A new
series of gemini quaternary ammonium surfactants containing
amide groups with the formula C
n
H2n+1CONH(CH2)2N+(CH3)2(CH2)2 N+(CH3)2(CH2)2NHCOC
n
H2n+1·2CH3CO3
– (n = 11,
13, 15, 17) have been synthesized by the using green reagent dimethyl
carbonate. The structures of these surfactants were confirmed by Fourier
transform infrared spectroscopy, 1H NMR, 13C
NMR, and mass spectra. Their surface activities and aggregation properties
were investigated by surface tension, conductivity, steady-state fluorescence,
dynamic light scattering, and transmission electron microscope measurements.
The results show that these synthesized gemini quaternary ammonium
surfactants reduce the surface tension of water to a minimum value
of 28.21 mN·m–1 at a concentration of 0.256
mmol·kg–1 and self-assemble spontaneously into
double layer aggregates which are mostly single-room vesicles and
multilamellar vesicles. Furthermore, with increasing alkyl chain length,
their critical micelle concentration values and the degree of counterion
binding (β) decrease; and the spontaneous tendency of vesicle
formation and the micellar aggregation numbers (N
m) increase. They are also found to be effective corrosion
inhibitors for A3 steel in acid solution.
A group of Gemini quaternary ammonium surfactants with the formula C
n
H
2
n
+1
CONH(CH
2
)
2
N
+
(CH
3
)
2
(CH
2
)
2
N
+
(CH
3
)
2
(CH
2
)
2
NHCOC
n
H
2
n
+1
· 2Y (
n
= 11, 13 and 15, Y = HCOO
−
, CH
3
COO
−
and CH
3
CHOHCOO
−
) have been synthesized by a counterion conversion process and characterized by Fourier transform infrared spectroscopy and mass spectroscopy. Their adsorption and self-aggregation properties are investigated by surface tension, conductivity, dynamic light scattering and transmission electron microscopy (TEM) measurements. The results show that these surfactants reduce the surface tension of water to a minimum value of 26.51 mN m
−1
at a concentration of 5.72 × 10
−2
mmol l
−1
. Furthermore, the increased alkyl chain length of the carboxylic counterions leads to the increased critical micelle concentration, the decreased degree of counterion binding (
β
) and the decreased self-assembly tendency, but the minimum area per surfactant molecule (
A
min
) adsorbed at the air–aqueous solution are similar. TEM images reveal that these surfactants self-assemble spontaneously into aggregates with vesicle or bilayer structures. It is also found that they have superior antibacterial activity at a concentration of 0.1 g l
−1
. The high surface activity and high antibacterial activity of the Gemini quaternary ammonium salt surfactants containing different carboxylic counterions bring more possibilities for the application in the field of biomedicine.
The huge advantages of intelligent vehicles (IVs) in improving road safety and operating efficiency have become a research focus in the industry. IVs have made significant progress in recent years, but it is still face great challenges in order to be accepted by users on a large scale. In this regard, the authors propose that the research of IVs can be developed along the lines of safety, comfort and economy, gradually overcoming existing dilemmas. First of all, security is the most basic requirement of IVs. The authors sort out the key technologies and challenges of the basic architecture of IVs, and propose existing attack and defences strategies for IVs information security technology. Secondly, comfort is more about people's subjective feelings. From two aspects of physiological comfort and psychological comfort, the paper studies the anthropomorphic decision-making to overcome the mechanized speed control, human computer interaction design, personalized driving style and ethical decision-making methods. Then, aiming at the micro-and macro-levels of economy, it outlines technologies such as economic driving behavioural, collaborative control of people, vehicles and roads and IVs sharing. Finally, the authors summarized the challenges and future development directions in the three stages of IVs development.
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