Terpolymerization of propylene oxide and vinyl oxides with CO2: copolymer cross-linking and surface modification via thiol-ene click chemistry
Terpolymerization of propylene oxide and vinyl oxides with CO2: copolymer cross-linking and surface modification via thiol-ene click chemistry
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DOI：
10.1039/c4py01612b
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发表时间：
2015-01-01
影响因子：
4.6
通讯作者：
Wang, Yanyan
中科院分区：
文献类型：
--
作者：
Darensbourg, Donald J.;Wang, Yanyan
由二元和双官能（salen）Co（III）配合物催化的带有乙烯基的环氧化物、环氧丙烷和二氧化碳的三聚反应已经提供了取决于环氧化物单体的进料比的各种组成的聚碳酸酯。 Fineman-Ross 对这些聚合反应的分析表明，25℃ 下环氧丙烷 (PO)/乙烯基氧化物 (VIO)/CO2 的反应活性比为 r(PO) = 3.74 和 r(VIO) = 0.224，这反映了环氧化物与钴中心的结合常数以及开环过程的速率常数。当使用 PO/烯丙基缩水甘油醚 (AGE)/CO2 进行该过程时，发现环氧化物的差别较小，其中 25 ℃ 下的反应性参数为 r(PO) = 0.755 和 r(AGE) = 0.876。为了增强聚碳酸酯的机械和热性能，PO/AGE/CO2 的三元共聚物的乙烯基侧基更加随机 分布在聚合物材料中，使用两种不同的硫醇，乙二醇双（3-巯基丙酸酯）和季戊四醇四（巯基乙酸酯）通过硫醇-烯化学进行交联。 FT-拉曼光谱提供了成功交联发生的证据。对这些三元共聚物进行动态机械分析（DMA）测量，作为交联密度的函数。由四齿交联剂衍生的交联膜在 50% 至 100% C=C 键转化率之间表现出橡胶模量增加 50%；与此同时，T-g 随着交联密度的增加而增加。此外，将具有25％C=C键转化率的交联膜与N-乙酰基-L-半胱氨酸和2-(Boc-氨基)乙硫醇反应，并通过FTIR和XPS证实，可提供用于各种应用的含有羧基或胺基团的表面功能化膜。
Terpolymerization reactions of epoxides bearing vinyl groups, propylene oxide and carbon dioxide catalyzed by binary and bifunctional (salen) Co(III) complexes have provided polycarbonates of various compositions depending on the feed ratios of the epoxide monomers. Fineman-Ross analysis of these polymerization reactions revealed reactivity ratios for propylene oxide (PO)/vinyl oxide (VIO)/CO2 of r(PO) = 3.74 and r(VIO) = 0.224 at 25 degrees C which reflect both the binding constants of the epoxides to the cobalt center as well as the rate constants for the ring-opening process. Less discrimination of epoxides was noted when carrying out the process using PO/allyl glycidyl ether (AGE)/CO2, where the reactivity parameters were r(PO) = 0.755 and r(AGE) = 0.876 at 25 degrees C. In order to enhance the polycarbonate's mechanical and thermal properties the terpolymers from PO/AGE/CO2, where the vinyl pendant groups are more randomly distributed in the polymeric material, were cross-linked via thiol-ene chemistry using two different thiols, ethylene glycol bis(3-mercaptoproionate) and pentaerythritol tetrakis(mercaptoacetate). FT-Raman spectroscopy provided evidence that successful cross-linking has occurred. Dynamic mechanical analysis (DMA) measurements on these terpolymers were performed as a function of the cross-link densities. Cross-linked films derived from the tetradentate cross-linker displayed a 50% increase in rubbery modulus between 50% and 100% C=C bond conversion; concomitantly, the T-g increased with increasing cross-link densities. In addition, the cross-linked films with 25% C=C bond conversion were reacted with N-acetyl-L-cysteine and 2-(Boc-amino) ethanethiol, and confirmed by FTIR and XPS, to provide surface functionalized films containing carboxyl or amine groups for various applications.