No abstract

The synthesis of telechelic poly(ether sulfone)s with methoxy end groups is reported. Molecular weights ranging from 1600 to 2800 g mol−1 and polydispersities of 1.1–1.2 are synthesized by chain‐growth condensation polymerization. The initiator is chosen by using semiempirical calculations and 19F NMR spectroscopy measurements. The polymers are characterized by NMR spectroscopy and matrix‐assisted laser desorption/ionization time of flight (MALDI‐TOF) mass spectrometry (MS), and are terminated by a methoxy group at one end and a fluorine at the other, and up to approximately 20% polymer of similar mass but slightly higher polydispersity, methoxy terminated at both ends, is present, along with less than 5% of polymer terminated at both ends by fluorine atoms. These do not need to be separated, and can be converted to methoxy‐ending telechelic blocks, yielding polyvalent, reactive rigid building blocks for copolymer synthesis.

Methemoglobinemia is a common complication of dapsone poisoning. Its´ treatment usually relies on methylene blue infusion. The aim of this study was to report a case of an acute dapsone poisoning with methemoglobinemia treated only with ascorbic acid and activated charcoal. A 16-year-old female voluntary ingested 3 grams of dapsone in an attempt of suicide and presented with desaturation and tachypnea. Lab findings were compatible with methemoglobinemia. After two days of treatment with ascorbic acid and activated charcoal, we observed the disappearance of desaturation and tachypnea. Methemoglobinemia can be treated with ascorbic acid and activated charcoal in limited resource settings.

The present article reports the synthesis of soluble, propyl‐substituted aromatic ring telechelic polycondensation blocks having molecular weights ranging from 1800 to 6500 g mol−1 and polymolecularities of 1.3 to 1.7. Chain‐growth polycondensation is performed, and the initiator is selected through reactivity studies, using 19F nuclear magnetic resonance (NMR) measurements. Gel permeation chromatography, NMR spectroscopy, and matrix‐assisted laser desorption/ionization time of flight mass spectrometry show that blocks are terminated by a methoxy group at one end and a fluorine atom at the other. Polymers are crystalline as synthesized, as shown by X‐ray diffraction and differential scanning calorimetry, do not recrystallize once melted, and undergo solvent‐induced crystallization. Crystalline peak positions and relative intensities are different from those observed for other poly(ether ketones). The difference in crystal form is proposed to stem from packing disruption related to the presence of propyl substituents. Thermogravimetry shows a good thermal resistance up to 450 °C.

The use of modern graphenic materials for improving oxygen barriers in food packaging and anti-corrosion barriers in coatings is explored by compounding and casting graphene nanoplatelets (GNP) with polyethylene (PE) and epoxy (EP). The GNP / PE films show comparable oxygen transmission rates to the neat PE films, indicating that further processing will be necessary to realize the desired enhancements. Early corrosion tests indicate that the GNP / EP coatings are providing more protection than the neat EP coatings on steel. Experiments to expand on these results are underway.