Polar Additive Triggered Branching Switch and Block Polyolefin Topology in Living Ethylene Polymerization,Macromolecules

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Polar Additive Triggered Branching Switch and Block Polyolefin Topology in Living Ethylene Polymerization
Macromolecules ( IF 5.1 ) Pub Date : 2021-03-15 , DOI: 10.1021/acs.macromol.1c00174
Yuxing Zhang _{1,

2} , Zhongbao Jian _{1,

2}

Affiliation

Branching is paramount in polyolefins and their copolymers because it renders state-of-the-art topologies and thus directly determines polymer properties. A polar additive, commonly acting as a coordinating ancillary ligand in olefin polymerization, is usually a poisonous reagent to shut down the reaction. Also, it is generally assumed to have very little or even no impact on polyethylene (PE) architecture in terms of branching. We now demonstrate the finding that the degree of branching in palladium promoted ethylene polymerization can drastically be switched from ultrahigh branching (>200/1000 C, T_g ∼ −62 °C) to significantly low branching (<10/1000 C, T_m ∼ 125 °C) by acrylonitrile as a polar additive (up to 4000 equiv). Key features that a polar additive does not shut down the reaction and significantly switches the degree of branching and importantly does not induce chain transfer (living mode, PDI < 1.10) readily enable the preparation of diblock topologies of amorphous ultrahighly branched PE and semicrystalline lightly branched PE. A further new concept that acrylate serves as a polar comonomer and acrylonitrile acts as a regulator of branching gives access to functionalized PE with tunable branching degrees.

中文翻译：

活性乙烯聚合中的极性添加剂触发的支化开关和嵌段聚烯烃拓扑

在聚烯烃及其共聚物中，支化是最重要的，因为它提供了最先进的拓扑结构，因此直接决定了聚合物的性能。通常在烯烃聚合反应中充当配位辅助配体的极性添加剂通常是有毒试剂，会终止反应。而且，通常认为在支化方面对聚乙烯（PE）结构几乎没有影响，甚至没有影响。我们现在证实这一发现，在钯促进乙烯聚合支化度可以显着地从超高支化（> 200/1000 C，切换Ť_克〜-62℃）至显著低支化（<10/1000 C，Ť_米约125°C（约125°C），由丙烯腈作为极性添加剂（最高4000当量）。极性添加剂不会关闭反应并显着改变支化程度的重要特征，并且重要的是不会引起链转移（活性模式，PDI <1.10），可以轻松制备无定形超高支链PE和半结晶轻支链的二嵌段拓扑结构PE。丙烯酸酯充当极性共聚单体，丙烯腈充当支化调节剂的另一个新概念使人们能够以可调的支化度获得官能化的PE。

更新日期：2021-04-13

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