Characterization and applications of amino acid-bridged nano-Ag end-capped diblock copolymer

Abstract

Ring opening polymerization of ε-caprolactone and tetrahydrofuran was carried outunder inert atmosphere with the monomer-to-initiator ratio of 100 and treated with AgNO3 to form Ag nanoparticle-centered diblock copolymer. Amino acids such as alanine (Ala) and asparagine (Aspar) were used as a lone chemical initiator at 160 °C in the presence of stannous octoate as a catalyst. The resultant Ala- and Aspar-bridged diblock copolymer was characterized by Fourier-transform infrared (FTIR), 1H nuclear magnetic resonance spectra, differential scanning calorimetry, thermogravimetric analysis, field-emission scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), gel permeation chromatography (GPC) and circular dichroism spectroscopy techniques. The FTIR spectrum showed a peak corresponding to the tetrahydrofuranium ion and confirmed the diblock copolymer formation. The diblock copolymer formation was confirmed by an increase in Mw in the GPC analysis. The HRTEM showed the size of the Ag nanoparticles was less than 10 nm. The Ag end-capped diblock copolymers were tested for catalytic reduction of p-nitrophenol (NiP) and the apparent rate constant (kapp) for the reduction of NiP was calculated as 1.15 × 10–2 s−1 with the help of UV–Visible spectrophotometer. The Ag nanoparticle-centered diblock copolymer was tested for low-temperature splinting application. Mechanical properties of the polymers were also tested.