Modulation of electroactive polymer film dynamics by metal ion complexation and redox switching

• Tipo: Artigo em Revista Científica Internacional
• Data: 2009

Autores

Joao Tedim (Autor) Outra; Cristina Freire (Autor) FCUP; Robert R Hillman (Autor) Outra

Revista

Título: Soft Matter

Vol. 5

Páginas: 2603-2613

ISSN: 1744-683X

Editora: Royal Society of Chemistry

Indexação

ISI Web of Knowledge - 5 Citações

Scopus - 5 Citações

Classificação Científica

FOS: Ciências da engenharia e tecnologias > Engenharia dos materiais

Outras Informações

ID Authenticus: P-003-S7W

DOI: 10.1039/b903509e

Abstract (EN): The viscoelastic properties of [Ni(salen)(crown ether)] conducting polymer films were characterized using high frequency acoustic wave resonators. Shear moduli values respond to film redox state and barium ion complexation. The variations in storage and loss moduli are significant, but always such that the films are viscoelastic, i.e. a soft material. Both components are increased by polymer oxidation, the loss modulus to a greater extent. In the absence of Ba(2+), the similarity of shear moduli-and nanogravimetric-potential signatures (for acoustically thick and thin films, respectively) provides a compositional explanation for changes in film dynamics. Ba(2+) uptake restricts the extent of film redox switching. In the presence of Ba(2+) the pattern of redox driven shear modulus changes is unaltered, but the values of both components are systematically higher. These changes are interpreted in terms of (i) space limited accommodation of counter ions (ii) crown-Ba(2+)-crown crosslinking between polymer chains, and (iii) decreased free volume for plasticizing solvent. We suggest that the first of these is the origin of the restricted charge injection (controlled by electroneutrality), the second of the increased storage moduli, and the third of the increased loss moduli. Observations at different time scales, via acoustic wave resonator harmonics, reveal increases in both shear moduli components with increasing frequency; these are considered in the light of simple mechanical models for polymer dynamics.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 11