Sulfonic Acid-Functionalized Fe3O4 Reinforced Soluble Polyimide: Synthesis and Properties

In this study, a series of nanocomposite films based on an aromatic polyimide and sulfonic acid-functionalized magnetic nanoparticles was successfully prepared via an in situ technique. For this purpose, new soluble aromatic polyimide containing sulfone group as a polymeric matrix of the nanocomposites was synthesized. The surfaces of MNP were grafted with 3-mercaptopropyl trimethoxysilane. Then sulfonic acid-functionalized magnetic nanoparticle was obtained by oxidation of the thiol group. Effects of sulfonic acid-functionalized magnetic nanoparticles on thermal, tensile, and magnetic properties of the prepared nanocomposite films were studied. The magnetic nanoparticles containing the sulfonic acid groups could have strong intermolecular bond interactions between the hydroxyl groups of SO₃H and the sulfone and carbonyl groups of the polyimide matrix which caused the better dispersion of nanoparticle and exhibited superior mechanical properties, good magnetic properties, and high thermal stability.     

Synthesis and physicochemical investigation of imide-functionalized silica nanocomposites

The incorporation of inorganic nanoparticles into polymers have gained significant attention to improving functional properties. The ultimate nanocomposite behaviors are influenced by many parameters, such as microstructural distribution that are produced during the treatment process. Herein, a hybrid material integrating a modified network into a polyimide PI matrix was produced via the sol–gel method by the reaction of pyromellitic dianhydride, 4, 4-oxydianaline, and 1, 5-diaminonaphthalene to synthesize copolyimides nanocomposite. The modified polyimide and unmodified polyimide silica (SiO₂) nanoparticles were incorporated in the polyimide matrix to have polyimide silica nanocomposite. In modified silica nanoparticles, 3-aminopropyltriethosilane was introduced to have better compatibility among inorganic–organic hybrid with similar chemical contact due to their flexible alkyl group. The surface morphology or structure of silica and polyimide was affirmed by scanning electron microscopy, Fourier transforms infrared spectroscopy confirmed the synthesis of pure polyimide, unmodified polyimide, and modified polyimide silica via presence and absence of certain peaks. Thermogravimetric analysis (TGA) results showed high thermal stability of nanocomposites as silica content increases. In contrast to unmodified silica, the modified silica provides more thermal stability to the nanocomposites. Dynamic mechanical analysis was used to investigate the tensile stress of pure polyimide, unmodified, and modified silica nanocomposites. Thermal stability, storage modulus, and moisture absorption of these hybrid materials were improved with silica nanoparticles. The TG mass spectrum confirms the successful synthesis of modified silica networks. The substituted silica nanoparticles show higher mechanical toughness and storage in modified compared to unmodified silica nanocomposite, which exhibits stronger binding attraction between silica nanoparticles and polyimide matrix.     

Effect of particle size and grafting density on the mechanical properties of polymer nanocomposites

End-grafting polymer chains to nanoparticles in polymer nanocomposite is a widely used method to disperse inorganic particles in a polymeric matrix in order to improve the material properties. While many fundamental studies have investigated how various factors influence the dispersion or aggregation of the nanoparticles, the effect of grafting on the resulting material properties has received considerably less attention. In particular, the effect of nanoparticle curvature and grafting density on the mechanical properties in polymer nanocomposites remains elusive. In this study, we develop a coarse-grained model of a polymer glass containing grafted nanoparticles and examine the resulting effects on the mechanical properties. By carefully designing the parameters of our polymer nanocomposites model, we can maintain dispersion of the nanoparticles whether they are grafted with polymer chains or not, which allows us to isolate the effect of end-grafting on the resulting mechanical properties. We examine how the nanoparticle size and grafting density affect the elastic constants, strain hardening modulus, as well as the mobility of the polymer segments during deformation. We find that the elastic constants and yield properties are enhanced nearly uniformly for all of our nanocomposite systems, while the strain hardening modulus depends weakly on the grafting density and the nanoparticle size.     

Anisotropy investigation of cobalt ferrite nanoparticles embedded in polyvinyl alcohol matrix: A Monte Carlo study

The magnetic properties of the cobalt ferrite/polyvinyl alcohol nanocomposites have been studied experimentally and theoretically. For investigation the impact of polymeric matrix on magnetic properties of magnetic nanoparticles, four different processes have been considered for synthesizing the polymer based nanocomposites by co-precipitation method. The effective magnetic anisotropy obtained by Monte Carlo simulation and law of approach to the saturation magnetization showed a significant decrease relative to the bulk and bare cobalt ferrite nanoparticles. The polymeric matrix interacted with the surface of particles by different strength and made them approximately non-interacting. The as synthesized samples characterized by X-Ray diffractions (XRD) and Fourier transform infrared spectroscopy (FT-IR). Magnetic measurements were carried out at room temperature using a vibrating sample magnetometer (VSM).     

Effect of the nanoparticles on the morphology and mechanical performance of thermally blown 3D printed HIPS foams

Cellular polymer nanocomposites can combine high mechanical performance with low density. However, the manufacturing of porous nanocomposites into complex shapes can represent a challenge. Therefore, this article deals with the preparation, characterization, and 3D printing of porous nanocomposites. The filaments were extruded from the polymer nanocomposite filled by thermal chemical blowing agent, and then processed by 3D printing into the required shapes. In-situ and post-treatment foaming strategies were investigated and compared. The nanoparticles (NPs) significantly affected the processing, structure, thermal and mechanical properties of polymeric foams. The NPs, serving as a nucleating agent, allowed preparation of smaller pores and led to finer and more homogeneous foams. At the same time, they reinforced foam walls and thus improved mechanical properties. Moreover, NPs catalyzed decomposition of the blowing agent grains at lower temperature which brought about faster and more efficient foaming. This study showed the straightforward approach to prepare mechanically robust lightweight 3D printed materials.     

Studies on the Mechanical,Electrical Properties and Interaction of Petroleum Fuels with SBR/ Manganous Tungstate Nanocomposites

A novel nanocomposite based on styrene butadiene rubber (SBR) and manganous tungstate (MnWO₄) nanoparticles was prepared by a simple and inexpensive open two-roll mixing mill. The interaction of the nanoparticles with SBR matrix was studied by different characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and electrical properties. The effect of loading of MnWO₄ nanoparticles on the processing characteristics of mixed rubber compounds, mechanical properties and the transport properties of nanocomposites through petroleum fuels were also analysed. XRD of nanocomposite revealed that the addition of nanoparticles imparts a semi-crystalline or regular arrangement of chains in the composite. SEM analysis showed good dispersion of nanoparticles in the polymer matrix. Also it has been observed that the dispersion of nanoparticles decreases with increase in its loading. TGA analysis indicated better thermal stability of all nanocomposite and thermal stability increases with the loading of the nanoparticles. The AC conductivity and dielectric properties were greatly enhanced in the whole range of frequencies studied. The processing properties of rubber compounds like cure and scorch time decreases with increase in concentration of MnWO₄ nanoparticles and the maximum enhancement in torque was observed for 10 phr loading. The tensile strength, modulus, tear resistance, hardness and heat build-up of the composite increased whereas the resilience, compression set and elongation at break decreased with the loading of nanoparticles. Solvent penetration studies of nanocomposites were done in petroleum fuels at different temperatures.The solvent uptake was the minimum for composite with 10 phr of MnWO₄ and penetration of solvent increased with further addition of nanoparticles.     

Synthesis and properties of ZnS/ polyimide nanocomposite films

A series of ZnS/polyimide (PI) nanocomposite films with different ZnS contents have been successfully fabricated by incorporating ZnS nanoparticles with a diameter of 2–5 nm into polyamic acid, followed by a stepwise thermal imidization process. X‐ray photoelectron spectroscopy results confirm the successful introduction of ZnS particles into PI matrix. Transmission electron microscopy images show that the ZnS nanoparticles were uniformly dispersed in the polymer matrix without aggregation. The incorporation of ZnS nanoparticles can improve the mechanical properties and the glass transition temperature of nanocomposites, while the thermal degradation temperature of nanocomposites decreases with increasing ZnS content. Copyright © 2006 Society of Chemical Industry Society of Chemical Industry     

Combinatorial methods for polymer materials science: Phase behavior of nanocomposite blend films

Polymer materials are often mixed with inorganic materials in the bulk to enhance properties, including mechanical, electrical, thermal, and physical. Such property enhancements are induced not only by the physical presence of the filler but also significantly by the interaction of the polymer with the filler via altering the local properties of the polymer material. In this regard, recently layered silicate nanocomposites have been shown to be effective in modifying the polymer properties because of their high surface area of contact between the polymer and the high aspect ratio nanoparticle. Potential property enhancements should also occur in polymer nanocomposite thin films owing to nanoparticle orientation from film confinement effects. In this paper we investigate the effect of layered silicate nanoparticles on the phase behavior of a classic polymer blend using small angle neutron scattering and compare those results to phase diagrams obtained by high throughput combinatorial methods.     

Foams based on low density polyethylene/hectorite nanocomposites: Thermal stability and thermo‐mechanical properties

Novel polymer nanocomposite foams made by a two step compression molding method are analyzed in this article. Nanocomposites of low density polyethylene and an organo‐modified hectorite were first melt compounded and then foamed using a compression molding method. To study the influence of the presence and the amount of hectorite in both mechanical and thermal properties, samples with 3% and 7% content of hectorite were prepared. Polyethylene crystalline characteristics and thermal stability of the samples were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Mechanical properties of foams and solid nanocomposites were analyzed by using dynamical mechanical analysis (DMA). Thermal expansion of the samples was analyzed by thermomechanical analysis. The results indicate that the exfoliation of hectorite platelets was achieved after the foaming process, but not during the melt mixing step. Foams with hectorite nanoparticles exhibit improved thermal stability and mechanical properties when compared with neat polymeric foams. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis,characterization, and properties of new conducting polyaniline/copper sulfide nanocomposites

This article reports the facile synthesis of copper sulfide (CuS)/polyaniline (PANI) nanocomposites by in situ polymerization. The composites were characterized by scanning electron microscopy (SEM), UV–visible and Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). SEM analysis showed that the metal sulfide nanoparticles were uniformly dispersed in the polymer matrix. The characteristic peaks in FTIR and UV–vis spectra of PANI were found to be shifted to higher wave numbers in PANI/CuS composite, which is attributed to the interaction of CuS nanoparticles with PANI chain. XRD pattern revealed the structurally ordered arrangement of polymer composite and this regularity increases with increase in concentration of nanoparticles. Glass transition temperature of the nanocomposite increased with increase in the concentration of nanoparticles and it indicated the ordered arrangement of the polymer composite than PANI. TGA studies indicated excellent thermal stability of polymer nanocomposite. The electrical properties of nanocomposites were studied from direct current and alternating current resistivity measurement. Conductivity, dielectric constant, and dissipation factor of the nanocomposite were significantly increased with the increase in CuS content in the nanocomposite. The enhancement of these properties suggests that the proposed PANI/CuS nanocomposites can be used as multifunctional materials for nanoelectronic devices. POLYM. ENG. SCI., 54:438–445, 2014. © 2013 Society of Plastics Engineers     

Preparation and properties of exfoliated nanocomposites through intercalated a photoinitiator into LDH interlayer used for UV curing coatings

The exfoliated polymer/layered double hydroxide (LDH) nanocomposites based on MgAl were prepared through intercalating a photoinitiator into LDH interlayer, following by UV irradiation induced polymerization. The fragmental photoinitiator, 2-hydroxy-2-methyl-1-phenylpropane-1-one (1173) firstly reacted with isophorone diisocyanate (IPDI) to obtain the semiadduct, 1173-IPDI, and then reacted with the LDH modified by aminoundecanoic acid, obtaining LDH-1173 with an intercalated microstructure, which was characterized by FTIR, XRD, and TGA measurements. The obtained LDH-1173 was mixed with the multifunctional acrylate oligomer and monomer, and then exposed to a UV lamp to prepare a polymer/LDH nanocomposite. From the XRD, TEM and HR-TEM analysis, as well the photopolymerization kinetics investigation, it was found that the LDH-1173 effectively initiated the photopolymerization of acrylates, and formed exfoliated polymer/LDH nanocomposites. However, the mostly intercalated polymer/LDH nanocomposites were obtained for the systems with additional 1173 except for LDH-1173 addition. Compared with the pure polymer material, both the exfoliated and intercalated polymer/LDH nanocomposites exhibited the enhancements in mechanical and thermal properties, as well as hardness.     

New Magnetic Polymer Nanocomposites on the Basis of Isotactic Polypropylene and Magnetite Nanoparticles for Adsorption of Ultrahigh Frequency Electromagnetic Waves

In this study, we report about the preparation of magnetic polymer nanocomposites on the basis of isotactic polypropylene and magnetite Fe₃O₄ nanoparticles. The structure and composition of polymer nanocomposite materials have been studied by scanning electron microscopy, atomic force microscopy, and X-ray dispersive analysis. The magnetic properties of polymer nanocomposites based on PP+Fe₃O₄have been investigated. It is found that not significant adhesion and agglomeration of nanoparticles occur, by increasing the nanoparticle content in polymer matrix up to 40%, and therefore they act as single-domain nanoparticles. The samples of nanocomposites based on PP+Fe₃O₄, with up to 40% content of Fe₃O₄, exhibit superparamagnetic properties. It was also found out that the magnetic polymer nanocomposite material based on PP+Fe₃O₄ is able to absorb ultrahigh frequency electromagnetic waves in the frequencies range from 0.1 to 30?GHz. The increase in Fe₃O₄ concentration from 5 to 40% at the 400?µm thicknesses of the films leads to an increase in absorption of electromagnetic waves of high frequency from 15 to 22.7%.     

Poly dimethylsiloxane/carbon nanofiber nanocomposites: fabrication and characterization of electrical and thermal properties

This article presents the fabrication and characterization of poly dimethylsiloxane/carbon nanofiber (CNF)-based nanocomposites. Although silica and carbon nanoparticles have been traditionally used to reinforce mechanical properties in PDMS matrix nanocomposites, this article focuses on understanding their impacts on electrical and thermal properties. By adjusting both the silica and CNF concentrations, 12 different nanocomposite formulations were studied, and the thermal and electrical properties of these materials were experimentally characterized. The developed nanocomposites were prepared using a solvent-assisted method providing uniform dispersion of the CNFs in the polymer matrix. Scanning electron microscopy was employed to determine the dispersion of the CNFs at different length scales. The thermal properties, such as thermal stability and thermal diffusivity, of the developed nanocomposites were studied using thermogravimetirc and laser flash techniques. Furthermore, the electrical volume conductivity of each type of nanocomposite was tested using the four-probe method to eliminate the effects of contact electrical resistance during measurement. Experimental results showed that both CNFs and silica were able to impact on the overall properties of the synthesized PDMS/CNF nanocomposites. The developed nanocomposites have the potential to be applied to the development of new load sensors in the future.     

Effects of facile amine‐functionalization on the physical properties of epoxy/graphene nanoplatelets nanocomposites

Graphene nanoplatelets (GNPs) have excellent thermal, electrical, and mechanical properties. The incorporation of GNPs into a polymer can remarkably enhance the thermal and mechanical properties of the polymer especially when GNPs are well dispersed in the polymer matrix with strong interfacial bonding. Therefore, in this study, GNPs were amine‐functionalized by covalently bonding 4,4′‐methylene dianiline onto their surfaces via a facile synthetic route. The amine‐functionalization was confirmed by FTIR spectroscopy and TGA. Epoxy/GNPs nanocomposites were prepared and their curing behavior, thermomechanical properties and impact strength were investigated. The amine‐functionalization increased curing rate, storage modulus, thermal dimensional stability, and impact strength of the nanocomposites. The SEM images for the fracture surface of the nanocomposite with amine‐functionalized GNPs showed a smooth and ductile failure‐like surface, resulted from the improved interfacial bonding between GNPs and the epoxy matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42269.     

Microstructure and thermal properties of ethylene‐(vinyl acetate) copolymer/rectorite nanocomposites

Ethylene‐(vinyl acetate) copolymer (EVA)/rectorite nanocomposites were prepared by direct melt extrusion of EVA and organo‐rectorite. The microstructures and thermal properties of EVA nanocomposites were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), solid‐state nuclear magnetic spectroscopy, positron annihilation spectroscopy, thermal gravimetric analysis (TGA) and dynamic mechanical analysis techniques. XRD pattern and SEM images show that the intercalated structure is formed and rectorite is finely dispersed in EVA matrix. When organoclay content of the hybrid increases to 7.5 wt%, or pristine rectorite was used instead of organoclay, the crystallization behavior of EVA nanocomposite changes greatly and the ratio of the monoclinic to orthorhombic crystal increases significantly. The relative fractional free volume of the nanocomposite decreases with the increasing organo‐rectorite content, and the values of damping factor (tan δ) for all nanocomposites are lower than that of pure EVA. These facts illuminate that intercalated structure restricts the segment motion and mobilization of polymer chain. TGA results of EVA nanocomposites in air indicate that deacylation of EVA is accelerated because of the catalytic effect and the thermal degradation of the main chain is delayed owing to the barrier effect of silicate layers. Copyright © 2005 Society of Chemical Industry     

Synthesis,characterisation and flame,thermal and electrical properties of poly (<Emphasis Type="Italic">n</Emphasis>-butyl methacrylate)/titanium dioxide nanocomposites

Nanocomposites based on poly (n-butyl methacrylate) (PBMA) with various concentrations of titanium dioxide (TiO₂) nanoparticles were synthesised by in situ free radical polymerisation method. The formation of nanocomposite was characterised by FTIR, UV, XRD, DSC, TGA, impedance analyser and flame retardancy measurements. FTIR and UV spectrum ascertained the intermolecular interaction between nanoparticles and the polymer chain. The XRD studies indicated that the amorphous region of PBMA decreased with the increase in content of metal oxide nanoparticles. The SEM revealed the uniform dispersion of nanoparticles in the polymer composite. The DSC and TGA studies showed that the glass transition temperature and thermal stability of the nanocomposites were increased with the increase in the concentration of nanoparticles. The conductivity and dielectric properties of nanocomposites were higher than pure PBMA and the maximum electrical property was observed for the sample with 7 wt% TiO₂. As the concentration of nanoparticles increased above 7 wt%, the electrical property of nanocomposite was decreased owing to the agglomeration of nanoparticles in the polymer. Nanoparticles could impart better flame retardancy to PBMA/TiO₂ composite and the flame resistance of the materials improved with the addition of nanoparticles in the polymer matrix.     

Role of copper alumina nanoparticles on the performance of polyvinylchloride nanocomposites

Poly(vinyl chloride) (PVC) nanocomposites with different contents of copper alumina (Cu-Al₂O₃) nanoparticles were prepared by the solution casting method. The effects of the nanoparticles on structural, thermal, electrical, contact angle and mechanical properties were thoroughly examined. The presence of Cu-Al₂O₃ in the macromolecular chain was confirmed through Fourier transform infrared (FTIR) spectroscopy. The X-ray diffraction (XRD) analysis of PVC nanocomposites showed the systematic arrangement of Cu-Al₂O₃ nanoparticles within the polymer, which indicated the higher crystallinity of the nanocomposites. The surface morphology of PVC was changed into hemispherical shaped particles by the inclusion of nanofiller was analyzed from SEM images. The glass transition temperature of the nanocomposites obtained from differential scanning calorimetry (DSC) was found to be increased with an increase in loading of nanoparticles in the polymer. The AC conductivity and dielectric studies revealed that the inclusion of nanofiller increases the electrical properties of the material and the composite with 7 wt.% sample showed the maximum conductivity and dielectric constant. The mechanical properties such as modulus, tensile strength, hardness, and impact properties of the PVC nanocomposites were significantly enhanced by the reinforcement of nanoparticles into the PVC matrix. The reinforcing mechanism behind the increase in tensile strength with the addition of nanoparticles was correlated with different theoretical models. The highest mechanical and electrical properties were observed for 7 wt.% Cu-Al₂O₃ loaded nanocomposite. Contact angle measurements of PVC with various loadings of Cu-Al₂O₃ nanofillers demonstrated that the nanoparticle attachment increased the hydrophobicity of the polymer matrix.     

HES-HEMA nanocomposite polymer hydrogels: swelling behavior and characterization

Organophilic sodium montmorillonite (Na-MMT) and Laponite-RD clays were incorporated into photopolymerizable hydroxyethyl starch (HES) modified with 2-hydroxyethyl methacrylate (HEMA). Swelling, mechanical properties and thermal stability of obtained crosslinked nanocomposite polymers were evaluated. A camphorquinone-amine system was used as photoinitiating system in visible light. The interaction between nano-sized filler particles and polymer hydrogel was evaluated by FT-IR spectroscopy and the platelet distribution was investigated by SEM. An increased thermal stability of nanocomposite polymers upon addition of clay was observed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicating interaction between the clay platelets and the polymer chains. The crosslinking density for HES-HEMA/MMT nanocomposite hydrogels as investigated by swelling measurements increases with increasing the organo-clay content. The mechanical properties of virgin hydrogels were improved by the introduction of organo-clay as evidenced by oscillation rheology measurements. Whereas, the increase in crosslink density and storage modulus with clay content for laponite was found to be increasing for all concentrations investigated, for MMT there is an optimum content of ca. 1.5 wt%.     

Biological Degradation and Biostability of Nanocomposites Based on Polysulfone with Different Concentrations of Reduced Graphene Oxide

Increasing incorporation of rGO in the polysulfone polymer generates materials with improved chemical and mechanical stability and less prone to biodegradation at the end of the nanocomposite life cycle. The results of attenuated total reflection infrared (ATR‐IR) and mechanical strength, after exposure to wastewater influent, show that the increasing concentrations of rGO into the polymer matrix reduce changes in the nanocomposite properties. The increasing incorporation of rGO also increases growth inhibition of the wastewater microbial population on the surface of nanocomposites. Highest biofilm inhibition and material stability are observed with nanocomposites containing 3 wt% rGO. These results suggest that reduction in the material biodegradation is linked to the inhibition of biofilm growth on the nanocomposite surface due to the antimicrobial properties of rGO. This study demonstrates, for the first time, that the amount of rGO incorporated in the nanocomposite impact the biodegradability and end of life of polysulfone nanocomposites.     

Soft nanocomposites: nanoparticles to tune gel properties

The demand for new, soft materials with bespoke physical and biological characteristics and functionality has fuelled the research into nanocomposite hydrogels. ‘Soft’ nanocomposites – nanoparticles within a hydrated, polymeric gel matrix – offer a simple, yet versatile, platform for the design of materials with specific – and tunable – properties. Indeed, the ‘soft’ properties of the matrix can be combined with the inherent functionality of the nanoparticles (drug loading, antimicrobial, light refraction etc.) or give rise to altogether new characteristics (toughness, optical properties, self‐healing etc.) evolved from the synergistic interaction of the polymer chains with the particles. In this review, we report the evolution and achievements of nanocomposite gels, with a focus on mechanisms and structure. The review is therefore structured around the properties resulting from the gel/nanoparticle association, rather than a classification based on applications or specific types of polymer or nanoparticles. How can nanoparticles tune mechanical, optical, biological properties or impart stimuli‐responsiveness to a polymer gel matrix ? and how is this behaviour linked to the underlying structure? © 2015 Society of Chemical Industry