No abstract

Atom transfer radical polymerization (ATRP) of oligo(ethylene oxide) monomethyl ether methacrylate (OEOMA500) in water is enabled using CuBr2 with tris(2‐pyridylmethyl)amine (TPMA) as a ligand under blue or green‐light irradiation without requiring any additional reagent, such as a photo‐reductant, or the need for prior deoxygenation. Polymers with low dispersity (Đ = 1.18–1.25) are synthesized at high conversion (>95%) using TPMA from three different suppliers, while no polymerization occurred with TPMA is synthesized and purified in the laboratory. Based on spectroscopic studies, it is proposed that TPMA impurities (i.e., imine and nitrone dipyridine), which absorb blue and green light, can act as photosensitive co‐catalyst(s) in a light region where neither pure TPMA nor [(TPMA)CuBr]+ absorbs light.

Combining synthetic polymers with RNA paves the way for creating RNA-based materials with non-canonical functions. We have developed an acylation reagent that allows for direct incorporation of the atom transfer radical polymerization (ATRP) initiator into both short synthetic oligoribonucleotides and natural biomass RNA extracted from torula yeast. The acylation was performed in a quantitative yield. The resulting initiator-functionalized RNAs were used for grafting polymer chains from the RNA by photoinduced ATRP, resulting in RNA-polymer hybrids with narrow molecular weight distributions. The RNA initiator was used for the polymerization of oligo(ethylene oxide) methyl ether methacrylate, poly(ethylene glycol) dimethacrylate, and N-isopropylacrylamide monomers, resulting in RNA bottlebrushes, hydrogels, and stimuli-responsive materials. This approach, readily applicable to both post-synthetic and nature-derived RNA, can be used to engineer the properties of a variety of RNA-based macromolecular hybrids and assemblies providing access to a wide variety of RNA-polymer hybrids.

With the idea of improving the mechanical properties of acrylonitrile-butadiene rubber (NBR) for potential industrial application, hybrid nanofillers prepared by hybridizing graphene oxide (GO) with halloysite nanotubes (HNT), were incorporated through mechanical blending to reinforce NBR. Graphene oxide/halloysite nanotubes (GH) hybrid filler demonstrates significant synergetic reinforcement effect in mechanical properties of NBR. The substantial improvement in mechanical properties is attributed to the uniform dispersion of hybrid filler in the matrix and to the strong interaction between the hybrid filler and matrix. Scanning electron microscopy images obtained from the fractured surface of GH-reinforced NBR composites showed more uniform dispersion with less agglomerations and cracks than that of GO and HNT. The strong interaction between the hybrid filler and NBR was confirmed by the increase of glass transition temperature, storage modulus and crosslinking density.