Bifunctional Initiators as Tools to Track Chain Transfer during the CROP of 2‐Oxazolines,Macromolecular Rapid Communications

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Bifunctional Initiators as Tools to Track Chain Transfer during the CROP of 2‐Oxazolines
Macromolecular Rapid Communications ( IF 4.2 ) Pub Date : 2017-08-24 , DOI: 10.1002/marc.201700396
Martin Sahn _{1,

2} , Damiano Bandelli _{1,

2} , Michael Dirauf _{1,

2} , Christine Weber _{1,

2} , Ulrich S. Schubert _{1,

2}

Affiliation

Detailed kinetic studies during the cationic ring‐opening polymerization (CROP) of 2‐ethyl‐2‐oxazoline (EtOx) are conducted using four bifunctional bromo‐type initiators in N,N‐dimethylformamide (DMF) at 140 °C. Serving as models to quantify chain transfer to monomer occurring during the CROP initiated by monofunctional initiators, size exclusion chromatography (SEC) resolves a second molar mass distribution with lower molar mass at initial [monomer] to [initiation site] ratios ([M]₀/[I]₀) of 25, while the resolution is insufficient at [M]₀/[I]₀ of 10. Slightly slow initiation is revealed at [M]₀/[I]₀ = 25, which prohibits the derivation of chain transfer rates by fitting of the size exclusion chromatography (SEC) data. Although conventional kinetic plots give no indication of significant amounts of chain transfer, the molar mass distributions resolved by SEC can unambiguously be identified as such by matrix‐assisted laser desorption/ionization mass spectrometry (MALDI MS) in both the high as well as the low m/z regions of the mass spectra.

中文翻译：

双功能引发剂可作为2-恶唑啉CROP期间追踪链转移的工具

在140°C下，使用四种双官能溴型引发剂在N，N-二甲基甲酰胺（DMF）中对2-乙基-2-恶唑啉（EtOx）进行阳离子开环聚合（CROP）期间进行了详细的动力学研究。尺寸排阻色谱（SEC）用作量化单官能引发剂引发CROP期间发生的链转移至单体的链转移模型，它以初始[单体]与[引发部位]的比率（[M] ₀ / [I] ₀的25），而分辨率是不够的，在[M] ₀ / [I] ₀的10略慢启动显露在[M] ₀ / [I] ₀= 25，它通过拟合尺寸排阻色谱（SEC）数据来禁止推导链转移速率。尽管传统的动力学图没有给出大量链转移的迹象，但可以通过基质辅助激光解吸/电离质谱法（MALDI MS）明确地确定由SEC解析的摩尔质量分布，无论是高质谱还是低质谱质谱的m / z区域。

更新日期：2017-08-24

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