Utilize este identificador para referenciar este registo: https://hdl.handle.net/10316/95676
Título: Double-Chain Cationic Surfactants: Swelling, Structure, Phase Transitions and Additive Effects
Autor: Gonçalves, Rui A.
Lam, Yeng-Ming
Lindman, Björn 
Palavras-chave: Additive effects; Double-chain surfactant; Hair conditioner; Lamellar gel; Lamellar liquid crysta; Surfactant packing
Data: 28-Jun-2021
Editora: MDPI
Projeto: UID/QUI/00313/2020 
Título da revista, periódico, livro ou evento: Molecules
Volume: 26
Número: 13
Resumo: Double-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.
URI: https://hdl.handle.net/10316/95676
ISSN: 1420-3049
DOI: 10.3390/molecules26133946
Direitos: openAccess
Aparece nas coleções:I&D CQC - Artigos em Revistas Internacionais

Ficheiros deste registo:
Ficheiro Descrição TamanhoFormato
molecules-26-03946-v2.pdf9.88 MBAdobe PDFVer/Abrir
Mostrar registo em formato completo

Citações SCOPUSTM   

5
Visto em 15/abr/2024

Citações WEB OF SCIENCETM

5
Visto em 2/abr/2024

Visualizações de página

144
Visto em 16/abr/2024

Downloads

92
Visto em 16/abr/2024

Google ScholarTM

Verificar

Altmetric

Altmetric


Este registo está protegido por Licença Creative Commons Creative Commons