Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, Den Dolech 2, 5612AZ Eindhoven, The Netherlands.
Beilstein J Org Chem. 2010 Sep 9;6:773-83. doi: 10.3762/bjoc.6.96.
The synthesis of well-defined polymer architectures is of major importance for the development of complex functional materials. In this contribution, we discuss the synthesis of a range of multifunctional star-shaped tosylates as potential initiators for the living cationic ring-opening polymerization (CROP) of 2-oxazolines resulting in star-shaped polymers. The synthesis of the tosylates was performed by esterification of the corresponding alcohols with tosyl chloride. Recrystallization of these tosylate compounds afforded single crystals, and the X-ray crystal structures of di-, tetra- and hexa-tosylates are reported. The use of tetra- and hexa-tosylates, based on (di)pentaerythritol as initiators for the CROP of 2-ethyl-2-oxazoline, resulted in very slow initiation and ill-defined polymers, which is most likely caused by steric hindrance in these initiators. As a consequence, a porphyrin-cored tetra-tosylate initiator was prepared, which yielded a well-defined star-shaped poly(2-ethyl-2-oxazoline) by CROP as demonstrated by SEC with RI, UV and diode-array detectors, as well as by ¹H NMR spectroscopy.
具有确定结构的聚合物的合成对于复杂功能材料的发展至关重要。在本研究中，我们讨论了一系列多功能的对甲苯磺酸盐作为潜在的引发剂，用于 2-恶唑啉的活阳离子开环聚合（CROP），得到星型聚合物。对甲苯磺酸盐的合成是通过相应醇与对甲苯磺酰氯的酯化反应来完成的。这些对甲苯磺酸盐化合物经过重结晶得到单晶，并报道了二、四和六对甲苯磺酸盐的 X 射线晶体结构。基于（二）季戊四醇的四和六对甲苯磺酸盐作为 2-乙基-2-恶唑啉的 CROP 的引发剂，引发反应非常缓慢，得到的聚合物结构不明确，这很可能是由于这些引发剂的空间位阻所致。因此，制备了卟啉核的四对甲苯磺酸盐引发剂，通过 SEC 与 RI、UV 和二极管阵列检测器以及 ¹H NMR 光谱证明，该引发剂可以有效地进行 CROP，得到了结构明确的星型聚（2-乙基-2-恶唑啉）。
