Water-soluble starlike poly(acrylic acid) graft polymer: preparation and application as templates for silver nanoclusters

Studies on Electrical, Thermal and Corrosion Behaviour of Cashew Tree Gum Grafted Poly(Acrylamide)

The present work aimed to study the thermal transitions, electrical properties and corrosion behaviour of cashew tree gum (CTG), poly (acrylamide) (PAM) and cashew tree gum grafted poly (acrylamide) (CTG-g-PAM) copolymer. Various amounts of acrylamide monomer were grafted onto cashew gum using a radical polymerization method. The formation of graft copolymer was analysed by FTIR, UV, SEM, DSC and electrical conductivity measurements. The FTIR and UV spectrum infers the occurrence of strong intermolecular interaction between cashew gum and poly (acrylamide). SEM photographs revealed that the acrylamide unit was well inserted into the cashew gum segments. The DSC analysis showed a significant decrease in glass transition temperature with an increase in amount of acrylamide chains. CTG shows higher AC conductivity than PAM and the conductivity of graft copolymer increases with the concentration of acrylamide up to certain concentration of monomer and thereafter the value decreases. The dielectric properties such as dielectric constant and dielectric loss tangent values of PAM was lower than CTG and the dielectric values also shows a similar trend as AC conductivity. CTG, PAM and its graft copolymer with various amount of poly (acrylamide) have been investigated as a corrosion inhibition for mild steel in hydrochloric acid. The inhibition efficiency increased with increase in concentration of PAM in the graft copolymer. PAM was found to have the high inhibition efficiency than CTG, due to the difference in their molecular structures. The corrosion rate of all the samples enhanced with the raise in temperature whereas the inhibition efficiency deceases.

The relationship between DNA sequences and oligonucleotide-templated silver nanoclusters and their fluorescence properties

A novel approach was developed to study the relationship between DNA sequences and DNA-templated silver nanoclusters (DNA-Ag NCs) in detail by using an ordinary DNA strand as an example. Three kinds of Ag NCs are formed by using the DNA strand as a scaffold. By dividing the DNA template into several parts according to their different affinities to Ag(+) , it was found that the fluorescence properties of DNA-Ag NCs are related to not only the sequences but also to the position of different parts in the template, which provides a more efficient approach to obtain DNA-Ag NCs with required photoluminescence properties and may ultimately contribute to the targeted synthesis of DNA-Ag NCs.