Synthesis and characterization of poly (acrylonitrile-g-lignin) by semi-batch solution polymerization and evaluation of their potential application as carbon materials

Understanding the factors that govern the graft polymer structure is of central importance to the development of technologies for converting polymers into carbon materials. In this work, poly (acrylonitrile-g-lignin) was synthesized by one-pot semi-batch solution polymerization of acrylonitrile (AN) with different amounts of Kraft lignin (KL), aiming the carbon materials producing. The synthesis process parameters to obtain poly (acrylonitrile-g-lignin) hybrid polymers from different KL contents were optimized. The purpose of this work was to substitute part of the AN by KL, with the KL amount varying from 0 to 35 wt.% in the copolymer and to investigate the consequent effects on the grafting percent, viscosity, overall monomer conversion, molar masses, thermal properties and carbon yield. The results obtained show the success in preparation of the grafted polymers with KL and that this insertion improved the thermal stability of the polymers and the carbon yield. The molar masses of poly (AN-g-KL) showed direct relationship with the amount of KL used and the grafting percentage. The results showed that the grafting percentage and viscosity of solutions decreases as the concentration of KL increased. The molar mass results and thermal properties showed a direct relationship to the KL concentration in the synthesized copolymer. Among the proportions of AN/KL studied, the copolymer 75/25 (P-25KL) presented the most promising results for application as carbon material precursor.