Odenwald Lukas, Wimmer Florian P, Mast Nina K, Schußmann Max G, Wilhelm Manfred, Mecking Stefan
Chair of Chemical Materials Science, Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany.
Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany.
J Am Chem Soc. 2022 Jul 27;144(29):13226-13233. doi: 10.1021/jacs.2c03778. Epub 2022 Jul 15.
Vitrimers can combine the advantageous properties of cross-linked materials with thermoplastic processability. For the prominent case of polyethylene, established post-polymerization introduction of cross-linkable moieties results in extremely heterogeneous compositions of the chains. Here, we report the generation of functionalized polyethylenes directly by catalytic insertion polymerization, with incorporated cross-linkable aryl boronic esters or alternatively acetal-protected groups suited for cross-linking with difunctional boronic esters. In addition to the desired homogeneous in-chain distribution, the reactive cross-linkable groups are enriched at the chain ends. This enables the incorporation of all chains in the network, as also supported by simulations of all chains' compositions. The uniform molecular composition of the chains reflects in resulting vitrimers' material properties, particularly lack of leaching with solvents. At the same time, cross-linking is indeed fully reversible and the vitrimers can be recycled.
热致互穿聚合物网络材料可以将交联材料的有利特性与热塑性加工性能结合起来。对于聚乙烯这种典型例子，已有的后聚合引入可交联部分会导致链的组成极其不均匀。在此，我们报道了通过催化插入聚合直接生成功能化聚乙烯，其中引入了可交联的芳基硼酸酯或适用于与双功能硼酸酯交联的缩醛保护基团。除了所需的链内均匀分布外，反应性可交联基团在链端富集。这使得所有链都能纳入网络，这也得到了所有链组成模拟的支持。链的均匀分子组成反映在所得热致互穿聚合物网络材料的性能上，特别是在溶剂中不发生浸出。同时，交联确实是完全可逆的，热致互穿聚合物网络材料可以回收利用。
