Rubbing-induced molecular alignment and its relaxation in polystyrene thin films
文献类型：期刊论文
| 作者 | Tsang, OC; Xie, FC; Tsui, OKC; Yang, Z; Zhang, JM; Shen, DY; Yang, XZ |
| 刊名 | JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
 |
| 出版日期 | 2001-11-15 |
| 卷号 | 39期号:22页码:2906-2914 |
| 关键词 | Polymer Thin Films Dynamic Properties Optical Anisotropy Oriented Polymers Glass Transitions Rubbing Ftir |
| ISSN号 | 0887-6266 |
| 英文摘要 | Rubbing-induced molecular alignment and its relaxation in polystyrene (PS) thin films are studied with optical birefringence. A novel relaxation of the alignment is observed that is distinctly different from the known relaxation processes of PS. First, it is not the Kohlrausch-Williams-Watts type but instead is characterized by two single exponentials plus a temperature-dependent constant. At temperatures several degrees or more below the glass-transition temperature (T-g), the relaxation time falls between that of the a and beta relaxations. Second, the decay time constants are the same within 40% for PS with weight-average molecular weights (M-w's) of 13,700-550,000 Da at temperatures well below the sample T-g 's, indicating that the molecular relaxations involved are mostly local within the entanglement distance. Nonetheless, the temperature at which the rubbing-induced molecular alignment disappears (TO) exhibits a strong M-w dependence and closely approximates the T-g of the sample. Furthermore, To depends notably on the thickness of the polymer in much the same way as previously found for the T-g of supported PS films. This suggests that the a process becomes dominant near T-g. Preliminary spectroscopic studies in the mid-infrared range show a significant degree of bending of the phenyl ring toward the sample surface, with the C-C bond connecting the phenyl ring and the main chain tends to lie along the rubbing direction, which indicates that the relaxation is connected with the reorientation of this C-C bond. We exclude the observed relaxation, as predominantly a near-surface one, because detailed studies on the effects of rubbing conditions on the degree of molecular alignment indicate that the alignment is not local to the polymer-air surface. (C) 2001 John Wiley & Sons, Inc. |
| 语种 | 英语 |
| WOS记录号 | WOS:000171853200018 |
| 出版者 | JOHN WILEY & SONS INC |
| 源URL | [http://ir.iccas.ac.cn/handle/121111/77391]  |
| 专题 | 中国科学院化学研究所 |
| 通讯作者 | Tsui, OKC |
| 作者单位 | 1.Hong Kong Univ Sci & Technol, Dept Phys, Kowloon, Hong Kong, Peoples R China 2.Chinese Acad Sci, Inst Chem, Beijing 100080, Peoples R China |
| 推荐引用方式 GB/T 7714 | Tsang, OC,Xie, FC,Tsui, OKC,et al. Rubbing-induced molecular alignment and its relaxation in polystyrene thin films[J]. JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS,2001,39(22):2906-2914. |
| APA | Tsang, OC.,Xie, FC.,Tsui, OKC.,Yang, Z.,Zhang, JM.,...&Yang, XZ.(2001).Rubbing-induced molecular alignment and its relaxation in polystyrene thin films.JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS,39(22),2906-2914. |
| MLA | Tsang, OC,et al."Rubbing-induced molecular alignment and its relaxation in polystyrene thin films".JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 39.22(2001):2906-2914. |
入库方式： OAI收割
来源：化学研究所
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