Neutralisation rate controls the self-assembly of pH-sensitive surfactants

dc.contributor.authorHayward, Dominic W.
dc.contributor.authorChiappisi, Leonardo
dc.contributor.authorTeo, Jyh Herng
dc.contributor.authorPrévost, Sylvain
dc.contributor.authorSchweins, Ralf
dc.contributor.authorGradzielski, Michael
dc.date.accessioned2019-11-26T12:08:28Z
dc.date.available2019-11-26T12:08:28Z
dc.date.issued2019-10-14
dc.description.abstractThe degree of ionisation of a weakly acidic surfactant can be continuously modified from nonionic to ionic by adjusting the pH. This property can be used to control the curvature and therefore the morphology of the self-assembled aggregates it forms in solution. Herein, we report the surprising phenomenon, observed in the alkyl ether oligo(ethylene oxide) carboxylate (CH3(CH2)11/13OEO4.5CH2COOH), whereby it is not only the pH but also the neutralisation rate that affects the aggregate morphology. Specifically, when the pH is increased slowly, up to 40 wt% of the surfactant remains in a long-lived vesicle state at high pH. This phenomenon was characterised in detail by small-angle neutron scattering and light scattering techniques. The cause of this phenomenon is thought to be related to a combination of polydispersity and the formation of acid-carboxylate dimers close to the pKa. The transition of these vesicles to the thermodynamically favoured micelles at high pH is inhibited by a high activation energy barrier and therefore only occurs very slowly. Increasing the NaCl concentration eliminates the presence of vesicles at high pH, demonstrating that the activation energy for the vesicle-to-micelle transition depends strongly on electrostatic interactions. These experiments show that the preparation pathway can be used to obtain different self-assembled structures at identical conditions via kinetic control. This phenomenon provides a useful tool for devising formulations where the properties of the system can be altered without changing the composition.en
dc.description.sponsorshipBMBF, 05K16KT1, SANS an funktionalen Soft-Matter Proben während des Herstellungsprozesses und in komplexen Umgebungenen
dc.description.sponsorshipTU Berlin, Open-Access-Mittel - 2019en
dc.identifier.eissn1744-6848
dc.identifier.issn1744-683X
dc.identifier.urihttps://depositonce.tu-berlin.de/handle/11303/10361
dc.identifier.urihttp://dx.doi.org/10.14279/depositonce-9320
dc.language.isoenen
dc.rights.urihttps://creativecommons.org/licenses/by-nc/3.0/en
dc.subject.ddc541 Physikalische Chemiede
dc.subject.othersurfactanten
dc.subject.otherpHen
dc.subject.otherself-assemblyen
dc.subject.otherSANSen
dc.subject.othersmall-angle neutron scatteringen
dc.subject.otherlight scatteringen
dc.titleNeutralisation rate controls the self-assembly of pH-sensitive surfactantsen
dc.typeArticleen
dc.type.versionpublishedVersionen
dcterms.bibliographicCitation.doi10.1039/C9SM00950Gen
dcterms.bibliographicCitation.journaltitleSoft Matteren
dcterms.bibliographicCitation.originalpublishernameRoyal Society of Chemistryen
dcterms.bibliographicCitation.originalpublisherplaceCambridgeen
dcterms.bibliographicCitation.pageend8620en
dcterms.bibliographicCitation.pagestart8611en
dcterms.bibliographicCitation.volume15en
tub.accessrights.dnbfreeen
tub.affiliationFak. 2 Mathematik und Naturwissenschaften>Inst. Chemie>FG Physikalische Chemie / Molekulare Materialwissenschaftende
tub.affiliation.facultyFak. 2 Mathematik und Naturwissenschaftende
tub.affiliation.groupFG Physikalische Chemie / Molekulare Materialwissenschaftende
tub.affiliation.instituteInst. Chemiede
tub.publisher.universityorinstitutionTechnische Universität Berlinen
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