پیوندزنی زنجیرهای پلی‌استیرن به لبه نانولایه‌های گرافن به روش پیوندزنی از میان با استفاده از پلیمرشدن انتقال زنجیر افزایشی- جدایشی بازگشت‌پذیر

نوع مقاله: پژوهشی

نویسنده

تبریز، دانشگاه صنعتی سهند تبریز دانشکده مهندسی پلیمر، صندوق پستی 1996-51335

چکیده

نانولایه‌های گرافن با لبه عامل‌دارشده با زنجیرهای پلی‌استیرن به روش، پیوندزنی از میان و پلیمرشدن افزایشی-جدایشی برگشت‌پذیر (RAFT) تهیه شد. بدین منظور، ابتدا عامل اصلاح‌کننده با پیوند دوگانه (MD) تهیه شد. پس از اصلاح لبه گرافن اکسید (GO) با دو مقدار متفاوت از MD و تهیه گرافن‌های اصلاح‌شده با مقدار کم MD (LFG) و زیاد MD  (HFG)، پلیمرشدن RAFT درجا برای پیوندزنی زنجیرهای پلی‌استیرن به لبه نانوصفحه‌ها با دو چگالی پیوند متفاوت به‌کار گرفته شد. آزمون طیف‌سنجی زیرقرمز نشان داد، اصلاح‌کننده MD و زنجیرهای پلی‌استیرن بر لبه نانولایه‌ها پیوند خورده‌اند. رنگ‌نگاری گازی نشان داد، درصد تبدیل با افزایش مقدار گرافن اصلاح‌شده و نیز مقدار چگالی پیوند (CD) کاهش می‌یابد. متوسط عددی وزن مولکولی و شاخص پراکندگی با استفاده از روش رنگ‌نگاری ژل تراوایی بررسی شد. با افزایش مقدار گرافن اصلاح‌شده، وزن مولکولی زنجیرهای اتصال‌یافته کاهش و شاخص چندتوزیعی (PDI) آن‌ها افزایش یافت. با افزایش چگالی پیوند، وزن مولکولی کاهش یافته و PDI تغییر چندانی نمی‌کند. آزمون گرماوزن‌سنجی نشان داد، مقدار باقی‌مانده در دمای 600C برای LFG و HFG به ترتیب برابر با 45/1 و %46/8 بود. با افزایش چگالی پیوندی، مقدار تخریب مربوط به پلی‌استیرن افزایش و با افزایش مقدار گرافن کاهش یافت. نتایج پراش پرتو X برای بررسی فاصله بین صفحه‌های گرافن در اثر اصلاح به‌کار گرفته شد. تصاویر میکروسکوپی الکترونی پویشی و عبوری نشان داد، وضوح صفحه‌های گرافن با اکسایش و پوشش با زنجیر پلی‌استیرن از بین رفته است.

کلیدواژه‌ها


عنوان مقاله [English]

Grafting of Polystyrene Chains at the Edge of Graphene Nanolayers by "Grafting Through" Approach Using Reversible Addition-Fragmentation Chain Transfer Polymerization

نویسنده [English]

  • Hossein Roghani-Mamaqani
Department of Polymer Engineering, Sahand University of Technology, P.O. Box: 51335-1996, Tabriz, Iran.
چکیده [English]

Edge-functionalized graphene nanolayers with polystyrene chains were prepared by a “grafting through” reversible addition-fragmentation chain transfer (RAFT) polymerization. For this purpose, double-bond containing modifier (MD) was prepared. After edge-functionalization of graphene oxide (GO) by two different amounts of MD and preparation of modified graphenes (LFG and HFG), RAFT polymerization of styrene was applied for preparation of functionalized GO with different densities of polystyrene chains. Fourier transform infrared spectroscopy showed that MD and polystyrene chains were grafted at the edge of GO. Gas chromatography showed that conversion decreased by the addition of modified GO content and also grafting density of MD. Number-average molecular weight and polydispersity index of polystyrene chains were derived from gel permeation chromatography. Increase of modified graphene content results in a decrease in molecular weight of attached polystyrene chains and also an increase in their PDI value. Increase of grafting density of MD results in decrease of molecular weight of polystyrene chains with no considerable variation in PDI value. Thermogravimetric analysis results showed that char residue is about 45.1 and 46.8% for LFG and HFG, respectively. The content of degradation ascribed to polystyrene increased with increase of grafting density of MD and decreased with increase of modified graphene content. X-ray diffraction results were used for evaluation of interlayer spacing of graphene layers after functionalization process and also study of nanocomposites structure. The results of scanning electron microscopy and transmission electron microscopy show that graphene layers with high clarity turned to opaque layers with lots of creases by oxidation and attachment of polystyrene chains.

کلیدواژه‌ها [English]

  • Polystyrene
  • graphene nanolayers
  • grafting through
  • reversible addition-fragmentation chain transfer polymerization (RAFT)
  • grafting density

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