of silver salt by polyaniline in formic acid medium. Scanning electron micrographs (SEM) indicate the presence of three‐dimensional fibrillar network structure and the silver nanoparticles remain dispersed within the PANI‐DNNDSA fibrillar network. Differential scanning calorimetric (DSC) study shows reversible first‐order phase transition characterizing the composite to behave as a thermoreversible gel. Transmission electron micrographs (TEM) show a decrease of nanoparticle size with increasing AgNO₃ concentration. Wide angle X‐ray scattering (WAXS) patterns show lamellar structure in the gel as well as in the gel metal nanocomposites (GMNCs) and the two melting peaks in the DSC patterns correspond to the melting of monolayer and bilayer crystals produced from the interdigitation of DNNDSA tails anchored from PANI chains within the PANI lamella. The above melting points are greater in the GMNCs than that of pure gel indicating the formation of complex melting thermogram with crystallites produced from the anchored surfactants tails at the surface of Ag nanoparticles. The GMNCs show a higher thermal stability than that of pure PANI‐DNNDSA gel. PANI‐DNNDSA gel has an emission peak at 354 nm but fluorescence quenching occurs in the GMNCs and the emission peak becomes red shifted. Also in the UV–vis spectra the π band‐polaron band transition peak shows a red shift and the DC conductivity increases with increasing Ag nanoparticle concentration in the GMNCs. The current (I)–voltage (V) characteristic curves indicate Ohmic nature of conductivity of the gel and the current at the same voltage increases appreciably with increasing Ag nanoparticle concentration. These GMNCs are easily processible due to its thermoreversible nature. So, an easily processible, thermally stable and highly conducting DNNDSA‐doped PANI‐Ag gel nanocomposite with interesting photoluminescent property has been successfully developed suitable for optoelectronic applications. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Novel electrically conductive and ferromagnetic composites of poly(aniline‐co‐aminonaphthalenesulfonic acid) with iron oxide nanoparticles: Synthesis and characterization

Nanocomposites of iron oxide (Fe₃O₄) with a sulfonated polyaniline, poly(aniline‐co‐aminonaphthalenesulfonic acid) [SPAN(ANSA)], were synthesized through chemical oxidative copolymerization of aniline and 5‐amino‐2‐naphthalenesulfonic acid/1‐amino‐5‐naphthalenesulfonic acid in the presence of Fe₃O₄ nanoparticles. The nanocomposites [Fe₃O₄/SPAN(ANSA)‐NCs] were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, elemental analysis, UV–visible spectroscopy, thermogravimetric analysis (TGA), superconductor quantum interference device (SQUID), and electrical conductivity measurements. The TEM images reveal that nanocrystalline Fe₃O₄ particles were homogeneously incorporated within the polymer matrix with the sizes in the range of 10–15 nm. XRD pattern reveals that pure Fe₃O₄ particles are having spinel structure, and nanocomposites are more crystalline in comparison to pristine polymers. Differential thermogravimetric (DTG) curves obtained through TGA informs that polymer chains in the composites have better thermal stability than that of the pristine copolymers. FTIR spectra provide information on the structure of the composites. The conductivity of the nanocomposites (～ 0.5 S cm^?1) is higher than that of pristine PANI (～ 10^?3 S cm^?1). The charge transport behavior of the composites is explained through temperature difference of conductivity. The temperature dependence of conductivity fits with the quasi‐1D variable range hopping (quasi‐1D VRH) model. SQUID analysis reveals that the composites show ferromagnetic behavior at room temperature. The maximum saturation magnetization of the composite is 9.7 emu g^?1. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of neodymium‐doped titanium dioxide nanoparticles on the structural,mechanical, and electrical properties of poly(butyl methacrylate) nanocomposites

Nanocomposites based on neodymium‐doped titanium dioxide (Nd‐TiO₂)/poly(n‐butyl methacrylate) (PBMA) have been prepared by an in situ polymerization of butyl methacrylate monomer with varying concentrations of Nd‐TiO₂ nanoparticles. The resulting nanocomposites have been analyzed by ultraviolet (UV)–Visible spectroscopy, Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis, and impedance analyzer (TGA). The results of UV and FTIR spectroscopy have indicated the interaction of nanoparticles with the PBMA matrix. Spherically shaped nanoparticles with an average size of 10–25 nm have been revealed in the TEM and their homogeneous dispersion, and interaction of polymer matrix has been confirmed by SEM and XRD studies. The thermal stability and glass transition temperature of the composites were significantly enhanced by the addition of nanoparticles. The AC conductivity and dielectric properties of nanocomposites have been found to be higher than pure PBMA, and the maximum electrical properties have been observed for 7 wt% composite. The reinforcing nature of the nanoparticles in PBMA has been reflected in the improvement in tensile strength measurements. The result indicated that the tensile strength of nanocomposites have greatly enhanced by the addition of Nd‐TiO₂ nanoparticles whereas the elongation at break decreases with the loading of nanofillers. To understand the mechanism of reinforcement, tensile strength values have been correlated with various theoretical modeling. The research has been found to be promising in the development of novel materials with enhanced tensile strength, dielectric constant, and thermal properties, which may find potential applications in energy storage and nanoelectronic devices. J. VINYL ADDIT. TECHNOL., 25:9–18, 2019. © 2018 Society of Plastics Engineers     

Microemulsion route to fabrication of silver and platinum‐polymer nanocomposites

Polymethylmethacrylate (PMMA)‐platinum and PMMA‐silver nanocomposites have been produced using polymerization of W/O microemulsions. MMA monomer was used as the oil or continues phase of the microemulsion system and polymerized following formation of Pt and Ag nanoparticles in the fluid medium. The UV‐vis absorption spectra have been used to trace the growth process of the nanoparticles in the microemulsion system. Scanning electron microscopy and transmission electron microscopy (TEM) have been used to determine the morphology and particle size of the Pt and Ag particles in the synthesized nanocomposites. Image analyses of TEM micrographs confirm that the Pt and Ag particles in the synthesized nanocomposites have a narrow size distribution. Meanwhile, Fourier‐transform infrared spectroscopy was used to verify polymer‐nanoparticles interaction in nanocomposite bulk. POLYM. COMPOS., 35:2023–2028, 2014. © 2014 Society of Plastics Engineers     

Enhanced surface morphology and transport property of poly(N‐vinylcarbazole)/gold nanocomposite Langmuir–Schaefer films

A composite of poly(N‐vinylcarbazole) (PVK) containing gold nanoparticles (GNPs) was synthesized via simple solid‐state in situ bulk polymerization of N‐vinylcarbazole in the presence of GNPs at a high temperature. Both PVK and PVK–GNP composites were characterized by Fourier transform infrared (FTIR) and UV–vis spectroscopy. The surface morphology of the composites was studied by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy, and transmission electron microscopy (TEM). Thermal stability was identified via thermogravimetric analysis. The composites were fabricated into films using the Langmuir–Schaefer process. The enhancement in the characteristics of room temperature I–V, pressure–area isotherms, and photoelectrochemical behaviors was observed in the composite films. Results suggest that a charge transfer process occurs across the hybrid at the interface of the PVK–GNP composites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Preparation and characterization of poly(ϵ‐caprolactone‐co‐p‐dioxanone)–poly(ethylene glycol)–poly(ϵ‐caprolactone‐co‐p‐dioxanone)/bioactive inorganic particle nanocomposites

With an aim to develop injectable hydrogel with improved solution stability and enhanced bone repair function, thermogelling poly(ε‐caprolactone‐co‐p‐dioxanone)‐poly(ethylene glycol)‐poly(ε‐caprolactone–co‐p‐dioxanone) (PECP)/bioactive inorganic particle nanocomposites were successfully prepared by blending the triblock copolymer (PECP) with nano‐hydroxyapatite (n‐HA) or nano‐calcium carbonate (n‐CaCO₃). The hydrogel nanocomposites underwent clear sol–gel transitions with increasing temperature from 0 to 50°C. The obtained hydrogel nanocomposites were investigated by ¹H NMR, FT‐IR, TEM, and DSC. It was found that the incorporation of inorganic nanoparticles into PECP matrix would lead to the critical gelation temperature (CGT) shifting to lower values compared with the pure PECP hydrogel. The CGT of the hydrogel nanocomposites could be effectively controlled by adjusting PECP concentration or the content of inorganic nanoparticles. The SEM results showed that the interconnected porous structures of hydrogel nanocomposites were potentially useful as injectable scaffolds. In addition, due to the relatively low crystallinity of PECP triblock copolymer, the aqueous solutions of the nanocomposites could be stored at low temperature (5°C) without crystallization for several days, which would facilitate the practical applications. The PECP/bioactive inorganic particle hydrogel nanocomposites are expected to be promising injectable tissue engineering materials for bone repair applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mechanical and thermal properties of bio‐based CaCO3/soybean‐based hybrid unsaturated polyester nanocomposites

Bio‐based calcium carbonate nanoparticles (CaCO₃) were synthesized via size reduction of eggshell powder using mechanical attrition followed by high intensity ultrasonic irradiation. The transmission electron microscopic (TEM) and BET surface area measurements show that these particles are less than 10 nm in size and a surface area of ～44 m²/g. Bio‐based nanocomposites were fabricated by infusion of different weight fractions of as‐prepared CaCO₃ nanoparticles into Polylite® 31325‐00 resin system using a non‐contact Thinky® mixing method. As‐prepared bio‐nanocomposites were characterized for their thermal and mechanical properties. TEM studies showed that the particles were well dispersed over the entire volume of the matrix. Thermal analyses indicated that the bio‐nanocomposites are thermally more stable than the corresponding neat systems. Nanocomposite with 2% by weight loading of bio‐CaCO₃ nanoparticles exhibited an 18°C increase in the glass transition temperature over the neat Polylite 31325 system. Mechanical tests have been carried out for both bio‐nanocomposites and neat resin systems. The compression test results of the 2% Bio‐CaCO₃/Polylite 31325 nanocomposite showed an improvement of 14% and 27% in compressive strength and modulus respectively compared with the neat system. Details of the fabrication procedure and thermal and mechanical characterizations are presented in this article. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1442–1452, 2013     

Characterization of stabilized porous magnetite core–shell nanogel composites based on crosslinked acrylamide/sodium acrylate copolymers

Stabilized and dispersed superparamagnetic porous nanogels based on sodium acrylate (AA‐Na) and acrylamide (AM) in a surfactant‐free aqueous system were synthesized via solution polymerization at room temperature. The formation of magnetite nanoparticles was confirmed and their properties characterized using Fourier transform infrared spectroscopy. Extensive characterization of the magnetic polymer particles using transmission electron microscopy (TEM), dynamic light scattering and zeta potential measurements revealed that Fe₃O₄ nanoparticles were incorporated into the shells of poly(AM/AA‐Na). The average particle size was 5–8 nm as determined from TEM. AM/AA‐Na nanoparticles with a diameter of about 11 nm were effectively assembled onto the negatively charged surface of the as‐synthesized Fe₃O₄ nanoparticles via electrostatic interaction. Crosslinked magnetite nanocomposites were prepared by in situ development of surface‐modified magnetite nanoparticles in an AM/AA‐Na hydrogel. Scanning electron microscopy was used to study the surface morphology of the prepared composites. The morphology, phase composition and crystallinity of the prepared nanocomposites were characterized. Atomic force microscopy and argon adsorption–desorption measurements of Fe₃O₄.AM/AA indicated that the architecture of the polymer network can be a hollow porous sphere or a solid phase, depending on the AA‐Na content. © 2013 Society of Chemical Industry