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1. Iodine-mediated photoATRP in aqueous media with oxygen tolerance

   https://doi.org/10.1039/C9PY01650C  

   Dadashi-Silab, Sajjad; Szczepaniak, Grzegorz; Lathwal, Sushil; Matyjaszewski, Krzysztof (January 2020, Polymer Chemistry)

   Water is an environmentally friendly medium for conducting reversible deactivation radical polymerizations. In this paper, we report the investigation of iodine-mediated photocontrolled atom transfer radical polymerization (photoATRP) in aqueous media. The iodine-based initiator was generated by an in situ halogen exchange from a commercially available bromine-based initiator, ethyl α-bromophenylacetate, using different iodide salts. Fast and well-controlled polymerization of a water-soluble methacrylate monomer was achieved in water under visible light irradiation, including blue, green and yellow lights. The nature of the reaction medium greatly affected the kinetics and control over the growth of polymers. Polymerizations in water resulted in a well-controlled reaction that provided high monomer conversion and polymers with low dispersities, whereas control over the polymerization was poor in bulk or in an organic solvent, N , N -dimethylformamide. Polymerizations were performed over a wide range of visible light in the absence of any photocatalyst. The selection of water as a reaction medium enabled use of iodide salts without the need for solubilizing agents. Moreover, iodine-mediated photoATRP was successfully performed in the presence of residual oxygen, signifying the potential of this polymerization system to tolerate oxygen without performing deoxygenation processes. 

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2. Polymers and Solvents Used in Membrane Fabrication: A Review Focusing on Sustainable Membrane Development

   https://doi.org/10.3390/membranes11050309  

   Dong, Xiaobo; Lu, David; Harris, Tequila A.; Escobar, Isabel C. (May 2021, Membranes)

   null (Ed.)

   (1) Different methods have been applied to fabricate polymeric membranes with non-solvent induced phase separation (NIPS) being one of the mostly widely used. In NIPS, a solvent or solvent blend is required to dissolve a polymer or polymer blend. N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and other petroleum-derived solvents are commonly used to dissolve some petroleum-based polymers. However, these components may have negative impacts on the environment and human health. Therefore, using greener and less toxic components is of great interest for increasing membrane fabrication sustainability. The chemical structure of membranes is not affected by the use of different solvents, polymers, or by the differences in fabrication scale. On the other hand, membrane pore structures and surface roughness can change due to differences in diffusion rates associated with different solvents/co-solvents diffusing into the non-solvent and with differences in evaporation time. (2) Therefore, in this review, solvents and polymers involved in the manufacturing process of membranes are proposed to be replaced by greener/less toxic alternatives. The methods and feasibility of scaling up green polymeric membrane manufacturing are also examined. 

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3. Torsional influences on cross‐conjugated thieno[3,4‐ b ]thiophene photochromes

   https://doi.org/10.1002/poc.4650  

   Adams, Nicholas P; Tovar, John D (January 2025, Journal of Physical Organic Chemistry)

   Abstract Photoresponsive conjugated polymers are a promising target for modern organic electronics. Numerous photoswitchable repeat units have been included covalently within polymeric structures to enable responsive chromic materials, most commonly through side‐chain appendages or through formal conjugation along a π‐conjugated backbone. We recently disclosed a new design whereby the photoswitch elements are cross conjugated to a conjugated polymer main chain. In this case, we found that the extent of photoconversion was dictated in part by competitive main chain light absorption, which could be suppressed by using a photoswitching motif that carried most of the frontier molecular orbital densities. Here, we report the modeling and synthesis of a series of thieno[3,4‐b]thiophene (TT)‐based photochromes with various aromatic flankers imparting varying degrees of steric bulk and π‐conjugation in order to elucidate the balancing act between steric and electronic factors to promote photochromism. These model systems provide a better understanding of the behavior of photochromic units within extended oligomeric and polymeric π‐conjugated materials. 

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4. S _N Ar Reaction Toward the Synthesis of Fluorinated Quinolino[2,3,4‐at]porphyrins

   https://doi.org/10.1002/ejoc.202001347  

   Thuita, Damaris; Guberman‐Pfeffer, Matthew_J; Brückner, Christian (December 2020, European Journal of Organic Chemistry)

   Abstract An intramolecular S_NAr displacement of oneo‐fluorine atom of ameso‐pentafluorophenyl‐substituted porphyrin metal complex by a neighboring β‐amino functionality generated the correspondingmeso‐fluorophenyl‐substituted metallo‐quinolino[2,3,4‐at]porphyrins that are not accessible using established quinoline‐annulation methodologies. The Cu(II), Ni(II), and Zn(II) complexes were thus prepared. The parent free base quinolino[2,3,4‐at]porphyrin is accessible only by demetallation of the copper or zinc complexes. A strong through‐space NMR‐spectroscopic coupling between the remainingo‐fluorine atoms on the annulatedmeso‐aryl group and the β‐hydrogen atom on the adjacent pyrrole moiety provide a clear spectroscopic signature for the annulation. Quinoline‐annulation alters the optical properties significantly. On account of the presence of the β‐amino functionality, all quinoline‐annulated porphyrins show strong halochromic responses with Brønsted acids and bases, the prerequisite for their potential use in chemosensing applications. 

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5. Facile Synthesis of Multifunctional Bioreducible Polymers for mRNA Delivery

   https://doi.org/10.1002/chem.202203393  

   Hickey, James_C; Hurst, Paul_J; Patterson, Joseph_P; Guan, Zhibin (January 2023, Chemistry – A European Journal)

   Abstract Bioreducible polymeric mRNA carriers are an emerging family of vectors for gene delivery and vaccine development. A few bioreducible systems have been generated through aqueous‐phase ring‐opening polymerization of lipoic acid derivatives, however this methodology limits hydrophobic group incorporation and functionality into resulting polymers. Herein, a poly(active ester)disulfide polymer is synthesized that can undergo facile aminolysis with amine‐containing substrates under stoichiometric control and mild reaction conditions to yield a library of multifunctional polydisulfide polymers. Functionalized polydisulfide polymer species form stable mRNA‐polymer nanoparticles for intracellular delivery of mRNAsin vitro. Alkyl‐functionalized polydisulfide‐RNA nanoparticles demonstrate rapid cellular uptake and excellent biodegradability when delivering EGFP and OVA mRNAs to cellsin vitro. This streamlined polydisulfide synthesis provides a new facile methodology for accessing multifunctional bioreducible polymers as biomaterials for RNA delivery and other applications. 

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