Unusual Phase Behavior of a Mesogen-Jacketed Liquid Crystalline Polymer Synthesized by Atom Transfer Radical Polymerization
Unusual Phase Behavior of a Mesogen-Jacketed Liquid Crystalline Polymer Synthesized by Atom Transfer Radical Polymerization
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DOI：
10.1021/ma0514370
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发表时间：
2006-01
期刊：
影响因子：
5.5
通讯作者：
Yongfeng Zhao;Xinghe Fan;X. Wan;Xiaofang Chen;Yi;Liangyuan Wang;Xia Dong;Qifeng Zhou
中科院分区：
文献类型：
--
作者：
Yongfeng Zhao;Xinghe Fan;X. Wan;Xiaofang Chen;Yi;Liangyuan Wang;Xia Dong;Qifeng Zhou
采用原子转移自由基聚合法合成了一系列分子量范围宽（Mn = 1.24 × 104 - 35.6 × 104）、分子量分布窄（Mw/Mn ≤ 1.18）的夹套液晶聚合物聚{2，5-双[（4-丁氧基苯基）氧羰基]苯乙烯}（PBPCS）。所得的聚合物已被研究的技术，包括差示扫描量热法，偏光显微镜，和X-射线散射的组合。Mn ≤ 2.42 × 104的样品为各向同性。Mn ≥ 3.36 × 104的样品在较低温度下表现出稳定的各向同性相，在较高温度下表现出液晶相。相行为表现出非常类似于可重入各向同性相的现象。这些转变与作为温度函数测量的流变学性质相关。研究了聚合物在各向同性相和液晶相中的流变行为。在这些实验的基础上，
A series of mesogen-jacketed liquid crystalline polymers, poly{2,5-bis[(4-butoxyphenyl)oxycarbonyl]styrenes} (PBPCS), with a wide range of molecular weights (Mn = 1.24 × 104−35.6 × 104) and narrow molecular weight distributions (Mw/Mn ≤ 1.18) have been synthesized by atom transfer radical polymerization. The resulting polymers have been investigated by a combination of techniques including differential scanning calorimetry, polarized optical microscopy, and X-ray scattering. The samples with Mn ≤ 2.42 × 104 are isotropic. The samples with Mn ≥ 3.36 × 104 display a thermodynamically stable isotropic phase at lower temperature and a liquid crystalline (LC) phase at higher temperature. The phase behavior shows a phenomenon quite similar to the reentrant isotropic phase. These transitions are correlated with the rheological properties measured as a function of temperature. The rheological behavior of the polymer in the isotropic phase and in the LC phase has been studied as well. On the basis of these experim...