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

Hayward, Dominic W.; Chiappisi, Leonardo; Teo, Jyh Herng; Prévost, Sylvain; Schweins, Ralf; Gradzielski, Michael

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

dc.contributor.author	Hayward, Dominic W.
dc.contributor.author	Chiappisi, Leonardo
dc.contributor.author	Teo, Jyh Herng
dc.contributor.author	Prévost, Sylvain
dc.contributor.author	Schweins, Ralf
dc.contributor.author	Gradzielski, Michael
dc.date.accessioned	2019-11-26T12:08:28Z
dc.date.available	2019-11-26T12:08:28Z
dc.date.issued	2019-10-14
dc.description.abstract	The 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.sponsorship	BMBF, 05K16KT1, SANS an funktionalen Soft-Matter Proben während des Herstellungsprozesses und in komplexen Umgebungen	en
dc.description.sponsorship	TU Berlin, Open-Access-Mittel - 2019	en
dc.identifier.eissn	1744-6848
dc.identifier.issn	1744-683X
dc.identifier.uri	https://depositonce.tu-berlin.de/handle/11303/10361
dc.identifier.uri	http://dx.doi.org/10.14279/depositonce-9320
dc.language.iso	en	en
dc.rights.uri	https://creativecommons.org/licenses/by-nc/3.0/	en
dc.subject.ddc	541 Physikalische Chemie	de
dc.subject.other	surfactant	en
dc.subject.other	pH	en
dc.subject.other	self-assembly	en
dc.subject.other	SANS	en
dc.subject.other	small-angle neutron scattering	en
dc.subject.other	light scattering	en
dc.title	Neutralisation rate controls the self-assembly of pH-sensitive surfactants	en
dc.type	Article	en
dc.type.version	publishedVersion	en
dcterms.bibliographicCitation.doi	10.1039/C9SM00950G	en
dcterms.bibliographicCitation.journaltitle	Soft Matter	en
dcterms.bibliographicCitation.originalpublishername	Royal Society of Chemistry	en
dcterms.bibliographicCitation.originalpublisherplace	Cambridge	en
dcterms.bibliographicCitation.pageend	8620	en
dcterms.bibliographicCitation.pagestart	8611	en
dcterms.bibliographicCitation.volume	15	en
tub.accessrights.dnb	free	en
tub.affiliation	Fak. 2 Mathematik und Naturwissenschaften::Inst. Chemie::FG Physikalische Chemie / Molekulare Materialwissenschaften	de
tub.affiliation.faculty	Fak. 2 Mathematik und Naturwissenschaften	de
tub.affiliation.group	FG Physikalische Chemie / Molekulare Materialwissenschaften	de
tub.affiliation.institute	Inst. Chemie	de
tub.publisher.universityorinstitution	Technische Universität Berlin	en