Synthesis and Properties of pH‐Dependent Gemini Surfactants Containing Multiple Carboxyl Groups

Abstract

A series of Gemini surfactants N,N″‐dialkyl‐N,N′,N″‐tripropionate diethylenetriamine (referred as DTPDT‐n, where n is the length of the hydrocarbon chain, n = 10, 12, 14) were synthesized, which have three carboxylic head‐groups and two hydrophobic alkane chains. The products were characterized by means of nuclear magnetic resonance and mass spectrometry. The physicochemical properties of DTPDT‐n surfactants with different hydrocarbon chain lengths were studied such as isoelectric point, surface activities, emulsifying properties, and foam properties. It is showed that these compounds exhibit pH‐dependent protonation‐deprotonation behavior. The isoelectric points of DTPDT‐n surfactants are between 3.40 and 10.90. The critical micellar concentration (cmc) of all three surfactants are lower than the corresponding monomeric surfactants (single head group, single‐chain), especially DTPDT‐14, whose cmc can reach 2.29 × 10−5 mol/L. With an increase in the length of the alkyl chain, the solubility of the surfactants decreases and the surface tension of the three surfactants at cmc increases. In consideration of pH, all of three surfactants appear better emulsifying capacity and foaming property under weak alkaline conditions. DTPDT‐14 has the best performance of emulsifying capacity among the three surfactants. DTPDT‐10 has excellent foaming ability and foam stability.

Synthesis and Properties of Two Amino Carboxylic Acid Gemini Surfactants

“…The surface tension value (γ cmc ) and cmc of the DDPED surfactant (two carboxyl groups) are smaller than that of DTPTT surfactant (four carboxyl groups). Compared the DTPDT surfactant (N,N″‐didodecyl‐N,N′,N″‐tripropionate diethylenetriamine) which have three carboxylic groups (Qiao et al, 2020), the surface activity of the DDPED surfactant which have two carboxyl groups is better than that of the homologous surfactants with more carboxyl groups. With the number of carboxyl groups decreasing, the hydrophobicity of the surfactant is increased.…”

“…The emulsion stability of DTPTT is inferior to those of Tween 80 and Span 80. Compared with the DTPDT surfactant which have three carboxylic groups (Qiao et al, 2020), the emulsion stability of the DTPTT surfactant is the same as the DTPDT. According to the hydrophilic–lipophilic balance (HLB) theory, the DDPED can be used as an O/W emulsifier.…”

“…The Gemini surfactants emulsified the liquid paraffin in water. The emulsion stability was estimated by the time of water separation from the emulsion (Qiao et al, 2020).…”

“…Some Gemini surfactants were prepared by addition reaction of ethylenediamine with methyl acrylate. The cmc is lower, and the surface activity, foaming, and wetting forces are better (Qiao et al, 2020; Tsubone et al, 2003b).…”

The BESIII physics programme

“…These states, which include the Y (4260) [117], the Y (4360) [89,118], and the Y (4660) [89], have strong couplings to cc charmonium final states, in contrast to conventional vector cc charmonium states in the same energy region (such as ψ(4040), ψ(4160), and ψ(4415)) that dominantly couple to pairs of D mesons [54]. These Y states are candidates for a variety of types of nonstandard hadrons including: molecules [104,[119][120][121]; diquark-diantiquarks [122,123]; QCD-hybrids [124,125]; and hadrocharmonia [126] (See Fig. 4).…”