TY - JOUR
T1 - Glass transition behavior of hyper-branched polystyrenes
AU - Akabori, Kei ichi
AU - Atarashi, Hironori
AU - Ozawa, Masaaki
AU - Kondo, Tetsuo
AU - Nagamura, Toshihiko
AU - Tanaka, Keiji
N1 - Funding Information:
We would like to express our deep appreciation of fruitful discussions with Prof. K. Fukao (Ritsumeikan Univ.), Prof. K. Saito (Univ. of Tsukuba), Prof. A. Takahara, Dr. M. Kobayashi, Ms. Y. Mizutani (Kyushu Univ.), and Dr. M. Miyamoto, Mr. K. Odoi, Mr. A. Tanaka, Dr. K. Yasui, and Dr. O. Hirata (Nissan Chemical Ind. Ltd.). This research was partly supported by the Grant-in-Aids for Young Scientists A (No. 21685013), for Science Research in a Priority Area “Soft Matter Physics” (No. 21015022) and for the Global COE Program, “Science for Future Molecular Systems” from the Ministry of Education, Culture, Sports, Science and Technology, Japan. This research was also supported in part by the Industrial Technology Research Grant Program in 2006 from the New Energy and Industrial Technology Development Organization (NEDO) of Japan.
PY - 2009/9/23
Y1 - 2009/9/23
N2 - Hyper-branched polystyrenes (HBPS) were synthesized. The bulk glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) for two kinds of HBPS with an equivalent Mw, which were fractionated from different lots, were different, being respectively higher and lower than that of the corresponding linear polystyrene (PS). Infrared spectroscopy revealed that the Tg of HBPS increased with an increasing extent of intramolecular cross-linking, or cyclization, in the molecule. The segmental dynamics of HBPS was examined by dynamic mechanical analysis. The relaxation temperature for the segmental motion in HBPS was consistent with the DSC results. The fragility index was always lower for HBPS than for the linear PS, regardless of its primary structure and chain end chemistry. This would indicate that the segmental motion for HBPS is less cooperative than that of the linear PS, probably due to a lack of intermolecular chain entanglements in HBPS.
AB - Hyper-branched polystyrenes (HBPS) were synthesized. The bulk glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) for two kinds of HBPS with an equivalent Mw, which were fractionated from different lots, were different, being respectively higher and lower than that of the corresponding linear polystyrene (PS). Infrared spectroscopy revealed that the Tg of HBPS increased with an increasing extent of intramolecular cross-linking, or cyclization, in the molecule. The segmental dynamics of HBPS was examined by dynamic mechanical analysis. The relaxation temperature for the segmental motion in HBPS was consistent with the DSC results. The fragility index was always lower for HBPS than for the linear PS, regardless of its primary structure and chain end chemistry. This would indicate that the segmental motion for HBPS is less cooperative than that of the linear PS, probably due to a lack of intermolecular chain entanglements in HBPS.
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U2 - 10.1016/j.polymer.2009.08.029
DO - 10.1016/j.polymer.2009.08.029
M3 - Article
AN - SCOPUS:69849086865
SN - 0032-3861
VL - 50
SP - 4868
EP - 4875
JO - Polymer
JF - Polymer
IS - 20
ER -