A pixelated portrait of Antoine de Lavoisier was stored in a digitally-encoded poly(phosphodiester). The storage capacity attained in this work (440 bits/chain) is the highest ever reported for a synthetic informational polymer. To reach this very high capacity, a combination of data compression and polymer design was used. For instance, the digital polymer was synthesized by automated phosphoramidite chemistry using an optimized set of nineteen building blocks (8 coded monomers, 10 mass tags and one alkoxyamine linker enabling decryption by tandem mass spectrometry). Consequently, the polymer could be comprehensively decoded by electrospray mass spectrometry and the portrait of the French chemist was recovered.
22 September 2020 in Angewandte Chemie International Edition
A library of phosphoramidite monomers containing a main‐chain cleavable alkoxyamine and a side‐chain substituent of variable molar mass (i.e. mass tag) was prepared in this work. These monomers can be used in automated solid‐phase phosphoramidite chemistry and therefore incorporated periodically as spacers inside digitally‐encoded poly(phosphodiester) chains. Consequently, the formed polymers contain tagged cleavable sites that guide their fragmentation in mass spectrometry sequencing and enhance their digital readability. The spacers were all prepared via a seven steps synthetic procedure. They were afterwards tested for the synthesis and sequencing of model digital polymers. Uniform digitally‐encoded polymers were obtained as major species in all cases, even though some minor defects were sometimes detected. Furthermore, the polymers were decoded in pseudo‐MS3 conditions, thus confirming the reliability and versatility of the spacers library.
Short flax fibers have been modified by radiation-induced grafting using methacrylate monomers containing phosphorus to give them a flame-retardant character. Two methodologies, namely pre-irradiation and simultaneous irradiation grafting, were examined. Certain parameters, notably the dose and the irradiation source (e-Beam and γ rays), were evaluated. The grafting efficiency, in terms of phosphorus content (mass percentage), was measured by X-ray fluorescence spectrometry (XRF). Using simultaneous irradiation, 2.39 wt% phosphorus could be obtained from 10 kGy, compared to 100 kGy in pre-irradiation. Furthermore, for similar phosphorus levels, the location of the grafted polymer chains was different for the two methodologies. The effect of phosphorus content on thermal properties and fire behavior was evaluated on a microscopic scale using a pyrolytic flow combustion calorimeter (PCFC) and on a laboratory scale using a cone calorimeter. It was then pointed out that flammability was linked to the phosphorus content and likely its location, which is associated with the radiation-induced grafting methodology, showing that the grafting conditions influence the final fire properties. Simultaneous irradiation, thus, proved to be more interesting in terms of efficiency and final properties.
24 May 2020 in Macromolecular Rapid Communications