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A simple and effective emulsion method for the dispersion of carbon nanotubes (CNTs) in waterborne polyurethane (WPU) is reported. WPU emulsions containing reactive CNTs are synthesized by in situ polymerization. During the emulsification process, a part of emulsion particles (EPs) grow and form at the reactive sites of CNTs. The CNT bundle can be separated by the growth and formation of EPs, forming individually suspended CNTs. With the aid of EPs, CNTs can be coated by EPs and easily dispersed in emulsions. After drying, CNTs are uniformly dispersed in the WPU matrix and a low percolation threshold is achieved at 0.132 vol.% CNT content. After addition of only 1, 2, and 3 wt.% CNTs, the tensile strength is greatly improved by about 128%, 179%, and 203% from 14.8 MPa of the pure WPU to 33.8, 41.3, and 44.8 MPa, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT Carbon nanotube (CNT)/styrene-ethylene-butylene-styrene (SEBS) composites were prepared via a sequential process of (electrostatic adsorption assisted dispersion)-plus-(melt mixing). It was found that CNTs were uniformly embedded in SEBS matrix and a low percolation threshold was achieved at the CNT concentration of 0.186 vol %. According to thermal gravimetric analysis, the temperatures of 20% and 50% weight loss were improved from 316°C and 352°C of pure SEBS to 439°C and 463°C of the 3 wt % CNT/SEBS composites, respectively. Meanwhile, the tensile strength and elastic modulus were improved by about 75% and 181.2% from 24 and 1.6 MPa of pure SEBS to 42 and 4.5 MPa of the 3 wt % CNT/SEBS composite based on the tensile tests, respectively. Importantly, this simple and low-cost method shows the potential for the preparation of CNT/polymer composite materials with enhanced electrical, mechanical properties, and thermal stability for industrial applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40227. [ABSTRACT FROM AUTHOR]

Abstract: The uniform dispersion of carbon nanotubes (CNTs) was achieved in the styrene–ethylene–butylene–styrene (SEBS) coated by liquid bisphenol A bis(diphenyl phosphate) (BDP), a halogen-free flame retardant. It was found that most of CNTs existed in a filamentous stretched state. Compared with pure SEBS, the tensile strength and elastic modulus of the SEBS/3wt.% CNTs composite with 5wt.% BDP (SEBS-3), were increased by 114% and 225%, respectively. The temperature of 50% weight loss under air condition increased from 351°C of pure SEBS to 437°C of the SEBS-3. Meanwhile, the limited oxygen index value and UL-94 tests of the SEBS-3 reached 25.5% and V-0, respectively. More importantly, this method endowed the SEBS/BDP/CNT composites with the good mechanical and flame-retardant properties, broadening their scope of application, reducing their cost. [Copyright &y& Elsevier]

Abstract: The uniform dispersion of carbon nanotubes (CNTs) in poly(ethylene terephthalate) (PET) was achieved by the liquid bisphenol A bis(diphenyl phosphate) (BDP) assisted pre-dispersion melt mixing. Most of the CNTs existed in a filamentous stretched state and a percolation threshold was achieved at 0.28 vol.% CNTs. In addition, the uniformly dispersed CNTs, acting as a framework to support the char produced by the oxidation of the PET and BDP, inhibited the vigorous bubbling process during combustion. The char adhering to the CNTs lowered their heat-transfer efficiency and made the CNT network layer more compact. Thus, the flame-retardant property was significantly improved since the network layer consisted of CNTs and chars, acting as a heat shield, more effectively reduced the exposure of the PET resin to the external air and heat feedback of the heat flux. [Copyright &y& Elsevier]

The uniform dispersion of multi-wall carbon nanotubes (MWNTs) in waterborne polyurethane (WPU) matrix was achieved by in-situ polymerization and latex particles assisted dispersion, endowing the MWNT/WPU composite film with the enhanced tensile strength, elongation at break and thermal stability. Compared with pure WPU, the breaking strength, elongation at break and initial decomposition temperature of the MWNT/WPU composite were increased by 69.6%, 16.4% and 130 °C, respectively. The decomposition amount at 400 °C of MWNT/WPU composite is only about half that of pure WPU. The latex particles assisted dispersion also effectively improved the exposure rate of MWNTs, making it easier for MWNTs to contact the target gas molecules. Increased exposure rate and uniform dispersion of MWNTs, and rich functional groups of WPU improved the gas sensing performance, making the response of the flexible MWNT/WPU to O 3 be 4.1 times of the responses of pure MWNTs. The limit of detection for O 3 reached 38.4 ppb. The enhanced mechanical properties endowed the flexible MWNT/WPU composite with the high bending stability and long-term stability. After one month, the response of the MWNT/WPU was changed by 3% and the responses decreased by no more than 10% after bending 5000 times. [Display omitted] • The uniform dispersion of MWNTs in WPU matrix was achieved by in-situ polymerization and latex particles assisted dispersion. • The evenly dispersed MWNTs endowed the MWNT/WPU composite with the enhanced mechanical and thermal properties. • Increased exposure rate of MWNTs and rich functional groups of WPU improved the gas sensing performance of flexible MWNT/WPU sensor. • The response of flexible MWNT/WPU was changed by 3% after one month and the responses decreased by no more than 10% after bending 5000 times. [ABSTRACT FROM AUTHOR]

Inspired by the enhanced gas-sensing performance by the one-dimensional hierarchical structure, one-dimensional hierarchical polyaniline/multi-walled carbon nanotubes (PANI/CNT) fibers were prepared. Interestingly, the simple heating changed the sensing characteristics of PANI from p-type to n-type and n-type PANI and p-type CNTs form p–n hetero junctions at the core–shell interface of hierarchical PANI/CNT composites. The p-type PANI/CNT (p-PANI/CNT) and n-type PANI/CNT (n-PANI/CNT) performed the higher sensitivity to NO2 and NH3, respectively. The response times of p-PANI/CNT and n-PANI/CNT to 50 ppm of NO2 and NH3 are only 5.2 and 1.8 s, respectively, showing the real-time response. The estimated limit of detection for NO2 and NH3 is as low as to 16.7 and 6.4 ppb, respectively. After three months, the responses of p-PANI/CNT and n-PANI/CNT decreased by 19.1% and 11.3%, respectively. It was found that one-dimensional hierarchical structures and the deeper charge depletion layer enhanced by structural changes of PANI contributed to the sensitive and fast responses to NH3 and NO2. The formation process of the hierarchical PANI/CNT fibers, p–n transition, and the enhanced gas-sensing performance were systematically analyzed. This work also predicts the development prospects of cost-effective, high-performance PANI/CNT-based sensors. [ABSTRACT FROM AUTHOR]

The table of contents entry A sensing scheme based on internet of thing to detect O 3 at room temperature is achieved by tailoring the sensing performances of MWCNTs with non-covalent functionalization. The sensor array based on MWCNTs makes the discriminative and sensitive detection of O 3 possible within 30 s at room temperature. • Multi-walled carbon nanotubes were noncovalently functionalized to develop the chemiresistive sensor array with the tailoring responses. • The sensor array displayed the excellent endurance to humidity and the good long-term stability. • The sensor array can identify O 3 , NO 2 and other analytes within 30 s in the real-world detection. • This method may lead to a valuable application based on internet of thing for the low-cost monitoring of gaseous pollutants. Carbon nanotubes are considered as one of the leading candidate materials for the high-performance, internet of thing (IoT)-based gas sensor operating at room temperature. Multi-walled carbon nanotubes (MWCNTs) as a sensing platform were noncovalently functionalized by six kinds of functional modifiers to discriminatively detect ozone (O 3). Compared with the MWCNTs, the responses of functionalized MWCNTs to 5 ppm of O 3 were improved by about 68.8–258.3% and the highest response reached 34.4%. The maximum response of functionalized MWCNTs to 100% relative humidity was just 5.6%, displaying the excellent endurance to humidity. After two months, the decrease in the response value of the most sensitive sensor to O 3 was no more than 15%, showing the good long-term stability. Furthermore, the sensor array was optimized according to principal component analysis and achieved the discriminative detection of six analytes in 30 s at room temperature. For the most sensitive sensor of the sensor array, the theoretical limit of detection for O 3 is determined to be 24.2 ppb. Importantly, it could be coupled with the image recognition and cloud computing for a rapid diagnostic detection of gaseous pollutants under the background of the rapid development of IoT. [ABSTRACT FROM AUTHOR]

Manganese oxides have been proved to be a promising low-cost electrocatalyst for oxygen reduction reaction (ORR) and a critical step in systems of zinc-air batteries, however, which is limited by the poor electrical conductivity. In this paper, we introduce carbon nanotubes (CNTs) as conductive supports to further prepare manganese oxide/CNTs composites with bifunctional electrocatalytic activity by the incorporation of redox and calcination two-step approach. Meanwhile, the effects of mass ratio, calcination temperature and oxidation degree on the oxygen reduction reaction (ORR) activity of the composites were studied. The electrocatalytic results showed that the MnO 2 /CNTs exhibited better electrocatalytic activity than that of manganese dioxide (MnO 2) and CNTs when the mass ratio of CNTs to MnO 2 was 60%. After calcination at 400 °C and reduction treatment of sulfur (S) to adjust the surface oxygen vacancy concentration and Mn3+ content, the ORR and oxygen evolution reaction (OER) bifunctional catalytic activity of the obtained MnO X /CNTs -400 was significantly enhanced. The ORR half-wave potential (E 1/2) and bifunctional potential difference (ΔE OER-ORR) between the ORR half-wave potential and OER potential at 10 mA cm−2 were 0.77 V and 0.92 V, respectively, due to the introducing of highly conductive CNTs, increase of Mn3+ content and oxygen vacancy concentration. Furthermore, the composite also exhibits higher methanol tolerance and long-term stability than the commercial Pt/C catalyst, which provided a class of highly efficient ORR/OER bifunctional electrocatalysts with great energy potential. [Display omitted] • MnO 2 /CNTs composites were synthesized using CNTs as the conductive carriers. • Heat treatment enhanced the coupling interaction between MnO 2 and CNTs. • High temperature desulfurization increased the oxygen vacancy and Mn3+ concentration. • MnO X /CNTs -400 exhibited high bifunctional electrocatalytic activity and stability. [ABSTRACT FROM AUTHOR]