Orientation and Birefringence Compensation of Trunk and Graft Chains in Drawn Films of Cellulose Acetate-graft-PMMA Synthesized by ATRP
Orientation and Birefringence Compensation of Trunk and Graft Chains in Drawn Films of Cellulose Acetate-graft-PMMA Synthesized by ATRP
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DOI：
10.1021/ma400155f
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发表时间：
2013-04
期刊：
影响因子：
5.5
通讯作者：
H. Yamanaka;Yoshikuni Teramoto;Y. Nishio
中科院分区：
文献类型：
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作者：
H. Yamanaka;Yoshikuni Teramoto;Y. Nishio
我们考察了醋酸纤维素(CA)-接枝-聚甲基丙烯酸甲酯(PMMA)薄膜拉伸引起的分子取向和光学各向异性与侧链含量的关系。采用原子转移自由基聚合法合成了共聚物。在故意切割PMMA接枝前后，通过核磁共振和凝胶渗透色谱分析成功地进行了分子表征。即使接枝产物的相对分子质量增加，分散性指数也保持在1.2以下。用荧光探针技术研究了共聚物在单轴拉伸薄膜中的分子取向行为。测试表明，随着共聚物中MMA单元摩尔取代度的增加，取向发展呈下降趋势。在薄膜伸长某一阶段的双折射率(Δn)比较中，Δn值随MS的增加而迅速下降，最终导致原始CA的Δn由正向转变。
We examined the molecular orientation and optical anisotropy that are induced by the stretching of cellulose acetate (CA)-graft-poly(methyl methacrylate) (PMMA) films, in connection with the side-chain contents. The copolymers were prepared by atom transfer radical polymerization. The molecular characterization was successfully performed by NMR and GPC analyses, before and after deliberate cleavage of the PMMA grafts. Even if the molecular weight of the grafts increased, the dispersity index remained below 1.2. The molecular orientation behavior in uniaxially drawn films of the copolymers was estimated by a fluorescence probe technique. The measurement revealed a declining tendency of the orientation development with an increase in degree of the molar substitution (MS) of MMA unit of the copolymers. In comparison of birefringence (Δn) at a given stage of elongation of the films, the value of Δn decreased rapidly with increasing MS, which eventually led to the conversion from a positive Δn for pristine CA ...