This review covers the application of mass spectrometry (MS) and its hyphenated techniques to synthetic polymers of varying architectural complexities. The synthetic polymers are discussed as according to their architectural complexity from linear homopolymers and copolymers to stars, dendrimers, cyclic copolymers and other polymers. MS and tandem MS (MS/MS) has been extensively used for the analysis of synthetic polymers. However, the increase in structural or architectural complexity can result in analytical challenges that MS or MS/MS cannot overcome alone. Hyphenation to MS with different chromatographic techniques (2D × LC, SEC, HPLC etc.), utilization of other ionization methods (APCI, DESI etc.) and various mass analyzers (FT-ICR, quadrupole, time-of-flight, ion trap etc.) are applied to overcome these challenges and achieve more detailed structural characterizations of complex polymeric systems. In addition, computational methods (software: MassChrom2D, COCONUT, 2D maps etc.) have also reached polymer science to facilitate and accelerate data interpretation. Developments in technology and the comprehension of different polymer classes with diverse architectures have significantly improved, which allow for smart polymer designs to be examined and advanced. We present specific examples covering diverse analytical aspects as well as forthcoming prospects in polymer science.

We report the synthesis and characterization of welldefined homo-and diblock copolymers containing poly(furfuryl glycidyl ether) (PFGE) via living anionic ring-opening polymerization using different initiators. The obtained materials were characterized by SEC, MALDI-TOF MS, and 1 H NMR spectroscopy and molar masses of up to 9400 g/mol were obtained for PFGE homopolymers. If the amphiphilic diblock copolymer PEG-block-PFGE was dissolved in water, micelles with a PFGE core and a PEG corona were formed. Hereby, the hydrophobic PFGE core domains were used for the incorporation of a suitable bismaleimide and heating to 60 C induced the crosslinking of the micellar core via Diels-Alder chemistry. This process was further shown to be reversible. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: [4958][4959][4960][4961][4962][4963][4964][4965] 2012

The preparation of redox-active polymers and the chainend functionalization with one ruthenium complex was investigated in detail. A series of substituted monomers, i.e., styrenic triarylamines bearing methyl, fluoro, or methoxy substituents, were prepared by a one-pot Hartwig−Buchwald coupling. The nitroxide-mediated polymerization (NMP) was studied by variation of the functional initiators, the monomer-to-initiator ratios, and the solvent. The kinetic analysis of the prototypical methyl-substituted triarylamine shows the controlled polymerization up to 75% conversion, but a considerable decrease of the polymerization rate was observed during the course of the reaction. Both chain-end functionalities of the purified oligomers were subsequently utilized, i.e., the nitroxide to serve as a macroinitiator for an additional NMP step and the chloromethyl group to introduce one ruthenium complex at the chain terminus. The products were analyzed in detail by size-exclusion chromatography, NMR spectroscopy, and mass spectrometry. The optical and electrochemical properties of the prepared poly(triarylamine)s show the application potential as charge transport materials in conjunction with the photoactive ruthenium complex.

The accurate characterization of synthetic polymer sequences represents a major challenge in polymer science. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is frequently used for the characterization of copolymer samples. We present the COCONUT software for estimating the composition distribution of the copolymer. Our method is based on Linear Programming and is capable of automatically resolving overlapping isotopes and isobaric ions. We demonstrate that COCONUT is well suited for analyzing complex copolymer MS spectra. COCONUT is freely available and provides a graphical user interface.

Abstract:We demonstrate the synthesis of star-shaped poly(ethylene oxide)-block-poly(2-ethyl-2-oxazoline) [PEO m -b-PEtOx n ] x block copolymers with eight arms using two different approaches, either the "arm-first" or the "core-first" strategy. Different lengths of the outer PEtOx blocks ranging from 16 to 75 repeating units were used, and the obtained materials [PEO 28 -b-PEtOx x ] 8 were characterized via size exclusion chromatography (SEC), nuclear magnetic resonance spectroscopy (NMR), and Fourier-transform infrared spectroscopy (FT-IR) measurements. First investigations regarding the solution behavior in water as a non-selective solvent revealed significant differences. Whereas materials synthesized via the "core-first" method seemed to be well soluble (unimers), aggregation occurred in the case of materials synthesized by the "arm-first" method using copper-catalyzed azide-alkyne click chemistry.

A simple and convenient method for the synthesis of end functionalized polylactides (PLAs) under mild conditions by ring opening polymerization (ROP) in the absence of potentially toxic catalysts is described. Various alcohols were used as initiators in combination with Ca[N(SiMe3)2]2(THF)2 as the precatalyst in THF at room temperature. Tailored end functionalities were obtained in a controlled fashion. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐ToF‐MS) and electrospray ionization quadrupole time of flight mass spectrometry (ESI‐Q‐ToF‐MS) analysis were performed to investigate the end groups. The results confirmed that the end group fidelity was maintained in the isolated PLAs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 437–448

In this contribution, the cationic ring-opening polymerization (CROP) and copolymerization of 2-ethyl-2-oxazoline and 2-tert-butyl-2-oxazoline using a strong cationic Brønsted acid, [H(OEt 2 ) 2 ][Al {OC(CF 3 ) 3 } 4 ], as an initiator are described. First, various poly(2-ethyl-2-oxazoline) (PEtOx) samples are prepared and the living/controlled character of the reaction is demonstrated. We could show that the microwave-assisted CROP of EtOx using this initiator system proceeds faster if compared to classical initiators such as methyl tosylate. These results were then extended to the CROP of poly(2-tertbutyl-2-oxazoline) (PtButOx) and to PEtOx/PtButOx random and block copolymers of different compositions. The resulting materials were characterized using spectroscopic ( 1 H-NMR, FT-IR), chromatographic (SEC), and thermoanalytic techniques (DSC, TGA). Although samples containing more than 13 wt% PtButOx were insoluble in common organic solvents, thermogravimetric (TGA, DSC), spectroscopic (IR), scattering methods (wide-angle X-ray scattering, WAXS), and SEC in hexafluoro-iso-propanol (HFIP) hinted at the successful formation of block copolymers. In particular, WAXS revealed increasing crystallinity for samples containing higher weight fractions of PtButOx.

We demonstrate the synthesis of star-shaped poly(2-ethyl-2-oxazoline) featuring a porphyrin core starting from alkyne-functionalized porphyrin ([TPP-TB]4) and azide-functionalized poly(2-ethyl-2-oxazoline) (PEtOx-N3) via copper-catalyzed azide-alkyne cycloaddition (CuAAC). The porphyrin core was further utilized for the complexation of either copper or iron within the central cavity. The obtained materials were investigated using a combination of nuclear magnetic resonance spectroscopy, fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, size-exclusion chromatography, and matrix assisted laser desorption/ionization time-of-flight mass spectrometry. In the case of copper, the inclusion of the metal ion was achieved in a one-pot reaction during the CuAAC reaction for attaching the PEtOx-N3 arms.