Aggregation and microstructure in aqueous solutions of the nonionic surfactant C12E8

D. Danino; Y. Talmon; R. Zana

doi:10.1006/jcis.1996.4599

Aggregation and microstructure in aqueous solutions of the nonionic surfactant C₁₂E₈

D. Danino, Y. Talmon, R. Zana^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

58 Scopus citations

Abstract

Mixtures of water and of the nonionic surfactant C₁₂E₈ (octaoxyethyleneglycol monododecylether) have been investigated by time-resolved fluorescence quenching (TRFQ) and transmission electron microscopy at cryogenic temperature (cryo-TEM) to obtain information on the size and shape of the surfactant aggregates and on the microstructure of the mixtures. The studies were performed at surfactant contents and temperatures where the micelles grew significantly and also where the systems undergo phase transitions from micellar-to-cubic upon increasing surfactant content or decreasing temperature and from cubic-to-hexagonal-to-micellar upon increasing temperature. No rapid change or discontinuity was observed in the variation of the aggregation number with the surfactant content or temperature upon crossing the micellar-to cubic- phase boundary nor at the approach of the hexagonal phase from the cubic phase. The results confirmed that the cubic phase consists of spheroidal micelles forming a three-dimensional array. The aggregation numbers at high surfactant content or temperature can be much larger than that of the minimum spherical micelle for a surfactant with a dodecyl chain, suggesting that the micelles should be anisotropic. However, cryo-TEM showed that in the micellar phase the micelles are always spheroidal. These apparently inconsistent results are explained in terms of a partial mixing of the surfactant dodecyl chains and octaoxyethylene head groups which allows for spheroidal micelles of aggregation number much larger than for a surfactant with a dodecyl chain. The results show extensive exchange of material at 40°C, taking place most likely via temporary merging of micelles in micelle clusters then present in the system.

Original language	English
Pages (from-to)	170-179
Number of pages	10
Journal	Journal of Colloid and Interface Science
Volume	186
Issue number	1
DOIs	https://doi.org/10.1006/jcis.1996.4599
State	Published - 1 Feb 1997
Externally published	Yes

Keywords

Cubic-to-hexagonal phase transition
Micellar-to-cubic phase transition
Micelle aggregation number
Nonionic surfactants
Shape and dynamics
Time-resolved fluorescence quenching cryo-TEM

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10.1006/jcis.1996.4599

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title = "Aggregation and microstructure in aqueous solutions of the nonionic surfactant C12E8",

abstract = "Mixtures of water and of the nonionic surfactant C12E8 (octaoxyethyleneglycol monododecylether) have been investigated by time-resolved fluorescence quenching (TRFQ) and transmission electron microscopy at cryogenic temperature (cryo-TEM) to obtain information on the size and shape of the surfactant aggregates and on the microstructure of the mixtures. The studies were performed at surfactant contents and temperatures where the micelles grew significantly and also where the systems undergo phase transitions from micellar-to-cubic upon increasing surfactant content or decreasing temperature and from cubic-to-hexagonal-to-micellar upon increasing temperature. No rapid change or discontinuity was observed in the variation of the aggregation number with the surfactant content or temperature upon crossing the micellar-to cubic- phase boundary nor at the approach of the hexagonal phase from the cubic phase. The results confirmed that the cubic phase consists of spheroidal micelles forming a three-dimensional array. The aggregation numbers at high surfactant content or temperature can be much larger than that of the minimum spherical micelle for a surfactant with a dodecyl chain, suggesting that the micelles should be anisotropic. However, cryo-TEM showed that in the micellar phase the micelles are always spheroidal. These apparently inconsistent results are explained in terms of a partial mixing of the surfactant dodecyl chains and octaoxyethylene head groups which allows for spheroidal micelles of aggregation number much larger than for a surfactant with a dodecyl chain. The results show extensive exchange of material at 40°C, taking place most likely via temporary merging of micelles in micelle clusters then present in the system.",

keywords = "Cubic-to-hexagonal phase transition, Micellar-to-cubic phase transition, Micelle aggregation number, Nonionic surfactants, Shape and dynamics, Time-resolved fluorescence quenching cryo-TEM",

author = "D. Danino and Y. Talmon and R. Zana",

note = "Funding Information: The work done at the Technion was supported in part by grants from the United States—Israel Binational Science Foundation (BSF), Jerusalem, and from the Fund for the Promotion of Research at the Technion. The authors thank Ms. Berta Shdemati and Judith Schmidt for expert technical help and assistance. R.Z. thanks the Mission des Relations Internationales (CNRS, France) for partial financing of his stay at the Technion.",

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doi = "10.1006/jcis.1996.4599",

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N2 - Mixtures of water and of the nonionic surfactant C12E8 (octaoxyethyleneglycol monododecylether) have been investigated by time-resolved fluorescence quenching (TRFQ) and transmission electron microscopy at cryogenic temperature (cryo-TEM) to obtain information on the size and shape of the surfactant aggregates and on the microstructure of the mixtures. The studies were performed at surfactant contents and temperatures where the micelles grew significantly and also where the systems undergo phase transitions from micellar-to-cubic upon increasing surfactant content or decreasing temperature and from cubic-to-hexagonal-to-micellar upon increasing temperature. No rapid change or discontinuity was observed in the variation of the aggregation number with the surfactant content or temperature upon crossing the micellar-to cubic- phase boundary nor at the approach of the hexagonal phase from the cubic phase. The results confirmed that the cubic phase consists of spheroidal micelles forming a three-dimensional array. The aggregation numbers at high surfactant content or temperature can be much larger than that of the minimum spherical micelle for a surfactant with a dodecyl chain, suggesting that the micelles should be anisotropic. However, cryo-TEM showed that in the micellar phase the micelles are always spheroidal. These apparently inconsistent results are explained in terms of a partial mixing of the surfactant dodecyl chains and octaoxyethylene head groups which allows for spheroidal micelles of aggregation number much larger than for a surfactant with a dodecyl chain. The results show extensive exchange of material at 40°C, taking place most likely via temporary merging of micelles in micelle clusters then present in the system.

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Aggregation and microstructure in aqueous solutions of the nonionic surfactant C₁₂E₈

Abstract

Keywords

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