High‐Resolution Ion Mobility Spectrometry–Mass Spectrometry on Poly(methyl methacrylate)

Abstract

Synthetic polymers are produced in industry to serve a global market across a wide range of areas. [1a-c] Increasingly complex polymeric structures have been developed to provide desirable properties and functions. [1d] The performance of these products depends on many factors such as endgroup composition, molecular weight distribution (MWD), and 3D conformation. [1e,f] Various analytical methods have been developed to obtain information about these properties. Conventional analytical techniques to study polymer systems include gel-permeation chromatography (GPC), [2a] Fourier-transform IR (FTIR), [2b] NMR spectroscopy, [2c] and differential scanning calorimetry (DSC). [2d] The development of "soft" ionization methods such as elecrospray ionization (ESI) [3a,b] and matrix-assisted laser desorption/ionization (MALDI) [3c,d] allowed mass spectrometry (MS) to become one of the most promising analytical methods for the analysis of polymeric systems. MS has the ability to characterize a dispersed polymer containing oligomers with different structures such as isomers or isobaric molecular weights. The combination of liquid chromatography (LC) and MS reduces the effects of ion suppression that may occur in an infusion MS analysis and provides an extra dimension of separation. [4] However, a relatively long separation time (> 30 min for HPLC, around 10 min for UPLC) is needed and a complex elution system using a variety of solvents has to be developed to suit a specific polymeric system.The combination of ion mobility spectrometry (IMS) and ESI-MS has been developed to analyze biomolecules and biopolymers. [5] Ion mobility describes how fast an ion in the gas phase moves through a drift cell that is filled with a carrier buffer gas under the influence of an electric field. More compact ions with a smaller collision cross-section will drift more quickly than expanded ions. The time-scale for separations in IMS is 100 ms to 10 ms, which is ideally suited for interfacing with an MS instrument. The extra dimension of separation based on drift time (t D ) provided by IMS is also highly complementary to the information obtained by MS. Although some studies on IMS-MS measurements of blends of disperse macromolecules, for example, poly(ethylene glycol) (PEG), have been reported, studies using IMS-MS on complex synthetic polymer systems are still limited. [6] Here, we demonstrate the power of using high resolution IMS-MS to study a poly(methyl methacrylate) (PMMA) synthesized by radical polymerization using peroxide initiator (tert-butyl peroxy-3,5,5-trimethylhexanoate) in solvent. Comprehensive studies on acrylic polymer produced by radical polymerization using MS have been done in the past decade. [7] It has been proven that high-resolution MS can discriminate between the effects of various polymerization mechanisms such as b-scission, chain transfer to solvent, radical transfer to solvent from the initiator, etc. [7] A system with complex endgroup combinations is expected since various initiation and termination ...

The use of stable carbene‐CO2 adducts for the polymerization of trimethylene carbonate

“…To accomplish this further separation is needed. Besides size exclusion chromatography coupled to mass spectrometry, a lesser known method called ion mobility separation can be used . This allows separation of ions in accordance with their shape and size in addition to mass analysis.…”

“…With this method two‐dimensional m / z versus drift time diagrams (see Figure ) were obtained from which single regions can be selected ( A–E ) . Hence, mass spectra of uniformly charged polymers can be obtained as seen in Figure where end group analysis is possible.…”

Tetraphenylethylene-Based Emissive Supramolecular Metallacages Assembled by Terpyridine Ligands

“…Moreover, all the different charge states revealed by TWIM-MS spectrum had narrow drift time distribution, which indicated that no overlapping isomers or structural conformers were generated (Figure 3b) . 63,[69][70][71][72][73][74][75][76] (Figure 3c). Each peak was in an excellent agreement with the corresponding theoretical isotope pattern (Supporting Information Figure S22).…”

“…ESI-MS and TWIM-MS were used to validate further the molecular compositions of the metallacages. 63,69 For cage [Zn 6 LA 3 ], only one set of peaks with different charge states (5+ to 10+) were observed with successive loss of the corresponding PF 6 − counterions (Figure 3a). Figure S21).…”

Ion mobility spectrometry – Mass spectrometry coupling for synthetic polymers

“…Separation of (nearly) isobaric ions by IMS can be performed to improve the accuracy of their mass measurements, as reported for example by Song et al who used TWIMS to separate PMMA oligomers with different end‐groups in order to best measure the largest m/z ions that were not well‐resolved by FT‐ICR . However, the most usual motivation for separation of isomeric or isobaric polymeric species is undoubtedly acquisition of reliable MS/MS data, where IMS‐resolved ions can be activated individually in the collision cell located after the mobility cell, as typically allowed by the TWIMS instrument configuration.…”