Investigation on thermal, rheological, dielectric and spectroscopic properties of a polymer containing pendant spiroacetal moieties

Abstract

The synthesis of “smart” molecules is in current areas of research as their specific functions can significantly improve the performance in various applications. This study is devoted to the investigation of poly(N,N dimethylacrylamide-co-3, 9-divinyl-2, 4, 8, 10-tetraoxaspiro (5.5) undecane) as “smart” macromolecular compound in order to evaluate the physico-chemical characteristics in terms of molecular weight, temperature-sensitive abilities, thermal stability, as well as its rheological, dielectric and spectroscopic properties. Differential scanning calorimetry investigation on the studied copolymer indicated a single glass transition temperature, while the rheological studies (rotational tests) confirmed a non-Newtonian shear-thinning fluid behavior of the copolymer solution. Dielectric properties of the copolymer have been evaluated in order to investigate the relaxation processes. It was found that the main contribution to dielectric relaxation derived from the non-cooperative motion of the side groups. The thermosensitive character was evidenced by the modification of the hydrodynamic radius of the macromolecular chains particles, which were estimated by dynamic light scattering technique. The fluorescence spectroscopy confirmed the structure of the copolymer, the spiroacetal moiety getting an axial conformation which is more stable, has lower energy and is more capable of making specific interactions with solvents, phenomena underlined by different shapes of the emission spectra of the copolymer.