Thermal Stability and Ordering Study of Long- and Short-Alkyl Chain Phosphonic Acid Multilayers

Author(s)

de Pauli, Muriel ^{[1, 2]} ; Prado, Mariana de Castro ^[3] ; Souza Matos, Matheus Josue ^[3] ; Fontes, Giselle Nogueira ^[4] ; Perez, Carlos Alberto ^[2] ; Carvalho Mazzoni, Mario Sergio ^[3] ; Almeida Neves, Bernardo Ruegger ^[3] ; Malachias, Angelo ^[3]

Affiliation

^[1] Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13083859 Campinas, SP - Brazil

^[2] Lab Nacl Luz Sincrotron, BR-13083970 Campinas, SP - Brazil

^[3] Univ Fed Minas Gerais, Depto Fis, ICEx, BR-30123970 Belo Horizonte, MG - Brazil

^[4] Inst Nacl Metrol Normalizacao & Qualidade Ind INM, Div Mat Metrol, BR-25250020 Duque De Caxias, RJ - Brazil

• Document type: Journal article
• Source: Langmuir; v. 28, n. 43, p. 15124-15133, OCT 30 2012.
• Web of Science Citations: 7

Abstract

Long-range order evolution of self-assembled phosphonic acid multilayers as a function of temperature is studied here for two molecules with different alkyl chain length. By using synchrotron conventional diffraction, distinct order configurations are retrieved on phosphonic acid multilayers and their thermodynamic behavior monitored by energy-dispersive diffraction. This later technique allows us to observe the system behavior near order-disorder temperatures, as well as to determine the most stable configurations in the range from room temperature up to 120 degrees C. Planar order is also addressed by wide-angle X-ray scattering (WAXS) transmission experiments. Order parameter phase diagrams are built based on the experimental results, showing the dominant configuration at each temperature. The multilayer molecular long-range order retrieved from the experiments is corroborated by first principles calculations based on the Density Functional Theory. The bulk configurations depicted in this work are produced by molecule-molecule interactions and allow for future comparisons with the behavior of ordered molecules in few-monolayers configurations, commonly used in organic devices, where the presence of surfaces and interfaces strongly affects the molecule packing. (AU)

• FAPESP's process: 09/11875-2 - Energy dispersive diffraction study of long range ordering and thermodynamic properties of phosphonic acid multilayers
• Grantee: Muriel de Pauli
• Support Opportunities: Scholarships in Brazil - Master