Elucidating the Topology and Physical Properties of Triblock Copolymers Using Ion Mobility Mass Spectrometry

Abstract

A combination of electrospray ionization (ESI) and ion mobility mass spectrometry (IMMS) is used to successfully determine the characteristic ratio (Cn) of homopolymers and triblock copolymers. Two different copolymer systems are analyzed: a poly(ethylene glycol)/poly(propylene glycol) (PEG/PPG) and a poly(methyl acrylate)/poly(butyl acrylate) (PMA/PBA) based system. The monomer composition within the copolymers is chosen to be constant while changing the block sequence along the main chain, in order to ensure a reliable determination of the influence of the topology on the physical properties. It can be demonstrated that the block structure has a significant influence on Cn and therefore on the physical properties of the block copolymers. For both systems, the inner block dominates the overall physical properties.

Gas‐phase structure of polymer ions: Tying together theoretical approaches and ion mobility spectrometry

“…For instance, it allows to separate macroions of different topologies, such as cyclic and linear polymers, or shape changes due to ionization by protonation or complexation of alkali/metal ions (Duez, van Huizen, et al, 2019; Haler et al, 2020; Hoskins et al, 2011; Kim et al, 2014; Liénard et al, 2020; Morsa et al, 2014; Tintaru et al, 2014; Trimpin et al, 2007; Trimpin & Clemmer, 2008). Ultimately, the mathematical fitting of CCS “trend lines” enables to derive quantitative data relevant to the investigated polymer, as discussed below (Duez, Liénard, et al, 2019; Frerichs et al, 2021; Haler et al, 2018; Kokubo & Vana, 2017; Ruotolo et al, 2008; Saintmont et al, 2020). This data fitting provides the contribution of each monomer unit to the global CCS (Figure 1).…”

“…The C n values derived from IMS measurements are remarkably close to literature values obtained using solution‐phase characterization methods, such as viscosity measurements (Allen et al, 1967; Beech & Booth, 1969; Kokubo & Vana, 2016; Sasanuma, 1995). This approach was then used to probe the influence of the sequence of triblock copolymers on their C n values (Frerichs et al, 2021).…”