Rheological and thermal properties of epoxy nanocomposites reinforced with alkylated multi‐walled carbon nanotubes

The effects of functionalized multi‐walled carbon nanotubes (MWCNTs) on thermal and chemorheological behaviors of an epoxy‐based nanocomposite system were investigated. Chemical functionalization of MWCNTs by acid modification (A‐MWCNTs) and chemical amidation (D‐MWCNTs) was confirmed using Fourier transform infrared spectroscopy and thermogravimetric analysis. It was found that the D‐MWCNTs had a significant effect on the chemorheological behaviors of the epoxy‐based nanocomposite. Compared to the epoxy/A‐MWCNT nanocomposite, the epoxy/D‐MWCNTs nanocomposite showed a significant increase in gel time, as obtained from isothermal rheology measurements. Also, the storage modulus of the diglycidylether of bisphenol F (DGEBF)/D‐MWCNTs nanocomposite was higher than that of the DGEBF/D‐MWCNTs nanocomposite and gradually increased with an increase of frequency. This could be interpreted by the relatively strongly interconnected structure of the D‐MWCNTs in the DGEBF epoxy resin, which arises from the functionalized alkyl groups of the D‐MWCNTs in dispersion phases with the DGEBF epoxy resin. Copyright © 2012 Society of Chemical Industry     

Synthesis and processing of PMMA carbon nanotube nanocomposite foams

Poly(methyl methacrylate) (PMMA) multi-walled carbon nanotubes (MWCNTs) nanocomposites were synthesized by several methods using both pristine and surface functionalized carbon nanotubes (CNTs). Fourier transform infrared (FTIR) spectroscopy was used to characterize the presence and types of functional groups in functionalized MWCNTs, while the dispersion of MWCNTs in PMMA was characterized using scanning electron microscopy (SEM). The prepared nanocomposites were foamed using carbon dioxide (CO₂) as the foaming agent. The cell morphology was observed by SEM, and the cell size and cell density were calculated via image analysis. It was found that both the synthesis methods and CNTs surface functionalization affect the MWCNTs dispersion in the polymer matrix, which in turn profoundly influences the cell nucleation mechanism and cell morphology. The MWCNTs are efficient heterogeneous nucleation agents leading to increased cell density at low particle concentrations. A mixed mode of nucleation mechanism was observed in nanocomposite foams in which polymer rich and particle rich region co-exist due to insufficient particle dispersion. This leads to a bimodal cell size distribution. Uniform dispersion of MWCNTs can be achieved via synergistic combination of improving synthesis methodology and CNTs surface functionalization. Foams from these nanocomposites exhibit single modal cell size distribution and remarkably increased cell density and reduced cell size. An increase in cell density of ∼70 times and reduction of cell size of ∼80% was observed in nanocomposite foam with 1% MWCNTs.     

Effect of amino‐functionalization of multi‐walled carbon nanotubes on the dispersion with epoxy resin matrix

Amino‐functionalization of multiwalled carbon nanotubes (MWCNTs) was carried out by grafting triethylenetetramine (TETA) on the surfaces of MWCNTs through the acid–thionyl chloride way. The amino‐functionalized MWCNTs show improved compatibility with epoxy resin and, as a result, more homogenous dispersion in the matrix. The mechanical, optical, and thermal properties of the amino‐functionalized MWCNT/epoxy composites were also investigated. It was found that introducing the amino‐functionalized MWCNTs into epoxy resin greatly increased the charpy impact strength, glass transition temperature, and initial decomposing temperature of cured epoxy resin. In addition, introducing unfunctionalized MWCNTs into epoxy resin was found greatly depressing the light transmission properties, which would affirmatively confine the application of the MWCNTs/epoxy composites in the future, while much higher light transmittance than that of unfunctionalized MWCNTs/epoxy composites was found for amino‐functionalized MWCNTs/epoxy composites. SEM of the impact cross section and TEM of ultrathin film of the amino‐functionalized MWCNTs/epoxy composites showed that the amino‐functionalized MWCNTs were wetted well by epoxy matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 97–104, 2006     

Rheological properties and fracture toughness of epoxy resin/multi‐walled carbon nanotube composites

Multi‐walled carbon nanotubes (MWCNTs), surface‐treated via chemical functionalization, i.e., oxidation and amidation, were used to reinforce diglycidylether of bisphenol F (DGEBF) epoxy resin. The effects of the functionalization on the dispersion stability, rheological properties, and fracture toughness of DGEBF/MWCNT composites were investigated. The dispersion homogeneity of the MWCNTs in the epoxy matrix improved after functionalization. In addition, isothermal rheology measurements revealed that the DGEBF/dodecyl amine‐functionalized MWCNT (D‐MWCNT) composite had a longer gel time and higher activation energy of cross‐linking than the DGEBF/acid‐treated MWCNT (A‐MWCNT) composite. The fracture toughness of the former was also significantly higher than that of the latter; this resulted from the relatively high dispersion stability of the D‐MWCNTs in the epoxy matrix, owing to the presence of alkyl groups on the D‐MWCNT surface. POLYM. ENG. SCI., 55:2676–2682, 2015. © 2015 Society of Plastics Engineers     

Thermal,mechanical and acoustic damping properties of flexible open‐cell polyurethane/multi‐walled carbon nanotube foams: effect of surface functionality of nanotubes

This article demonstrates the properties of open‐cell flexible polyurethane foams incorporating multi‐walled carbon nanotubes. Three different types of highly functionalized nanotubes having carboxyl, hydroxyl and amide functional groups were synthesized. Neat polyurethane foam and three nanocomposite foams filled with 0.1 wt% of treated nanotubes were prepared. It was found that thermal stability, mechanical properties and acoustic damping were improved significantly by incorporation of small amounts of nanotubes. The nanotubes modified with carboxyl groups were found to have much more influence compared to the other two functional groups, possibly due to better interfacial interaction and improved dispersion. Scanning electron microscopy revealed micro‐cells with average diameters less than 5 µm in the skeleton of foams filled with nanotubes modified with hydroxyl and carboxyl, the formation of which was attributed to the generation of gaseous materials through the reaction with isocyanate. Such micro‐cells were found to be influential in improving mechanical and acoustic damping. Copyright © 2010 Society of Chemical Industry     

Effect of organoclay content on the mechanical properties of ethylene‐vinyl acetate copolymer/ multi‐walled carbon nanotube/organoclay foams

The main objective of this study is to obtain ethylene‐vinyl acetate copolymer (EVA)/multi‐walled carbon nanotube (MWCNT)/organoclay foams with improved mechanical properties without increase of their density, compared with EVA/MWCNT foams. MWCNT content was fixed at 5 phr in this study. To achieve the objective, EVA was melt‐mixed with MWCNTs and organoclays in a bench kneader. And the obtained EVA/MWCNT/organoclay mixtures were mixed with chemical blowing agent and cross‐linking agent in a two roll‐mill. After being mixed in a two roll‐mill, the mixtures were put in a mold and the foams were obtained by compression‐molding. The effect of organoclay content on the mechanical properties and surface resistivity of EVA/MWCNT (5 phr)/organoclay foams was investigated. The addition of 1 phr organoclays to the EVA/MWCNT (5 phr) foams resulted in the improvement of tensile strength, 100% tensile modulus, tear strength, and compression set without increase of the density. However, further increase in content of organoclay (3 phr) leaded to a deterioration of mechanical properties. Therefore, determining the optimal content of organoclay was very important in order to achieve the main objective of this study. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Cure reaction of multi‐walled carbon nanotubes/diglycidyl ether of bisphenol A/2‐ethyl‐4‐methylimidazole (MWCNTs/DGEBA/EMI‐2,4) nanocomposites: effect of carboxylic functionalization of MWCNTs

BACKGROUND: The aim of this work was to study, using differential scanning calorimetry, the effect of carboxylic functionalization of multi‐walled carbon nanotubes (MWCNTs) on the cure reaction of MWCNTs/diglycidyl ether of bisphenol A/2‐ethyl‐4‐methylimidazole (MWCNTs/DGEBA/EMI‐2,4) nanocomposites. This is important for the practical design, analysis and optimization of novel materials processing. RESULTS: Comparing the influence of non‐functionalized MWCNTs and carboxyl‐functionalized MWCNTs, it was found that, at the initial curing stage, both MWCNTs act as catalyst and COOH functionalization of MWCNTs has a catalytic effect on the curing process. Then, at the later curing stage, non‐functionalized MWCNTs prevent the occurrence of vitrification, whereas COOH functionalization of MWCNTs promotes vitrification. Non‐functionalized MWCNTs decrease the degree of curing, as evidenced by lower total heat of reaction and lower glass transition temperatures of nanocomposites compared to neat epoxy; however, COOH functionalization of MWCNTs increases the degree of curing. CONCLUSION: For the development of composites, COOH functionalization of MWCNTs could bring a positive influence to the composite process. Its acceleration of cure could help shorten pre‐cure time or lower pre‐treatment temperature, and its effect of promoting vitrification could help shorten post‐cure time or lower post‐treatment temperature. Copyright © 2009 Society of Chemical Industry     

Polypropylene–nano‐silica nanocomposite foams: mechanisms underlying foamability,and foam microstructure,crystallinity and mechanical properties

We investigate the production and characterization of foams prepared from polypropylene (PP) as well as PP–silica nanocomposites containing different loadings of nano‐silica. This study was carried out to investigate the mechanisms underlying the production of foams with a regular cell structure through the use of nano‐scale fillers. Foaming was carried out in batch mode using an autoclave with CO₂ as the physical blowing agent; high pressures of the order of 14 MPa were achieved through a combination of active pressurization and the use of high foaming temperatures. The resulting PP nanocomposite foams were characterized in detail to quantify the effect of the nano‐silica loading on the foam density and mechanical, morphological and thermal properties. The addition of nano‐silica in PP resulted in the improvement of foam quality – as assessed from the well‐defined and regular cell structures with absence of cell coalescence – as well as an increase in expansion ratio and decrease in foam density. Careful analyses of trends in cell size, cell density and expansion ratio of the foams were correlated with measurements of melt rheology and nano‐filler morphology of the unfoamed specimens in order to identify subtle details regarding the role of silica nanoparticles in improving foam quality. © 2019 Society of Chemical Industry     

Deposition of silver nanoparticles onto human serum albumin‐functionalised multi‐walled carbon nanotubes

To facilitate the design of carbon nanotube (CNT)‐based hybrid materials, a strategic approach for nanotube dispersion in aqueous media is required. This means that the reactants must exhibit certain selectivity towards both the nanotubes and the solvent medium. The main goal of this study was to prepare new bionanomaterials based on human serum albumin (HSA) and multi‐walled CNTs (MWCNTs), under mild conditions and without covalent modification of the nanotubes. Silver nanoparticles (AgNPs) of a controlled particle size, about 2‐nm diameter, were prepared and directly deposited onto the HSA‐functionalised MWCNTs. The characterisation of AgNP/HSA‐MWCNT hybrids prepared was carried out by scanning tunneling microscopy and transmission electron microscopy (TEM). The presence of the AgNPs was corroborated by elemental chemical analysis using TEM‐coupled energy‐dispersive X‐ray spectroscopy. The density of AgNPs coverage is discussed as a function of HSA concentration, the strength of the reducing agent, and the nature of protein employed (HSA vs. bovine serum albumin and rotavirus nucleocapsid protein VP6). © 2012 Canadian Society for Chemical Engineering     

Novel nanocomposite of poly(acrylonitrile‐co‐glycidyl methacrylate) crosslinked with Jeffamine‐functionalized multiwalled carbon nanotubes as gel polymer electrolytes

Multiwalled carbon nanotubes (MWCNTs) were functionalized with α,ω‐diamino poly(propylene oxide) (Jeffamine) of different molecular weights and crosslinked with poly(acrylonitrile‐co‐glycidyl methacrylate) [P(AN‐GMA)] to prepare a novel nanocomposite for applications in gel polymer electrolytes (GPEs). The synthesized copolymer was characterized by ¹H‐NMR, Fourier transform infrared, and thermal analysis. Scanning electron microscope observation revealed that the Jeffamine‐functionalized MWCNTs distributed uniformly in the nanocomposite membrane. The mechanical behaviors of the nanocomposite membranes were investigated. It was found that the crosslinked nanocomposite membranes of P(AN‐GMA) and Jeffamine‐functionalized MWCNTs exhibited much higher mechanical strength than the counterpart nanocomposite obtained by physical blending. Moreover, the weight content and molecular weights of Jeffamine had an effect on the mechanical properties of the nanocomposites. Differential scanning calorimeter measurements showed that the crosslinked nanocomposite membranes were amorphous. GPEs based on the nanocomposite were prepared and characterized by complex impedance measurements. The GPE based on the nanocomposite of P(AN‐GMA) crosslinked with 6 wt % of MWCNTs functionalized by Jeffamine D400 showed an ionic conductivity of about 3.39 × 10^?4 S cm^?1 at 25°C, which is much higher than the counterpart nanocomposite of physically blended P(AN‐GMA) and MWCNTs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Efficient functionalization of multi‐walled carbon nanotubes with p‐aminophenol and their application in the fabrication of poly(amide‐imide)‐matrix composites

The ultrasonically assisted preparation and characterization of poly(amide‐imide) (PAI) composites containing functionalized multi‐walled carbon nanotubes (MWCNTs) are reported. To improve the dispersion in and compatibility with the polymer matrix, the MWCNTs were surface‐modified with p‐aminophenol (p‐AP) under microwave irradiation. The process is fast, one‐pot, easy and results in a high degree of functionalization as well as dispersibility in organic solvents. The p‐AP‐functionalized MWCNTs (MWCNTs‐AP) were analysed by means of field emission and transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction and thermogravimetric analysis (TGA). The results consistently confirm the formation of p‐AP functionalities on MWCNTs which are able to undergo additional reactions, while the structure of the MWCNTs remains relatively intact. MWCNTs‐AP/PAI hybrid films were prepared with various MWCNTs‐AP contents (5–15 wt%) using a solution‐casting technique. Microscopic observations show that the dispersion of the MWCNTs‐AP is improved as a result of the organic groups on the MWCNT surface and functional groups in the PAI structure. The properties of the obtained composites were characterized extensively using the aforementioned techniques. TGA results show that the hybrid films exhibit a good thermal stability. Tensile mechanical testing was performed for the prepared composites, the results of which indicate an increase in the elastic modulus and tensile strength with increasing MWCNTs‐AP content. © 2013 Society of Chemical Industry     

Morphology and tensile properties of crosslinked nanocomposite foams of low‐density polyethylene and poly(ethylene‐co‐vinyl acetate) blends

This paper studies the morphology and tensile properties of nanocomposite foams of blends of low‐density polyethylene (LDPE) and poly(ethylene‐co‐vinyl acetate) (EVA). Preparations of LDPE/EVA nanocomposites were conducted in an internal mixer, and then samples were foamed via a batch foaming method. Morphology of the nanocomposite blends and nanocomposite foams was studied by X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. Morphological observations showed that nanoparticle dispersion in the polymeric matrix was affected by the blend ratio in a way such that EVA‐rich samples had a better dispersion of nanoclay than LDPE‐rich ones. In addition, the tensile properties of the nanocomposite foams were related to different variables such as blend ratio, clay content, and foam density. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

A binder‐free Ir0.4Ru0.6‐oxide/functionalized multi‐walled carbon nanotube electrode for possible applications in supercapacitors

An initial study on a simple and inexpensive method to form an Ir_0.4Ru_0.6‐oxide (MMO) coating onto high‐area plasma functionalized multi‐walled carbon nanotubes (f‐MWCNTs) at the bench‐scale for possible supercapacitor (SC) applications is presented. f‐MWCNT electrodes are prepared in a two‐step process combining the growth of MWCNTs directly onto a 316 stainless steel mesh by thermal‐chemical vapour deposition (t‐CVD), followed by the addition of oxygen‐containing functionalities to their surface by plasma functionalization. The plasma functionalization step is done to: (i) improve electrode wettability and (ii) improve capacitive properties through the addition of pseudocapacitive oxygen functionalities. A simple dip‐dry method is then employed to coat the f‐MWCNTs with the desired MMO coating (Ir_0.4Ru_0.6‐oxide) prepared initially in a liquid precursor mixture. f‐MWCNT electrodes are suspended and dipped into the precursor then heated in air to evaporate the solvent while building the oxide layer. The resulting MMO/f‐MWCNT electrode exhibits excellent stability in 4 mol/L KOH electrolyte, yielding larger specific capacitance values than those obtained on bare f‐MWCNT electrodes; at a charging/discharging current density of 0.5 mA cm^?2, the MMO/f‐MWCNT and f‐MWCNT electrodes achieve specific capacitances of 664 ± 7 and 190 ± 30 F g^?1 in a 3‐electrode cell, respectively. The MMO/f‐MWCNT electrodes show good rate capability performance up to 10 mA · cm^?2 and excellent stability.

     

Preparation of biocompatible multi‐walled carbon nanotubes as potential tracers for sentinel lymph nodes

Carbon nanotubes (CNTs) are capable of traversing cellular membranes by endocytosis and are therefore promising materials for use in imaging and drug delivery. Unfortunately, pristine CNTs are practically insoluble and tend to accumulate inside cells, organs and tissues. To overcome the poor dispersibility and toxicity of pristine CNTs, hydrophilic functionalization of CNTs has been intensively investigated. Water‐soluble multi‐walled carbon nanotubes (MWCNTs) were prepared by in situ polymerization of acrylic acid in a poor solvent for poly(acrylic acid) (PAA). The solvent type influenced the grafted density and chain length of PAA. MWCNTs with a high grafted density of PAA (22 wt%) could be well dispersed in water, NaCl aqueous solution (0.9 wt%) and cell culture media. The in vitro cytotoxicity of these MWCNTs for endothelial cells is reasonably low even at high concentration of PAA‐g‐MWCNT (70 µg mL^?1). The experimental results show that the biocompatibility of these MWCNTs is sufficient for biological applications. PAA‐g‐MWCNTs were successfully utilized for lymph node tracing. Experimental results suggest that PAA‐g‐MWCNTs have potential to be used as a vital staining dye, which may simplify the identification of lymph nodes during surgery. Copyright © 2009 Society of Chemical Industry     

Hyperbranched polyurethane/triethanolamine functionalized multi‐walled carbon nanotube nanocomposites as remote induced smart materials

Triethanolamine functionalized multi‐walled carbon nanotubes (TEA‐f‐MWCNTs)/hyperbranched polyurethane nanocomposites were prepared by the in situ polymerization technique. The functionalization of the MWCNTs was confirmed by Fourier transform infrared spectroscopy and Raman spectroscopy studies. The homogeneous distribution and the strong interfacial interaction of TEA‐f‐MWCNTs with the polyurethane chains were confirmed by transmission electron microscopy and Fourier transform infrared spectroscopy studies, respectively. Significant enhancements of tensile strength (6.5 ? 28.5 MPa) and scratch resistance (3–7 kg) with content of TEA‐f‐MWCNTs (0–2 wt%) were observed. Thermogravimetric analysis showed an increase in thermal stability from 240 to 287 °C by the formation of nanocomposites. X‐ray diffraction and differential scanning calorimetry studies confirmed an increment in the degree of crystallinity of the nanocomposites with increase in TEA‐f‐MWCNT content. The extent of shape recovery as well as recovery speed were enhanced with increase in the output power of the microwave. Thus the studied nanocomposites could be utilized as non‐contact microwave energy tunable shape memory materials. © 2013 Society of Chemical Industry     

Amino functionalization of multiwalled carbon nanotubes by gamma ray irradiation and its epoxy composites

In this paper, γ‐ray radiation technique was utilized to simply functionalize multi‐walled carbon nanotube (MWCNT) with amino groups. The successful amino functionalization of MWCNTs (MWCNTs‐Am) was proven and the physicochemical properties of MWCNTs before and after radiation grafting modifications were characterized using FT‐IR, X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results indicated that the γ‐ray radiation had the visible effects on the surface properties of MWCNTs. The effects of various functionalized MWCNTs on morphological, thermal, and mechanical properties of an epoxy‐based nanocomposite system were investigated. Utilizing in situ polymerization, 1 wt% loading of MWCNT was used to prepare epoxy‐based nanocomposites. Compared to the neat epoxy system, nanocomposites prepared with MWCNT‐Am showed 13.0% increase in tensile strength, 20.0% increase in tensile modulus, and 24.1% increase in thermal decomposition temperature. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Preparation and properties of polyvinyl chloride ultrafiltration membranes blended with functionalized multi‐walled carbon nanotubes and MWCNTs/Fe3O4 hybrids

To investigate the influence of magnetic materials combined with carbon nanotubes (CNTs) as fillers on the membrane properties, multi‐walled carbon nanotubes (MWCNTs) functionalized by mixed acids (V_H2SO4:V_HNO3=3:1) were loaded by Fe₃O₄ through a hydrothermal method. The obtained MWCNTs/Fe₃O₄ hybrids were characterized by X‐ray diffraction (XRD), Infrared spectroscopy (IR) spectrum, and scanning electron microscope (SEM) and then blended with polyvinyl chloride (PVC) to prepare ultrafiltration (UF) membranes through a phase inversion process. Simultaneously, two other UF membranes, PVC blended with acid‐treated MWCNTs and PVC blended with nothing, were also prepared. The results showed that the membrane porosity and mean pore size increased slightly with the addition of fillers. Static contact angle showed that MWCNTs/Fe₃O₄ hybrids improved the hydrophilicity of membrane surface better than the acid‐treated MWCNTs. Pure water flux increased consistently with the hydrophilicity of the membrane surface. SEM and atomic force microscope (AFM) images showed that the MWCNTs/Fe₃O₄ blended membrane formed a relatively complete pore structure throughout the cross‐section and had a rougher top surface. However, the mechanical properties of membranes with fillers were reduced compared with the pristine PVC membrane. The rejections of membranes for Bovine serum albumin (BSA), Bisphenol A (BPA), and Norfloxacin (NOR) showed that MWCNTs/Fe₃O₄ played an important role in trapping pollutants in membrane filtration. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43417.     

Development of water‐blown bio‐based thermoplastic polyurethane foams using bio‐derived chain extender

Water‐blown bio‐based thermoplastic polyurethane (TPU) formulations were developed to fulfill the requirements of the reactive rotational molding/foaming process. They were prepared using synthetic and bio‐based chain extenders. Foams were prepared by stirring polyether polyol (macrodiol), chain extender (diol), surfactant (silicone oil), chemical blowing agent (distilled water), catalyst, and diisocyanate. The concentration of chain extender, blowing agent, and surfactant were varied and their effects on foaming kinetics, physical, mechanical, and morphological properties of foams were investigated. Density, compressive strength, and modulus of foams decrease with increasing blowing agent concentration and increase with increasing chain extender concentration, but are not significantly affected by changes in surfactant concentration. The foam glass‐transition temperatures increase with increasing blowing agent and chain extender concentrations. The foam cell size slightly increases with increasing blowing agent content and decreases upon surfactant addition (without any dependence on concentration), whereas chain extender concentration has no effect on cell size. Bio‐based 1,3‐propanediol can be used successfully for the preparation TPU foams without sacrificing any properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The orientation of carbon nanotubes in poly(ethylene‐co‐octene) microcellular foaming and its suppression effect on cell coalescence

Poly(ethylene‐co‐octene)/multiwall carbon nanotube (PEOc/MWNT) nanocomposites were prepared by a melt blending process. The MWNT's solubility and the transmission electron microscopy (TEM) observation indicated that the MWNT bonded well with a PEOc matrix. This facilitated the orientation of the MWNT when shear and extensional forces were applied to the nanocomposite melts. Microcellular PEOc/MWNT nanocomposite foams were prepared by a rising temperature process using supercritical CO₂ as the blowing agent. Various foaming times were selected to reveal the cell‐structure evolution during the cell growth stage. The obvious cell opening, resulting from cell coalescence, was observed in the cell wall in the neat PEOc foams. When the MWNT was introduced, however, the MWNT tended to orient in the cell wall. Here, as a result of the strain hardening, it acted as a self‐reinforcing element, protecting the cells from destruction during cell growth. Consequently, a dramatic decrease in the open cell content and a still high cell density at long foaming times were obtained in the PEOc/MWNT nanocomposite foams. The present study provides experimental evidence of the vital effects of nanoparticle orientation on cell coalescence. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Conducting polymerized high‐internal‐phase emulsion/single‐walled carbon nanotube nanocomposite foams: Effect of the aqueous‐phase surfactant type on the morphology and conductivity

Poly(styrene‐co‐divinylbenzene)/single‐walled carbon nanotubes (SWCNTs) polymerized high‐internal‐phase emulsion (polyHIPE) nanocomposite foams were successfully synthesized with various types of aqueous‐phase surfactants. The effects of anionic, cationic, nonionic, and mixed surfactants on the morphology and electrical conductivity of the resulting nanocomposite foams were investigated. The use of an anionic surfactant, sodium dodecylbenzesulfonate (SDBS), did not completely result in the typical polyHIPE nanocomposite foam microstructure because of the partial instability of the high‐internal‐phase emulsion. The nanocomposite foams synthesized by nonionic surfactants, that is, Pluronic F127 and Triton X‐100, and the cationic/anionic mixture, cetyltrimethylammonium bromide/SDBS, exhibited the proper morphology, but the resulting nanocomposite foams were electrically insulators. Interestingly, the use of a Gemini‐like surfactant, sodium dioctylsulfosuccinate (SDOSS), significantly improved both the typical morphology and electrical properties of the resulting nanocomposite foams because of the probable stronger interactions of SDOSS molecules with SWCNTs. The typical morphology of the nanocomposite foam synthesized with the SDOSS/F127 mixed surfactant was significantly improved, but the electrical conductivity decreased to some extent compared with the SDOSS‐synthesized nanocomposite foams. This behavior was attributed to an increase in the tunneling length of the electrons between adjacent SWCNTs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43883.