Flattening Process of Polymer Chains Irreversibly Adsorbed on a Solid

Mani Sen, Naisheng Jiang, Justin Cheung, Maya K. Endoh, Tadanori Koga, Daisuke Kawaguchi, Keiji Tanaka

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

We report the structural relaxation process of irreversibly adsorbed polymer chains via thermal annealing that lie flat on a solid ("flattened chains"). Amorphous polystyrene and quartz, which together constitute a weakly attractive system, was used as a model where the local chain conformations of the flattened chains were investigated by sum frequency generation spectroscopy (SFG). Two different film preparation processes (i.e., spin coating and dip coating methods) were utilized to create different initial chain conformations. The spin-coated and dip-coated PS thin films were annealed at a temperature far above the bulk glass transition temperature to reach the "quasiequilibrium" state and subsequently rinsed with chloroform to uncover the buried flattened chains. The SFG results revealed that the backbone chains (constituted of CH and CH2 groups) of the flattened PS chains preferentially orient to the weakly interactive substrate surface via thermal annealing regardless of the initial chain conformations, while the orientation of the phenyl rings becomes randomized. We postulate that increasing the number of surface-segmental contacts (i.e., enthalpic gain) is the driving force for the flattening process of the polymer chains, even onto a weakly interactive solid to overcome the conformational entropy loss in the total free energy.

Original languageEnglish
Pages (from-to)504-508
Number of pages5
JournalACS Macro Letters
Volume5
Issue number4
DOIs
Publication statusPublished - Apr 19 2016

All Science Journal Classification (ASJC) codes

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

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