Schüttner Sandra, Lu Yiye, Frey Holger, Coates Geoffrey W
Department of Chemistry, Johannes Gutenberg University, 55128, Mainz, Germany.
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY, 14853, USA.
Angew Chem Int Ed Engl. 2025 Jan 2;64(1):e202413643. doi: 10.1002/anie.202413643. Epub 2024 Nov 11.
Polymer stereocomplex formation represents a promising research area as it can improve thermal and mechanical properties of co-crystallized polymer strands of opposite chirality. Polymers that form stereocomplexes commonly feature high stereoregularity and usually require sourcing from enantiopure monomer building blocks. Herein, we report the in situ polyether stereocomplex formation from racemic epoxide monomers, i.e., substituted methyl phenyl glycidyl ethers. The bio-renewable glycidyl ethers were explored in both enantio- and isoselective ring-opening polymerizations (ROPs), resulting in isotactic poly(phenyl glycidyl ether). While the enantioselective ROP selectively resolves a single enantiomeric, isotactic polyether stereoisomer ([mm]≥78 %), the isoselective ROP leads to the concurrent formation of both isotactic (R)- and (S)-poly(phenyl glycidyl ether) stereoisomers ([mm]≥92 %) and thus results directly in a stereoisomer blend, which forms a stereocomplex. This is one of only a few polymer stereocomplexes generated directly during polymerization from a racemic monomer mixture. Stereocomplexes of the different poly(phenyl glycidyl ether)s show an increase in melting temperature of up to 76 °C, relative to the enantiopure parent polymers. The position of the methyl group at the phenyl ring determines both stereocomplex formation and the thermal properties of the resulting materials.
聚合物立体络合物的形成是一个很有前景的研究领域，因为它可以改善具有相反手性的共结晶聚合物链的热性能和机械性能。形成立体络合物的聚合物通常具有高立构规整性，并且通常需要从对映体纯的单体结构单元中获取。在此，我们报道了由外消旋环氧化物单体，即取代的甲基苯基缩水甘油醚原位形成聚醚立体络合物。在对映选择性和等规选择性开环聚合（ROP）中都研究了生物可再生缩水甘油醚，得到了全同立构聚（苯基缩水甘油醚）。对映选择性ROP选择性地拆分出单一的对映体全同立构聚醚立体异构体（[mm]≥78%），而等规选择性ROP导致同时形成全同立构的（R）-和（S）-聚（苯基缩水甘油醚）立体异构体（[mm]≥92%），从而直接得到一种立体异构体共混物，该共混物形成了立体络合物。这是仅有的少数几种由外消旋单体混合物在聚合过程中直接生成的聚合物立体络合物之一。不同的聚（苯基缩水甘油醚）的立体络合物相对于对映体纯的母体聚合物，熔点升高高达76℃。苯环上甲基的位置决定了立体络合物的形成以及所得材料的热性能。
