Marine plastic pollution is a worldwide challenge making advances in the field of biodegradable polymer materials necessary. Polylactide (PLA) is a promising biodegradable polymer used in various applications; however, it has a very slow seawater degradability. Herein, we present the first library of PLA derivatives with incorporated “breaking points” to vary the speed of degradation in artificial seawater from years to weeks. Inspired by the fast hydrolysis of ribonucleic acid (RNA) by intramolecular transesterification, we installed phosphoester breaking points with similar hydroxyethoxy side groups into the PLA backbone to accelerate chain scission. Sequence-controlled anionic ring-opening copolymerization of lactide and a cyclic phosphate allowed PLA to be prepared with controlled distances of the breaking points along the backbone. This general concept could be translated to other slowly degrading polymers and thereby be able to prevent additional marine pollution in the future.
Cellulose acetate is one of the most important cellulose derivatives and commercially mainly produced using the Acetic Acid Process, in which overstoichiometric amounts of acetic anhydride and concentrated acetic acid...
New sustainable concepts have to be developed to overcome the increasing problems of resource availability. Cellulose derivatives with tunable material properties are promising biobased alternatives to existing petroleum-derived polymeric materials. However, the chemical modification of cellulose is very challenging, often requiring harsh conditions and complex solubilization or activation steps. More sustainable procedures toward novel cellulose derivatives are therefore of great interest. Herein, we describe a novel concept combining two approaches, (i) tandem catalysis and (ii) cellulose derivatization, by applying a single catalyst for three transformations in the DMSO/DBU/CO2 switchable solvent system. Cellulose was functionalized with four different biobased isothiocyanates, which were formed in situ via a catalytic sulfurization of isocyanides with elemental sulfur, preventing the exposure and handling of the isothiocyanates. The degree of substitution of the formed O-cellulose thiocarbamates was shown to be controllable in a range of 0.52–2.16 by varying the equivalents of the reactants. All obtained products were analyzed by ATR-IR, 1H, 13C, and 31P NMR spectroscopy as well as size exclusion chromatography, elemental analysis, differential scanning calorimetry, and thermal gravimetric analysis. Finally, the tandem reaction approach was shown to be beneficial in terms of efficiency as well as sustainability compared to a stepwise synthesis. Recycling ratios ranging from 79.1% to 95.6% were obtained for the employed components, resulting in an E-factor of 2.95 for the overall process.
For the transition toward a safer and more sustainable production of polymeric materials, new synthetic concepts need to be developed. Herein, we describe a catalytic, solvent-free synthesis approach for novel thionourethane thermoset materials, in which the diisothiocyanate reactant is generated in situ via a sulfurization of isocyanides with elemental sulfur, preventing the exposure and handling of the diisothiocyanate. In this one-pot procedure, castor oil fulfills a dual role: (i) acting as the solvent for the in situ diisothiocyanate synthesis in the first step and (ii) reacting as the polyol component in the subsequent thionourethane thermoset formation. The kinetics of the consecutive two steps were studied in detail via real-time IR measurements, and the thermoset crosslinking step was found to be thermally triggerable after the diisothiocyanate reactant is quantitatively formed, enabling high control over the curing process of the system. Differential scanning calorimetry, thermogravimetric analysis, and rheological measurements were performed to investigate the thermal and mechanical properties of the novel thionourethane thermosets and then compared to analogous polyurethane materials. Our results demonstrate an unprecedented approach for thermoset synthesis via an in situ reagent synthesis, i.e., the generation of isothiocyanates from isocyanides by catalytic activation of elemental sulfur, and subsequent thermally triggerable thermosetting with a polyol, resulting in materials with appealing properties.
Compound mixtures represent an alternative, additional approach to DNA and synthetic sequence-defined macromolecules in the field of non-conventional molecular data storage, which may be useful depending on the target application. Here, we report a fast and efficient method for information storage in molecular mixtures by the direct use of commercially available chemicals and thus, zero synthetic steps need to be performed. As a proof of principle, a binary coding language is used for encoding words in ASCII or black and white pixels of a bitmap. This way, we stored a 25 × 25-pixel QR code (625 bits) and a picture of the same size. Decoding of the written information is achieved via spectroscopic (1H NMR) or chromatographic (gas chromatography) analysis. In addition, for a faster and automated read-out of the data, we developed a decoding software, which also orders the data sets according to an internal “ordering” standard. Molecular keys or anticounterfeiting are possible areas of application for information-containing compound mixtures.
Carbon dioxide (CO2) is an easily available, renewable carbon source and can be utilized as a comonomer in the catalytic ring‐opening polymerization of epoxides to generate aliphatic polycarbonates. Dodecyl glycidyl ether (DDGE) is copolymerized with CO2 and propylene oxide (PO) to obtain aliphatic poly(dodecyl glycidyl ether carbonate) and poly(propylene carbonate‐co‐dodecyl glycidyl ether carbonate) copolymers, respectively. The polymerization proceeds at 30 °C and high CO2 pressure utilizing the established binary catalytic system (R,R)‐Co(salen)Cl/[PPN]Cl. The copolymers with varying DDGE:PO ratios are characterized via NMR, FT‐IR spectroscopy, and SEC, exhibiting high molecular weights between 11 400 and 37 900 g mol−1 with dispersities (Ð = M w/M n) in the range of 1.37–1.61. Copolymers with T gs of −11 °C or T ms from 5 to 15 °C and thermal decomposition >200 °C depending on the comonomer ratio, are obtained as determined by differential scanning calorimetry/TGA.
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