Correlation between fragility and cooperativity in segmental dynamics of glass-forming para-substituted polystyrenes

• 資料種別: 文書・図像類
• タイトル: Correlation between fragility and cooperativity in segmental dynamics of glass-forming para-substituted polystyrenes
• 著者・編者: Sasaki, Takashi; Ichimura, Mizuki; Irie, Satoshi
• 著者標目: Sasaki, Takashi; Ichimura, Mizuki; Irie, Satoshi
• 出版事項: Nature Publishing Group
• 出版年月日等: 2015-10
• 出版年（W3CDTF）: 2015-10
• タイトル（掲載誌）: Polymer Journal
• 巻号年月日等（掲載誌）: 47 10
• 掲載巻: 47
• 掲載号: 10
• 掲載ページ: 687-694
• 本文の言語コード: eng
• 件名標目: cooperativity; fragility; glass transition; polystyrene derivatives
• 対象利用者: 一般
• 一般注記: 出版タイプ： AO; To understand the mechanism of the viscous slowdown in supercooled liquids that is responsible for glass transition, we investigate the interrelation between glass transition temperature Tg, fragility, and cooperativity in segmental dynamics. Polymeric glass-formers having a similar chemical structure are expected to exhibit clear correlations between the above parameters. In this paper, polystyrene (PS) derivatives possessing various para-substituents are studied using calorimetry in regard to the fragility parameter m, dynamic length scale ξ, and the number of cooperatively rearranging segments NCRR at Tg. Positive correlations were revealed for both NCRR(Tg) vs. m and ξ3(Tg) vs. m. Both fragility and cooperativity were found to increase as the bulkiness of the substituent increases. Wide-angle X-ray scattering measurements revealed that the structural correlation between backbone chains is reduced as the bulkiness increases. This may be responsible for the reduced cooperativity. In contrast, for poly(methacrylic acid ester)s, the relations between the above parameters appeared to be less clear. The clear trend observed for the PS system may be due to the rigidity of the phenylene unit, through which the substituent directly affects the backbone dynamics. The estimated activation energy per segment increased consistently with an increase in the para-substituent's bulkiness.
• 著作権情報: 〓 2015 The Society of Polymer Science, Japan
• 連携機関・データベース: 国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）; https://irdb.nii.ac.jp
• 提供元機関・データベース: 福井大学 : 福井大学学術機関リポジトリ