PH-sensitive self-propelled motion of oil droplets in the presence of cationic surfactants containing hydrolyzable ester linkages

Taisuke Banno, Rie Kuroha, Taro Toyota

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

Self-propelled oil droplets in a nonequilibrium system have drawn much attention as both a primitive type of inanimate chemical machinery and a dynamic model of the origin of life. Here, to create the pH-sensitive self-propelled motion of oil droplets, we synthesized cationic surfactants containing hydrolyzable ester linkages. We found that n-heptyloxybenzaldehyde oil droplets were self-propelled in the presence of ester-containing cationic surfactant. In basic solution prepared with sodium hydroxide, oil droplets moved as molecular aggregates formed on their surface. Moreover, the self-propelled motion in the presence of the hydrolyzable cationic surfactant lasted longer than that in the presence of nonhydrolyzable cationic surfactant. This is probably due to the production of a fatty acid by the hydrolysis of the ester-containing cationic surfactant and the subsequent neutralization of the fatty acid with sodium hydroxide. A complex surfactant was formed in the aqueous solution because of the cation and anion combination. Because such complex formation can induce both a decrease in the interfacial tension of the oil droplet and self-assembly with n-heptyloxybenzaldehyde and lauric acid in the aqueous dispersion, the prolonged movement of the oil droplet may be explained by the increase in heterogeneity of the interfacial tension of the oil droplet triggered by the hydrolysis of the ester-containing surfactant.

Original languageEnglish
Pages (from-to)1190-1195
Number of pages6
JournalLangmuir
Volume28
Issue number2
DOIs
Publication statusPublished - 2012 Jan 17
Externally publishedYes

Fingerprint

Cationic surfactants
linkages
esters
Esters
Oils
oils
surfactants
Sodium Hydroxide
lauric acid
sodium hydroxides
fatty acids
Fatty acids
Surface-Active Agents
Surface tension
hydrolysis
Hydrolysis
interfacial tension
Surface active agents
Fatty Acids
Sodium

ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Science(all)
  • Spectroscopy

Cite this

PH-sensitive self-propelled motion of oil droplets in the presence of cationic surfactants containing hydrolyzable ester linkages. / Banno, Taisuke; Kuroha, Rie; Toyota, Taro.

In: Langmuir, Vol. 28, No. 2, 17.01.2012, p. 1190-1195.

Research output: Contribution to journalArticle

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