Synthesis, characterization and applications of azo-containing photodestructible surfactants

Dunkin, Ian R.; Gittinger, Andreas; Sherrington, David C.; Whittaker, Paul

doi:10.1039/p29960001837

Cited by 34 publications

(49 citation statements)

References 25 publications

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“…Among them, phenylazosulfonate, as shown in Figure 3, is a very interesting photosensitive group that can be changed from a negatively charged sulfonate to a positively charged diazo, and then to a neutral phenol derivative, by UV-light irradiation. [33,34] This great polarity variation has provided the surfactant with abundant applications in materials science, such as controllable surface tension and photocontrollable emulsifiers in emulsion polymerization, [35] photosensitive gelatin, [36] and photoinduced phase separation. [37] A similar concept can be extended to prepare photoresponsive amphiphilic polymers.…”

Section: Photoirradiated Irreversible Methodsmentioning

confidence: 99%

Tuning the Amphiphilicity of Building Blocks: Controlled Self‐Assembly and Disassembly for Functional Supramolecular Materials

2009

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Amphiphilicity is one of the molecular bases for self‐assembly. By tuning the amphiphilicity of building blocks, controllable self‐assembly can be realized. This article reviews different routes for tuning amphiphilicity and discusses different possibilities for self‐assembly and disassembly in a controlled manner. In general, this includes irreversible and reversible routes. The irreversible routes concern irreversible reactions taking place on the building blocks and changing their molecular amphiphilicity. The building blocks are then able to self‐assemble to form different supramolecular structures, but cannot remain stable upon loss of amphiphilicity. Compared to the irreversible routes, the reversible routes are more attractive due to the good control over the assembly and disassembly of the supramolecular structure formed via tuning of the amphiphilicity. These routes involve reversible chemical reactions and supramolecular approaches, and different external stimuli can be used to trigger reversible changes of amphiphilicity, including light, redox, pH, and enzymes. It is anticipated that this line of research can lead to the fabrication of new functional supramolecular assemblies and materials.

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Section: Photoirradiated Irreversible Methodsmentioning

confidence: 99%

Tuning the Amphiphilicity of Building Blocks: Controlled Self‐Assembly and Disassembly for Functional Supramolecular Materials

2009

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“…This lowenergy radiation should be harmless to proteins. Another approach has been to insert the light-sensitive diazosulfonate group between the polar head group and the tail of an anionic surfactant (55)(56)(57). As can be seen from Scheme 17, these surfactants are also similar in structure to the commonly used ABS.…”

Section: Uv-labile Surfactantsmentioning

confidence: 96%

Cleavable surfactants

Hellberg

Bergström

Holmberg

2000

J Surfact & Detergents

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Cleavable surfactants are of interest for several reasons. Above all, the development of surfactants with weak bonds deliberately built into the structure is driven by the need for improved biodegradability of amphiphiles. The breakdown may be catalyzed by enzymes, and biodegradation would be the normal mechanism in sewage plants. Alternatively, the surfactant may degrade by chemical means, e.g., induced by acid, alkali, ultraviolet (UV) light, heat, or ozone. Acid-and alkali-labile surfactants have attracted particular attention, and there is often a compromise between required stability at one stage and ease of breakdown at a subsequent stage. The paper reviews the main routes used to prepare cleavable surfactants and points out advantages and disadvantages of the different approaches. Emphasis is placed on the development during recent years. Cyclic and acyclic acetals, ketals, and ortho esters are the most important types of bonds for the preparation of acid-labile surfactants, whereas alkali-labile amphiphiles usually are based on ester bonds. The ester bond approach has been particularly important for cationic surfactants, and so-called ester quats have rapidly taken a large share of the traditional market for quats. Betaine esters constitute a special class of ester with very pronounced pH dependence. UV-labile surfactants based, for instance, on an azo bond, offer promise for the future.Paper no. S1174 in JSD 3, 81-91 (January 2000). KEY WORDS: Acetal, betaine ester, choline ester, cleavable surfactant, ester quat, isethionate ester, ketal, labile surfactant, ortho ester, UV degradation. SCHEME 17 SCHEME 16amples of environmentally benign amphiphiles. These surfactants, which contain unsaturated bonds, break down easily during ozonization of water, which is a water purification process of growing importance (64).

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“…Extensive studies involving an anionic photolyzable surfactant, sodium 4-hexylphenylazosulfonate (C 6 PAS), showed that UV light can provoke the breakdown of microemulsions formulated from mixtures with inert Aerosol-OT [19,20]. Photolysis of C 6 PAS switches the hydrophilic surfactant into insoluble hydrophobic components [19][20][21][22][23][24][25][26][27][28]. As outlined in Supporting material, there are two dominant photoproducts: the nonsurface active hexylbenzene and the weakly surface-active 4-hexylphenol.…”

Section: Introductionmentioning

confidence: 99%