Synthesis of carboxymethyl cellulose sodium salt and N-vinylimidazole graft copolymers and their aqueous solutions property researching
Purpose. The aim of this work is synthesis of carboxymethyl cellulose sodium salt (Na-CMC) and N-vinylimidazole (VI) graft copolymers and investigation of the properties of their water solutions. Methods and methodology. The Na-CMC-g-VI co-polymers with different content of VI were obtained by free radical polymerization with ox-red initiator system (Table 1). Selective precipitation and dialysis were used to remove unreacted Na-CMC, VI and other excess components. Results. The structure, compound and grafting efficiency (GE) of the synthesized co-polymers were determined by Fourier transmission infrared spectroscopy (Table 1). Polymerization kinetics for all samples is researched by co-polymer composition determination with UV spectroscopy use, and was found that it was ending during 180 minutes (Fig. 1) Molecular weights of grafted poly-N-vinylimidazole were calculated from gel permeation chromatography static light scattering data. It was found that GE value is maximal for co-polymer containing 43 % w of VI (Table 2). Dynamic light scattering (DLS) and transmission electron microscopy researching showed that particles of all synthesized co-polymers in water possess non-spherical form (Fig. 2), and their surfaces have negative values of zeta-potential (Table 3). The hydrodynamic radii of the polymer particles are in the range of 120-152 nm, and slightly increase with VI content growth. It was found by DLS that polymer particles of all co-polymers are stable in 0.15 M NaCl aqueous solution and in the wide pH range which allows to apply them as vectors for targeted drug delivery (Fig. 3, 4). Conclusion. To sum up, Na-CMC-g-VI co-polymers were prepared by free radical copolymerization with ox-red initiator system. Aqueous solutions of the synthesized co-polymers were characterized by dynamic light scattering, transmission electron microscopy and zeta-potential measurement.