HM Nilsson,B Meany,J Ticey,CF Sun,YH Wang,J Cumings
摘要:
Experiments probing the properties of individual carbon nanotubes (CNTs) and those measuring bulk composites show vastly different results. One major issue limiting the results is that the procedures required to separate and test CNTs introduce contamination that changes the properties of the CNT. These contamination residues often come from the resist used in lithographic processing and the surfactant used to suspend and deposit the CNTs, commonly sodium dodecyl sulfate (SDS). Here we present ammonium laurate (AL), a surfactant that has previously not been used for this application, which differs from SDS only by substitution of ionic constituents but shows vastly cleaner depositions. In addition, we show that compared to SDS, AL-suspended CNTs have greater shelf stability and more selective dispersion. These results are verified using transmission electron microscopy, atomic force microscopy, ζ-potential measurements, and Raman and absorption optical spectroscopy. This surfactant is simple to prepare, and the nanotube solutions require minimal sonication and centrifugation in order to outperform SDS.
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DOI:
10.1021/acs.langmuir.5b01175
被引量:
年份:
2015
摘要:
Thermal behaviors of 11-layer Langmuir–Blodgett (LB) films of the double long-chain compounds of octadecylammonium laurate (ODALA), octadecylammonium octadecanoate (ODASA) and octadecylammonium tetracosanoate (ODATA) have been investigated by Fourier transform infrared spectroscopy. The temperature-dependent infrared spectra show that thermal stability of the three kinds of LB films depends upon the length of the hydrocarbon chain. The LB film of ODALA undergoes an order–disorder transition in the temperature range of 50–65 °C. In contrast, the ODATA LB film has the phase transition temperature range of 80–90 °C. Of particular interest is that both ODASA and ODATA LB films have nearly the same phase transition temperature range of 80–90 °C, indicating that the replacement between tetracosanoic acid and stearic acid has little effect on the thermal stability of the two compounds. The above observations suggest that the effective length of the alkyl chains, which is determined by the component with a shorter chain in the double long-chain compounds, has a dominant influence on the thermal stability. It is very likely that the whole chain of the shorter chain component such as octadecylamine in ODATA has contribution to the thermal stability while only the effective length of the longer alkyl chain component gives a significant effect.
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关键词:
Infrared spectroscopy Thermal behavior Octadecylammonium laurate Octadecylammonium octadecanoate Octadecylammonium tetracosanoate
DOI:
10.1016/j.vibspec.2009.02.001
被引量:
年份:
2009
W Seangyen,P Prapainainar,P Sae-Oui,S Loykulnant,P Dittanet
摘要:
In-situ silica nanoparticles with ammonium laurate surfactant in natural rubber latex composites were characterized to describe the reinforcement mechanism in enhanced mechanical properties. In-situ sol-gel method was introduced to generate silica nanoparticles in natural rubber latex using a mole ratio of water-to-TEOS of 28.9 stirring at room temperature for 24 hours. The addition and effect of adding ammonium laurate surfactant for enhancing dispersion and compatibility between silica nanoparticles and rubber matrix was also studied. The natural rubber latex was then vulcanized by electron beam radiation at 200 kGy. The silica content in rubber composites made in-situ, was analyzed by TGA, showed an increase from 3.08 phr to 8.92 phr, corresponding to addition of TEOS amounts of 10 phr to 30 phr, respectively. The dispersion of silica nanoparticles in rubber matrix with ammonium laurate surfactant was improved and exhibited less aggregation than rubber composites absent of ammonium laurate surfactant as evidenced by SEM-EDX. The increase of silica content in rubber composites exhibited lower swelling ratio and higher crosslink density when compared with neat natural rubber. Also, the modulus at 100% and 300% strain also increased with increasing silica nanoparticles incorporation in contrast to tensile strength.
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关键词:
TEOS Surfactant Sol-Gel Method In Situ Silica&tn=SE_baiduxueshu_c1gjeupa&ie=utf-8" target="_blank">In Situ Silica Natural Rubber Composites
DOI:
10.4028/www.scientific.net/KEM.821.74
年份:
2019
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