Please use this identifier to cite or link to this item: http://hdl.handle.net/10316/95676
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dc.contributor.authorGonçalves, Rui A.-
dc.contributor.authorLam, Yeng-Ming-
dc.contributor.authorLindman, Björn-
dc.date.accessioned2021-08-25T15:42:41Z-
dc.date.available2021-08-25T15:42:41Z-
dc.date.issued2021-06-28-
dc.identifier.issn1420-3049pt
dc.identifier.urihttp://hdl.handle.net/10316/95676-
dc.description.abstractDouble-chain amphiphilic compounds, including surfactants and lipids, have broad significance in applications like personal care and biology. A study on the phase structures and their transitions focusing on dioctadecyldimethylammonium chloride (DODAC), used inter alia in hair conditioners, is presented. The phase behaviour is dominated by two bilayer lamellar phases, Lβ and Lα, with "solid" and "melted" alkyl chains, respectively. In particular, the study is focused on the effect of additives of different polarity on the phase transitions and structures. The main techniques used for investigation were differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SAXS and WAXS). From the WAXS reflections, the distance between the alkyl chains in the bilayers was obtained, and from SAXS, the thicknesses of the surfactant and water layers. The Lα phase was found to have a bilayer structure, generally found for most surfactants; a Lβ phase made up of bilayers with considerable chain tilting and interdigitation was also identified. Depending mainly on the polarity of the additives, their effects on the phase stabilities and structure vary. Compounds like urea have no significant effect, while fatty acids and fatty alcohols have significant effects, but which are quite different depending on the nonpolar part. In most cases, Lβ and Lα phases exist over wide composition ranges; certain additives induce transitions to other phases, which include cubic, reversed hexagonal liquid crystals and bicontinuous liquid phases. For a system containing additives, which induce a significant lowering of the Lβ-Lα transition, we identified the possibility of a triggered phase transition via dilution with water.pt
dc.description.sponsorshipThis research was funded by Procter & Gamble and Agency for Science, Technology and Research (A*STAR), Singapore (APG2013/016), Singapore Ministry of Education Academic Research Fund Tier 1 (2019-T1-002-35) and FCT.pt
dc.language.isoengpt
dc.publisherMDPIpt
dc.relationUID/QUI/00313/2020pt
dc.rightsopenAccesspt
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/pt
dc.subjectAdditive effectspt
dc.subjectDouble-chain surfactantpt
dc.subjectHair conditionerpt
dc.subjectLamellar gelpt
dc.subjectLamellar liquid crystapt
dc.subjectSurfactant packingpt
dc.titleDouble-Chain Cationic Surfactants: Swelling, Structure, Phase Transitions and Additive Effectspt
dc.typearticle-
degois.publication.firstPage3946pt
degois.publication.issue13pt
degois.publication.titleMoleculespt
dc.peerreviewedyespt
dc.identifier.doi10.3390/molecules26133946pt
degois.publication.volume26pt
dc.date.embargo2021-06-28*
uc.date.periodoEmbargo0pt
item.fulltextCom Texto completo-
item.languageiso639-1en-
item.grantfulltextopen-
crisitem.author.deptFaculty of Sciences and Technology-
crisitem.author.parentdeptUniversity of Coimbra-
crisitem.author.researchunitCQC - Coimbra Chemistry Centre-
crisitem.author.parentresearchunitFaculty of Sciences and Technology-
crisitem.author.orcid0000-0002-7493-9112-
Appears in Collections:I&D CQC - Artigos em Revistas Internacionais
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This item is licensed under a Creative Commons License Creative Commons