Concurrent ring-opening and atom transfer radical polymerization for synthesis of block copolymers, and their comprehensive chromatographic characterization

Gold nanoparticle-based selective and efficient spectrophotometric assay for the insecticide methamidophos

A reliable, rapid, and inexpensive nano-sized chemosensor is presented for methamidophos (MET) - an insecticide. Poly(lactic acid) (PLA)-stabilized gold nanoparticles (AuNPs) were synthesized by a simple one-pot, two-phase chemical reduction method. The synthesized PLA-AuNPs were subsequently employed for selective, efficient, and quantitative detection of MET. MET is one of the highly toxic pesticides used for eradication of agricultural and urban insects. Upon the addition of MET, the wine-red color of PLA-AuNPs swiftly transformed into greyish-blue, further corroborated by a significant bathochromic and hyperchromic shift in the SPR band. The presence of other interfering insecticides, metal salts, and drugs did not have any pronounced effect on quantitative MET detection. The detection limit, the quantification limit, and linear dynamic range of MET utilizing PLA-AuNPs were  0.0027 µM, 0.005 µM, and 0.005-1000 µM, respectively. The PLA-AuNP-based assay renders an efficient, rapid, accurate, and selective quantification of MET in food, biological, and environmental samples. The proposed sensor provides an appropriate platform for fast and on-the-spot determination of MET without requiring a well-equipped lab setup.

Novel epoxy-terminated macromonomers and their polymerization for synthesis of bottle-brush type amphiphilic block copolymers

Architecture of polymers has vital implications for their physical properties and applications. In this study, synthesis of a series of novel epoxy-terminated macromonomers namely Ep-DEGMME, Ep-TEGMME, Ep-EGMEE, Ep-EGMBE, and Ep-EGMHE is reported. The synthesized macromonomers vary in number of ethylene oxide units and length of the alkyl group. These macromonomers are first homopolymerized by anionic ring-opening polymerization for synthesis of homopolymers of a molar mass range. Subsequently, these macromonomers with different lengths of two segments (alkyl group and ethylene oxide units) are copolymerized with other monomers for synthesis of bottle-brush type architectures. In the first case, di- and tri-block copolymers of Ep-EGMBE are synthesized while using MeO-PEG or PEG as a macroinitiator; the resulting block copolymers have hydrophilic handle and hydrophobic brush. On the same lines, block copolymers of Ep-TEGMME with ε-caprolactone have hydrophobic handle and hydrophilic brush. The synthesized block copolymers are comprehensively characterized by SEC and liquid chromatography at critical conditions. The analysis reveals the successful synthesis of block copolymers while providing information on relative total molar mass, and individual block lengths of the block copolymers, along with amount of unwanted homopolymers in the sample.

Organocatalytic orthogonal ATRP and ring-opening polymerization using a single dual-function photocatalyst

Organocatalytic orthogonal atom transfer radical polymerization and ring-opening polymerization have been achieved using a single designer dual-function photocatalyst.