From coffee stains to uniform deposits: Significance of the contact-line mobility.
J Colloid Interface Sci
; 608(Pt 2): 1718-1727, 2022 Feb 15.
Article
em En
| MEDLINE
| ID: mdl-34742086
HYPOTHESIS: Contact-line motion upon drying of a sessile droplet strongly affects the solute transport and solvent evaporation profile. Hence, it should have a strong impact on the deposit formation and might be responsible for volcano-like, dome-like and flat deposit morphologies. EXPERIMENTS: A method based on a thin-film interference was used to track the drop height profile and contact line motion during the drying. A diverse set of drying scenarios was obtained by using inks with different solvent compositions and by adjusting the substrate wetting properties. The experimental data was compared to the predictions of a phenomenological model. FINDINGS: We highlight the essential role of contact-line mobility on the deposit morphology of solution-based inks. A pinned contact line produces exclusively ring-like deposits under normal conditions. On the contrary, drops with a mobile contact line can produce ring-, flat- or dome-like morphology. The developed phenomenological model shows that the deposit morphology depends on solvent evaporation profile, evolution of the drop radius relative to its contact angle, and the ratio between initial and maximal (gelling) solute concentration. These parameters can be adjusted by the ink solvent composition and substrate wetting behaviour, which provides a way for deposition of uniform and flat deposits via inkjet printing.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Café
/
Corantes
Tipo de estudo:
Prognostic_studies
/
Qualitative_research
Idioma:
En
Revista:
J Colloid Interface Sci
Ano de publicação:
2022
Tipo de documento:
Article
País de publicação:
Estados Unidos