Organic Synthesis and Mass Spectrometry Laboratory, Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons (UMONS), Place du Parc 23, B-7000 Mons, Belgium.
Laboratory for Chemistry of Novel Materials, Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons (UMONS), Place du Parc 23, B-7000 Mons, Belgium.
J Am Soc Mass Spectrom. 2020 Nov 4;31(11):2379-2388. doi: 10.1021/jasms.0c00352. Epub 2020 Oct 12.
Synthetic polymers occupy a unique place in the field of ion mobility mass spectrometry (IMS-MS). Indeed, due to their intrinsic dispersity, they have the asset to offer a broad range of homologous ions with different lengths that can be detected in several charge states. In addition, the gas-phase structure of polymer ions mostly depends on their ability to screen the adducted charges. Several works dealing with linear, cyclic, and star-shaped polymers have already shown that the gas-phase structure of polymer ions heavily relies on the polymer architecture, i.e., the primary structure. In the present work, we move a step further by evaluating whether a relationship exists between the primary and secondary structures of synthetic homo and copolymers. The IMS-MS experiments will be further complemented by MD simulations. To highlight the effectiveness of IMS separation, we selected isomeric homo and copolymers made of lactide (LA) and propiolactone (PL) units. In this way, the mass analysis becomes useless since isomeric comonomer sequences can coexist for any given chain length. An UPLC method was implemented in the workflow to successfully separate all PL-LA comonomer sequences before infusion in the IMS-MS instrument. The analysis of doubly charged copolymers showed that the comonomer sequence has an impact on the IMS response. However, this only holds for copolymer ions with precise sizes and charge states, and this is therefore not a rule of thumb.
合成聚合物在离子淌度质谱（IMS-MS）领域占据着独特的地位。事实上，由于其内在的分散性，它们具有提供一系列不同长度的同源离子的优势，这些离子可以在多个电荷态下被检测到。此外，聚合物离子的气相结构主要取决于它们屏蔽加合电荷的能力。已经有一些关于线性、环状和星形聚合物的工作表明，聚合物离子的气相结构在很大程度上取决于聚合物的结构，即一级结构。在本工作中，我们更进一步评估了合成均聚物和共聚物的一级和二级结构之间是否存在关系。IMS-MS 实验将进一步补充以 MD 模拟。为了突出 IMS 分离的有效性，我们选择了由丙交酯（LA）和丙炔酸内酯（PL）单元组成的异构均聚物和共聚物。这样一来，由于任何给定链长都可能存在异构共聚单体序列，质量分析就变得毫无用处了。在工作流程中实现了 UPLC 方法，成功地分离了在 IMS-MS 仪器中注入之前的所有 PL-LA 共聚单体序列。对二价共聚物的分析表明，共聚单体序列对 IMS 响应有影响。然而，这仅适用于具有精确大小和电荷态的共聚物离子，因此这不是一个普遍规律。
