Impact of the Pendant Group on the Chain Conformation and Bulk Properties of Norbornene Imide-Based Polymers
Impact of the Pendant Group on the Chain Conformation and Bulk Properties of Norbornene Imide-Based Polymers
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DOI：
10.1021/acs.macromol.9b00020
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发表时间：
2019-05-14
期刊：
影响因子：
5.5
通讯作者：
Ding, Yifu
中科院分区：
文献类型：
--
作者：
Boyle, Bret M.;Heinz, Ozge;Ding, Yifu
合成了三个系列的具有不同侧基的基于双烯酰亚胺的聚合物，以研究侧基对聚合物在溶液中的构象和本体熔体性质的影响。这三个系列中的每一个都通过静态光散射分析聚合物的本体z-平均回转半径和通过振荡测量和差示扫描量热法分析聚合物的熔体粘弹性来检查。空间体积庞大的侧楔基团适度地增加了聚亚苯基酰亚胺聚合物的棒状构象，然而，聚合物主链的固有刚性仍然可以用体积较小的取代基观察到。与此形成鲜明对比的是，不同的侧基显著影响本体粘弹性和热性能。通过增加侧基尺寸，聚合物的链直径增加并降低缠结模量。最后，随着楔形侧基尺寸的增加，这些基于聚烯烃的聚合物的链段松弛时间和脆性指数降低。
Three series of well-defined norbornene imide-based polymers with different pendant groups were synthesized to investigate the effect of the pendant group on the polymer conformation in solution and bulk melt properties. Each of these three series was examined by analyzing the polymers' bulk z-average radius of gyration via static light scattering and the polymers' melt viscoelastic properties via oscillatory measurements and differential scanning calorimetry. Sterically bulky pendant wedge groups modestly increase the rodlike conformation of the norborneneimide polymer, however, the inherent rigidity of the polymer main-chain can still be observed with less bulky substituents. In stark contrast, the different side groups significantly impacted the bulk viscoelastic and thermal properties. By increasing the pendant group size, the chain diameter of the polymer increases and lowers the entanglement modulus. Finally, as the wedge pendant group size increases, the segmental relaxation time and the fragility index of these norbornene-based polymers are decreased.