scholarly journals Determining the effect of side reactions on product distributions in RAFT polymerization by MALDI-TOF MS

2015 ◽  
Vol 6 (30) ◽  
pp. 5437-5450 ◽  
Author(s):  
Antonio Veloso ◽  
Wendy García ◽  
Amaia Agirre ◽  
Nicholas Ballard ◽  
Fernando Ruipérez ◽  
...  
Keyword(s):  
Radical Polymerization ◽  
Raft Polymerization ◽  
Side Reactions ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Product Distributions ◽  
Wide Range ◽  
Reversible Deactivation ◽  
Reversible Deactivation Radical Polymerization ◽  
Tof Ms

RAFT polymerization has emerged as one of the most versatile reversible deactivation radical polymerization techniques and is capable of polymerizing a wide range of monomers under various conditions.

scholarly journals Optimized MALDI-TOF MS Strategy for Characterizing Polymers

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhenxin Wang ◽  
Quanqing Zhang ◽  
Huali Shen ◽  
Pengyuan Yang ◽  
Xinwen Zhou
Keyword(s):  
Mixing Ratio ◽  
Preparation Methods ◽  
Ionization Time ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Flight Mass Spectrometry ◽  
Wide Range ◽  
Cationization Reagent ◽  
Polyether Polyol ◽  
Tof Ms

In recent years, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) plays an essential role in the analysis of polymers. To acquire a more reliable strategy for polymer profiling, we characterized four representative polymers including polyethylene glycol 6000, polyvinylpyrrolidone K12, polymer polyol KPOP-5040, and polyether polyol DL-4000. The preparation methods of these four polymer samples have been optimized from six aspects, including matrix, cationization reagent, solvent, mixing ratio of cationization reagent to polymer, mixing ratio of matrix to polymer, and laser intensity. After investigating the effects of seven commonly used matrices on the ionization efficiency of four polymers, trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene] malononitrile (DCTB) was found to be the only matrix suitable for the analysis of all the four polymers. Our experimental results suggested that different polymers showed a certain preference for different cationization reagents. For example, the polymer polyol KPOP-5040 was suitable for sodium iodide as the cationization reagent, while polyvinylpyrrolidone K12 was more suitable for silver trifluoroacetate (AgTFA). For the choice of solvent, tetrahydrofuran is a reagent with rapid evaporation and a wide range of dissolution which can achieve the best results for the analysis of four polymers. The optimized method was successfully applied to the identification of DSPE-PEG-NH2 with different polymerized degrees. This MALDI-TOF strategy potentially provided the supplementary function through the polymer’s application in biomedical and visible probing.

scholarly journals Chronic Rhinosinusitis: MALDI-TOF Mass Spectrometry Microbiological Diagnosis and Electron Microscopy Analysis; Experience of the 2nd Otorhinolaryngology Clinic of Cluj-Napoca, Romania

2020 ◽  
Vol 9 (12) ◽  
pp. 3973
Author(s):  
Ionuț Isaia Jeican ◽  
Lucian Barbu Tudoran ◽  
Adrian Florea ◽  
Mirela Flonta ◽  
Veronica Trombitas ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mass Spectrometry ◽  
Chronic Rhinosinusitis ◽  
Sinus Surgery ◽  
Microbiological Diagnosis ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Wide Range ◽  
Tof Ms ◽  
Scanning Electron

(1) Background: Chronic rhinosinusitis (CRS) represents a wide range of infectious-inflammatory processes affecting, simultaneously, the nose and paranasal sinuses mucosa. The paper presents outcomes of the investigation of CRS microbiological characteristics in a group of 32 patients. (2) Methods: The purulent samples were collected during functional endoscopic sinus surgery. Agar plates were incubated and examined. All types of colonies were identified using Matrix-Assisted Laser Desorption - Ionisation-Time of Flight Mass Spectrometry (MALDI-TOF MS). For scanning electron microscopy, samples were fixed and sputter-coated with 10 nm gold and analyzed using a scanning electron microscope. For transmission electron microscopy, samples were fixed, postfixed, and dehydrated. After polymerization, ultrathin sections were collected on carbon coated copper grids and analyzed with Jeol JEM1010 TEM. (3) Results: Positive microbiological diagnosis was obtained in 62.5% of cases. The most frequent species found are Staphylococcus aureus and Streptococcus constellatus subsp. pharyngis. Corynebacterium aurimucosum and Eggerthia catenaformis were unreported species in CRS until the present. Biofilm was evidenced in 43.7% of sinus mucosa samples. Ciliary disorientation, atrophy, and no ciliated cells were also identified. (4) Conclusion: The microbial factor—pathogen or opportunistic—is one of the most important pathological links in chronic rhinosinusitis. MALDI-TOF MS allows easily and quickly identification of germs.

scholarly journals Characterization of aliphatic hyperbranched polyesters by MALDI-TOF mass spectrometry

2007 ◽  
Vol 61 (6) ◽  
pp. 333-341
Author(s):  
Jasna Vukovic ◽  
Slobodan Jovanovic ◽  
Manfred Lechner
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Degree Of Polymerization ◽  
Side Reactions ◽  
Maldi Tof Ms ◽  
Hyperbranched Polyesters ◽  
Maldi Tof ◽  
Maldi Tof Mass Spectra ◽  
Tof Ms

In this work, MALDI-TOF mass spectrometry was used for the characterization of aliphatic hyperbranched polyesters (AHBP), synthesized from 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) and di-trimethylolpropane. From the obtained results it was concluded that it was not possible to take complete advantages of MALDI-TOF MS in this particular case, since the AHBP used in this work were polydisperse. The intensity of the signals from the high mass tail of these samples (pseudo generation higher than four) was underestimated and insufficient to distinguish it from the baseline and to use it for the analysis of the spectra. As a consequence of that, lower values of the Mn were obtained. At the same time, Mw were also underestimated, which led to very low values of the polydispersity index. On the other hand, it was possible to obtain molar masses of individual molecules from the MALDI-TOF mass spectra of AHBP and to qualitatively determine the extent of cyclization (side reactions) at each degree of polymerization. Using the adequate set of equations and results obtained from MALDI-TOF mass spectra of AHBP, every signal from the spectra was identified. The obtained results show that formation of poly(bis-MPA), intramolecular esterification and intramolecular etherification occurred as side reactions during the synthesis of these polyesters. The relative amount of the cycles increases with the number of pseudo generation (from the second up to the fifth pseudo generation). It was also observed that the relative proportion of the signals which represent cyclic structures increases with the increasing degree of polymerization. In this work the basic principles of MALDI-TOF MS are also presented, as well as, a review of adequate published articles.

scholarly journals Phenotypic and Genotypic Characterization with MALDI-TOF-MS Based Identification of Staphylococcus spp. Isolated from Mobile Phones with their Antibiotic Susceptibility, Biofilm Formation, and Adhesion Properties

2020 ◽  
Vol 17 (11) ◽  
pp. 3761 ◽  
Author(s):  
Emira Noumi ◽  
Abderrahmen Merghni ◽  
Mousa Alreshidi ◽  
Rosa Del Campo ◽  
Mohd Adnan ◽  
...  
Keyword(s):  
Mobile Phones ◽  
Meca Gene ◽  
Hydrolytic Enzymes ◽  
Adhesion Properties ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Wide Range ◽  
The Matrix ◽  
Staphylococcus Spp ◽  
Tof Ms

Cell phones, smartphones, and tablets are extensively used in social and professional life, so they are frequently exposed to bacteria. The main goal of the present work was to isolate and characterize Staphylococci strains from students’ cell phone mobiles. Subsequently, 24 Staphylococci strains were tested against a wide range of antibiotics, for the distribution of some virulence-related genes and their ability to form biofilm. Staphylococcus spp. were cultured from all studied devices on chromogenic medium and identified using the matrix-assisted laser desorption/ionization (MALDI), time-of-flight (TOF) mass spectrometry (MS) technique (MALDI-TOF-MS). The results obtained showed that S. aureus was the dominant species (19 strains, 79.1%), followed by S. warneri (3 strains, 12.5%), and S. haemolyticus (2 strains, 8.3%). Isolated strains showed high percentages of hydrolytic enzymes production, resistance to many tested antibiotics, and 37.5% expressed the mecA gene. The tested strains were highly adhesive to polystyrene and glass and expressed implicated icaA (62.5%) and icaD (66.6%) genes. All Staphylococcus spp. strains tested were found to possess proteases and the α-hemolysin gene. Our results highlighted the importance of mobile phones as a great source of Staphylococcus spp., and these species were found to be resistant to many antibiotics with multiple antibiotic resistance (MAR) index ranging from (0.444) to (0.812). Most of the studied strains are able to form biofilm and expressed many virulence genes. Phylogenetic analysis based on the phenotypic and genetic characters highlighted the phenotypic and genetic heterogeneity of the S. aureus population studied. Further analyses are needed to elucidate the human health risks associated with the identified Staphylococci strains.

scholarly journals ABC-Type Triblock Copolyacrylamides via Copper-Mediated Reversible Deactivation Radical Polymerization

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 116
Author(s):  
Fehaid M. Alsubaie ◽  
Othman Y. Alothman ◽  
Hassan Fouad ◽  
Abdel-Hamid I. Mourad
Keyword(s):  
Radical Polymerization ◽  
Triblock Copolymers ◽  
Side Reaction ◽  
Side Reactions ◽  
One Pot ◽  
Functional Monomers ◽  
Reversible Deactivation ◽  
Living Nature ◽  
Reversible Deactivation Radical Polymerization ◽  
High Degree

The aqueous Cu(0)-mediated reversible deactivation radical polymerization (RDRP) of triblock copolymers with two block sequences at 0.0 °C is reported herein. Well-defined triblock copolymers initiated from PHEAA or PDMA, containing (A) 2-hydroxyethyl acrylamide (HEAA), (B) N-isopropylacrylamide (NIPAM) and (C) N, N-dimethylacrylamide (DMA), were synthesized. The ultrafast one-pot synthesis of sequence-controlled triblock copolymers via iterative sequential monomer addition after full conversion, without any purification steps throughout the monomer additions, was performed. The narrow dispersities of the triblock copolymers proved the high degree of end-group fidelity of the starting macroinitiator and the absence of any significant undesirable side reactions. Controlled chain length and extremely narrow molecular weight distributions (dispersity ~ 1.10) were achieved, and quantitative conversion was attained in as little as 52 min. The full disproportionation of CuBr in the presence of Me6TREN in water prior to both monomer and initiator addition was crucially exploited to produce a well-defined ABC-type triblock copolymer. In addition, the undesirable side reaction that could influence the living nature of the system was investigated. The ability to incorporate several functional monomers without affecting the living nature of the polymerization proves the versatility of this approach.

scholarly journals Living Radical Polymerization by the RAFT Process - A Second Update

2009 ◽  
Vol 62 (11) ◽  
pp. 1402 ◽  
Author(s):  
Graeme Moad ◽  
Ezio Rizzardo ◽  
San H. Thang
Keyword(s):  
Radical Polymerization ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Diverse Range ◽  
Reversible Addition ◽  
Reversible Deactivation ◽  
Modified Surfaces ◽  
Diagnostic Applications ◽  
Reversible Deactivation Radical Polymerization ◽  
End Group

This paper provides a second update to the review of reversible deactivation radical polymerization achieved with thiocarbonylthio compounds (ZC(=S)SR) by a mechanism of reversible addition–fragmentation chain transfer (RAFT) that was published in June 2005 (Aust. J. Chem. 2005, 58, 379–410). The first update was published in November 2006 (Aust. J. Chem. 2006, 59, 669–692). This review cites over 500 papers that appeared during the period mid-2006 to mid-2009 covering various aspects of RAFT polymerization ranging from reagent synthesis and properties, kinetics and mechanism of polymerization, novel polymer syntheses and a diverse range of applications. Significant developments have occurred, particularly in the areas of novel RAFT agents, techniques for end-group removal and transformation, the production of micro/nanoparticles and modified surfaces, and biopolymer conjugates both for therapeutic and diagnostic applications.

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