18 آذر 1400

حسین اسلامی

مرتبه علمی: استاد
نشانی: دانشکده علوم و فناوری نانو و زیستی - گروه شیمی
تحصیلات: دکترای تخصصی / شیمی
تلفن: 09100000000
دانشکده: دانشکده علوم و فناوری نانو و زیستی

مشخصات پژوهش

عنوان Structure and dynamics of stereo-regular poly(methyl-methacrylate) melts through atomistic molecular dynamics simulations
نوع پژوهش مقالات در نشریات
کلیدواژه‌ها
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مجله Soft Matter
شناسه DOI
پژوهشگران Alireza Behbahani (نفر اول) ، مهدی واعظ (نفر دوم) ، قدرت اله مطلق (نفر سوم) ، حسین اسلامی (نفر چهارم) ، Vegalis Harmandaris (نفر پنجم)

چکیده

Poly(methyl-methacrylate), PMMA, is a disubstituted vinyl polymer whose properties depend significantly on its tacticity. Here we present a detailed study of the structure, conformation, and dynamics of syndiotactic, atactic, and isotactic PMMA melts at various temperatures (580, 550, 520, and 490 K) via all-atom molecular dynamics simulations. The calculated volumetric properties are close to experimental data. The Tg and chain dimensions of PMMA model systems are found to depend strongly on tacticity in agreement with experimental findings. The backbone bonds in trans (t), diads in tt, and inter-diads in t|t torsional states are the most populated for all PMMA stereo-chemistries and their fractions increase with the number of syndiotactic sequences. Also, the effective torsional barrier heights for the backbone, ester side group, and a-methyl group are larger for syndiotactic PMMA compared to the isotactic one. The structure of the PMMA chains is studied by computing the intraand inter-chain static structure factors, S(q), and the radial pair distribution functions. In the first peak of S(q), both intra- and inter-chain components contribute, whereas the second and third peaks mainly come from inter- and intra-chain parts, respectively. For all PMMA stereo-isomers a clear tendency of ester-methyl groups to aggregate is observed. The local dynamics are studied by analyzing torsional autocorrelation functions for various dihedral angles.