Systematic MALDI‐TOF CID Investigation on Different Substituted mPEG 2000

Abstract

Methoxy poly(ethylene glycol) 2000 (mPEG 2000) samples were substituted via esterification reactions to convert the hydroxyl end group of the mPEG into potential initiators for the cationic ring opening polymerization of 2‐oxazolines. These substitution products were investigated by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS); in addition, detailed MALDI‐TOF/TOF‐collision induced dissociation (CID) MS studies were performed to introduce this method as complementary structural characterization tool allowing the detailed analysis of the prepared macromolecules. The CID of the macroinitiators revealed 1,4‐hydrogen and 1,4‐ethylene eliminations forming very regular fragmentation patterns which showed, depending on the end groups, different fragmentation series. Furthermore, very pronounced McLafferty + 1 rearrangements (1,5 hydrogen‐transfer) of the introduced ester end groups were observed leaving the mPEG molecule as neutral acid. This incisive loss revealed the exact molar mass for each end group and, therefore, represents an important tool for end group determination of functionalized polymers.magnified image

Tandem Mass Spectrometry for Polymeric Structure Analysis: A Comparison of Two Common MALDI–ToF/ToF Techniques

“…As polymer synthesis techniques advance to enable more complex and controlled macromolecular architecture, so too must the analytical techniques used to probe such architecture. Tandem mass spectrometry has been utilized in tackling this challenge, showing success in probing microstructure, end‐group determination, backbone modifications, branching, and other macromolecular structures . The field of “polymeromics” is expanding; however, this is not as well developed as neighboring fields such as proteomics and petroleomics.…”

Analysis of different synthetic homopolymers by the use of a new calculation software for tandem mass spectra

“…In addition, the following series Z , Y , N , I , K and O could be assigned as fragmentation possibilities to the investigated homopolymers. Belonging to the side product, series Z can be explained by the neutral loss of the ester end group during a McLafferty +1 rearrangement (1,5‐hydrogen transfer) to form a NHCH = CH 2 end group . Due to single main chain fragmentation of the backbone between the CH 2 groups the fragmentation series N can be formed.…”

Synthesis and Solution Properties of Double Hydrophilic Poly(ethylene oxide)-block-poly(2-ethyl-2-oxazoline) (PEO-b-PEtOx) Star Block Copolymers

“…All other chemicals were used as purchased if not otherwise mentioned in the text. 28 -OH] 8 The tosylation of [PEO 28 -OH] 8 (6 g; 0.6 mmol) was achieved in a slightly modified way as described in the literature [44,45]. Briefly, the educts were dissolved in DCM and stirred at room temperature for at least 72 h, obtaining [PEO 28 -Ts] 8 ; Ð = 1.12 (PS-calibration); SEC (DMAC/LiCl): M n = 3900 g mol ; Ð = 1.14 (PS-calibration); 1 H NMR (300 MHz, CDCl 3 , δ): 4.0-3.0 (br, backbone), 2.6-2.2 (br, CO-CH2-CH3), 1.2-0.8 (br, CO-CH 2 -CH 3 ).…”

“…For this purpose, the hydroxyl end group was tosylated first by a nucleophilic substitution reaction using p-toluenesulfonyl chloride (Ts-Cl; Scheme 1), obtaining [PEO-Ts] 8 . Whereas this modification for linear PEO is often described as being performed within a few hours [44,45], in our case, the reaction time needed to be increased to at least 72 h at room temperature to achieve full functionalization (determined via 1 H-NMR; Figure S1C). Figure S1C).…”