Metal-free visible-light photocatalysts offer a clean, sustainable solution to many pressing environmental issues. Herein, we present a molecular design strategy to fine-tune the valence and conduction band levels of a series of conjugated microporous polymer networks based on poly(benzochalcogenadiazole) for heterogeneous photocatalysis. Enhanced photocatalytic efficiency was observed by altering the chalcogene moieties in the electron-accepting benzochalcogenadiazole unit of the polymer backbone structure. Photooxidative coupling of benzylamines was chosen as a model reaction. This design strategy leading to enhanced efficiency could potentially improve a wide range of photoredox reactions.

Dimethacrylate or divinyl-functionalized acetal-based crosslinkers were synthesized as building elements of acid-sensitive crosslinked hydrogels. Each crosslinker was prepared under catalytic acidic conditions with different functional groups installed at the acetal position. The hydrophilicity of the crosslinkers was tuned to control acidic-hydrolysis rate. We report the synthesis of hydroxyethyl dimethacrylatefunctionalized dimethyl ketal (CL1), meta-or para-methoxybenzaldehyde based acetals (CL2m and CL2p), poly(ethylene glycol) dimethacrylate-functionalized dimethyl ketal-based crosslinker (CL3), and divinyl-functionalized meta-methoxybenzaldehyde-based acetal crosslinker (V-CL2m). An examination of acetal hydrolysis kinetics of the monomers was performed in aqueous buffer solutions using 1 H NMR (proton nuclear magnetic resonance) and UV-Vis (ultraviolet-visible) spectroscopy at various pH ranges.The hydrolysis rates were strongly dependent on the structure of the acetal. Network films containing CL2m were prepared by thermally initiated polymerization with either hydroxyethylmethacrylate (HEMA) or methylmethacrylate (MMA). A study of the hydrolysis kinetics of these crosslinked films was performed using GC-MS (gas chromatography and mass spectroscopy) to understand the effect of monomer hydrophilicity, crosslinking density, and polymerization mechanism at different pHs. The crosslinked films composed of the hydrophilic monomer, HEMA, show faster hydrolysis than those containing more hydrophobic monomers (e.g. MMA). The hydrolysis rate decreases as the crosslinking density increases. In the case of thiol-ene networks formed by reacting pentaerythritol tetrakis(3mercaptopropionate) and V-CL2m, each repeating unit is composed of an acid-degradable acetal-moiety.Hydrolysis of the thio-ene network films results in depolymerization into two lower molecular weight components, pentaerythritol tetrakis(3-(6-hydroxyhexylthio)propanoate) and meta-methoxybenzaldehyde.

A new phosphorylated ethylamine salt was synthesized that releases the free amine in situ under water‐free conditions. This storable precursor molecule was used to synthesize a mono‐substituted cyanuric chloride. Further substitutions could not be performed due to the low reactivity of this cyanuric chloride derivative. Also, two novel, bridged phosphonamidates were prepared. Owing to the P‐N synergy, they show enlarged char yields and therefore are promising flame retardants.

A new organophosphorus, zinc‐containing polyacrylate is synthesized that has potential use as flame retardant for polyamides. To achieve this goal, the Phospha‐Michael addition is utilized to selectively add 9,10‐dihydro‐9‐oxa‐10‐phospha‐phenanthrene‐10‐oxide (DOPO) to one acrylate group of zinc acrylate followed up by radical polymerization of the remaining acrylate group in a one‐pot approach. To verify the effectiveness of the synthesis method, it is compared to a second two‐step approach via diethyl zinc. In order to investigate the influence of molecular weight as well as phosphorus content on the flame retardant properties, the small‐molecule complex zinc bis(3‐(6‐oxidodibenzo[c,e][1,2]oxaphosphinin‐6‐yl)propionate) and the nonphosphorus thermoset poly(zinc diacrylate) are synthesized as well. All three substances are investigated as flame retardants for pure and glass‐fiber (GF) reinforced polyamide 6 (PA 6) and 66 (PA 66) in different compounds with and without melamine polyphosphate (MPP). Most of the samples show excessive dripping in the vertical burning test UL‐94 V. However, V‐1 classification is achieved in GF‐reinforced PA 66 with the DOPO‐ and zinc‐containing polyacrylate in combination with MPP. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47586.

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