Oh Joongsuk, Kuk Jiae, Lee Taeheon, Ye Jihwa, Paik Hyun-Jong, Lee Hyo Won, Chang Taihyun
Department of Chemistry and Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea.
Department of Polymer Science and Engineering, Pusan National University, Busan, 46241, Korea.
ACS Macro Lett. 2017 Jul 18;6(7):758-761. doi: 10.1021/acsmacrolett.7b00447. Epub 2017 Jun 26.
Living and dead chains of a polystyrene synthesized by atom transfer radical polymerization were separated and characterized by high performance liquid chromatography (HPLC), size exclusion chromatography (SEC), NMR, and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The bromine end group in the living chain was quantitatively converted to a hydroxyl end group via first azidation and subsequent copper-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction with propargyl alcohol. The living chains bearing a polar end group are fully resolved from the unmodified dead chains by HPLC separation using a bare silica stationary phase. Molecular weight distributions (MWD) of the living and dead chain are characterized by SEC and MALDI-MS. The MWD of the living chains is close to a Poisson distribution. Interestingly, the elution peak of the living chains in the HPLC separation split into two. The peak split is attributed to the diastereomeric structure of the chain end by NMR and MALDI-MS analyses.
通过原子转移自由基聚合合成的聚苯乙烯的活性链和死链通过高效液相色谱（HPLC）、尺寸排阻色谱（SEC）、核磁共振（NMR）和基质辅助激光解吸/电离质谱（MALDI-MS）进行分离和表征。活性链中的溴端基首先通过叠氮化定量转化为羟基端基，随后与炔丙醇进行铜催化的叠氮化物-炔烃环加成（CuAAC）点击反应。使用裸硅胶固定相通过HPLC分离，带有极性端基的活性链与未改性的死链完全分离。活性链和死链的分子量分布（MWD）通过SEC和MALDI-MS进行表征。活性链的MWD接近泊松分布。有趣的是，HPLC分离中活性链的洗脱峰分裂成两个。通过NMR和MALDI-MS分析，峰分裂归因于链端的非对映异构结构。
