Assessment of the Structure and Properties of Water-Soluble Xanthan-graft-Polyacrylamide Copolymer by Optical Methods

Abstract

Optical methods play a key role in exploring the structure and properties of new polymeric materials. In this work, a set of optical techniques was used to characterize samples of a water-soluble xanthan-graft-polyacrylamide copolymer with varying side-chain lengths.
Infrared spectroscopy of our samples has revealed characteristic signals of both polymer types, namely: a broad peak within 1500–1700 cm−1 (carbonyl groups of polyacrylamide) and a band at 1400 cm−1 (C–N bond of the amide fragment, corresponding to deformation vibrations of COOH groups in xanthan), confirming the successful synthesis of the graft copolymer. Scanning electron microscopy (SEM) has shown a highly developed surface morphology with pore sizes ranging from 1 to 30 µm, with the predominant fraction of 1–4 µm. Dynamic light scattering (DLS) combined with SEM demonstrated that the graft copolymer macromolecules form spherical nanoparticles with an average diameter of 10–50 nm when dissolved in an aqueous medium, as well as their aggregates (500–1500 nm). Nanoparticles predominate in the dispersed phase, accounting for over 99% of the total particle fraction. The diffusion coefficient and zeta potential of the particles increase with a higher polyacrylamide content in the copolymer, while the electrical conductivity of the system decreases. Given the formation of nanoparticles, it is suggested that the xanthan-graft-polyacrylamide copolymer holds promise for the development of sensor materials.

Speaker

Anton Smirnov
Saratov State University, Saratov, Russian Federation
Russia

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