Interfacial and annealing effects on primary α-relaxation of ultrathin polymer films investigated at nanoscale

Hung K. Nguyen, Massimiliano Labardi, Simone Capaccioli, Mauro Lucchesi, Pierangelo Rolla, Daniele Prevosto

    Research output: Contribution to journalArticlepeer-review

    37 Citations (Scopus)

    Abstract

    The influence of interfacial interactions and annealing time on dynamics of the α-relaxation in ultrathin poly(vinyl acetate) films deposited on different substrates has been studied using local dielectric spectroscopy at ambient pressure and controlled humidity. After annealing at 323 K for about 3 days, for polymer films supported on gold and aluminum substrates, an increase of the relaxation rate with decreasing film thickness below 30-35 nm was observed, whereas for films deposited on silicon substrates a thickness-independent dynamics was found for films as thin as 12 nm. The difference in size effect on dynamics of the films could reasonably be related to the difference in interfacial energy between polymer films and substrates, even though a criterion simply based on interfacial energy cannot be used to explain all the results. In fact, further annealing at a higher temperature evidenced an annealing-dependent dynamics in films prepared on aluminum substrates consistent with the presence of long-living metastable states at the polymer/substrate interface. The lifetime of such metastable states seems related to the nature of the substrate as well as to the molecular weight of the polymer.

    Original languageEnglish
    Pages (from-to)2138-2144
    Number of pages7
    JournalMacromolecules
    Volume45
    Issue number4
    DOIs
    Publication statusPublished - 2012 Feb 28

    ASJC Scopus subject areas

    • Organic Chemistry
    • Polymers and Plastics
    • Inorganic Chemistry
    • Materials Chemistry

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