کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
190167 459693 2011 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Correlation between ion-exchange properties and swelling/shrinking processes in hexasulfonated calix[6]arene doped polypyrrole films: ac-electrogravimetry and electrochemical atomic force microscopy investigations
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Correlation between ion-exchange properties and swelling/shrinking processes in hexasulfonated calix[6]arene doped polypyrrole films: ac-electrogravimetry and electrochemical atomic force microscopy investigations
چکیده انگلیسی

Electrogenerated polypyrrole films doped with hexasulfonated calix[6]arenes were subjected to ac-electrogravimetry and electrochemical atomic force microscopy (EC-AFM) studies in aqueous potassium nitrate solutions. The former technique reveals that these films are mainly cation exchangers although solvent molecules (H2O) and anions (NO3−) are also exchanged, in much lower amounts, in the course of the doping/undoping process. Unexpectedly, within the potential range encompassing this process, K+ cations were found to be exchanged for more cathodic potentials whereas H3O+ are exchanged for more anodic potentials. EC-AFM investigations revealed substantial shrinking and swelling during the oxidation (doping) and reduction (undoping) processes respectively. An obvious correlation can easily be built between these observations: the oxidation of the polymer films provokes an expulsion of the cations, as expected from cation exchanger polymer films, and therefore a decrease of the volume (and thickness) of these films whereas their reduction causes an insertion of cations and an increase of their volume (and thickness). This electromechanical mechanism is amplified by the simultaneous exchange of free water molecules. Suggestions based on these observations, on structural characteristics of polypyrrole films, and on complexation ability of hexasulfonated calix[6]arenes incorporated in the films are discussed to explain (i) the change of the identity of the exchanged cations as a function of the potential, (ii) the exchange of free water molecules and, (iii) the exchange of small amounts of nitrate ions.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Electrochimica Acta - Volume 56, Issue 10, 1 April 2011, Pages 3516–3525
نویسندگان
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