Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstr. 10, 07743, Jena, Germany.
Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743, Jena, Germany.
Macromol Rapid Commun. 2019 Jun;40(12):e1900094. doi: 10.1002/marc.201900094. Epub 2019 Apr 10.
During the last decades, poly(2-oxazoline)s (POx) have gained increased interest due to their versatility. In particular, cationic ring-opening polymerization (CROP) enables the synthesis of well-defined polymers bearing quantitative α- and ω-functionalities. In contrast to small initiating groups, the introduction of more sophisticated, respectively demanding groups remains challenging. To fulfill this challenge, the initiator should comply with one major requirement in order to yield well-defined polymers: a fast and complete initiation. The straight forward two-step synthesis of a novel initiator containing a 4-(trifluoromethyl)benzenesulfonate (fluorylate, TosCF ) counter-ion is herein presented to accomplish the introduction of a sophisticated functional 3-(2-(2-ethoxy)ethoxy)ethoxy)prop-1-ene (TEG) initiating group. Kinetic studies are conducted in acetonitrile and chlorobenzene using the hydrophilic 2-ethyl-2-oxazoline (EtOx) as well as the hydrophobic 2-octyl-2-oxazoline (OctOx) as monomers to examine the influences of the solvent as well as the different monomers. In particular, the initiator efficiency is determined by H and F nuclear magnetic resonance spectroscopy and compared to the corresponding tosylate (TEGTos) and triflate (TEGTf). It is shown that the fluorylate combines the stability of the tosylate and an enhanced propagation rate comparable to the triflate.
在过去的几十年中，由于其多功能性，聚（2-恶唑啉）（POx）引起了越来越多的关注。特别是，阳离子开环聚合（CROP）能够合成具有定量α-和ω-官能度的定义明确的聚合物。与小引发基团相比，引入更复杂、要求更高的基团仍然具有挑战性。为了应对这一挑战，引发剂应符合一个主要要求，以产生具有明确结构的聚合物：快速且完全的引发。本文提出了一种新颖的引发剂的两步直接合成方法，该引发剂含有 4-（三氟甲基）苯磺酸盐（fluorylate， TosCF3）抗衡离子，旨在引入复杂的功能性 3-（2-（2-乙氧基）乙氧基）乙氧基）丙-1-烯（TEG）引发基团。在乙腈和氯苯中进行动力学研究，分别使用亲水性 2-乙基-2-恶唑啉（EtOx）和疏水性 2-辛基-2-恶唑啉（OctOx）作为单体，以考察溶剂以及不同单体的影响。特别是，通过 1H 和 19F 核磁共振光谱法测定了引发剂效率，并与相应的对甲苯磺酸盐（TEGTos）和三氟甲磺酸酯（TEGTf）进行了比较。结果表明，fluorylate 结合了 tosylate 的稳定性和与三氟甲磺酸酯相当的增强的聚合速率。
