Novel biodegradable polymers modified by humic acids

Abstract

The possibility of using humic acids (HA) as hybrid modifiers is considered. They were taken from lignite using first sodium pyrophosphate solution, then a 1 % solution of NaOH for extraction, and next mineral acid for precipitation. It has shown that in gelatin–HA hybrid systems, the latter mainly join water molecules and “sequester” them to prevent their interaction with gelatin chains. In the hydroxypropyl methylcellulose (HPMC)-HAs systems, the processes of polymer cross-linking through multipoint chelate interaction with the carboxylate group of HAs have been determined. Hybrid polyvinyl alcohol (PVA)-HAs structures are obtained by the matrix synthesis mechanism. Also, during the hybrid modification of PVA with HAs, additional supramolecular interactions, in addition to hydrogen bonds, occur between their functional groups as a result of crystallization. It was found that hybrid modification of HAs within the matrix synthesis of gelatin-based biopolymer hydrogels allows obtaining polymer hydrogels with an increased swelling degree and gives them antibacterial qualities. The optimal content of HAs in biodegradable polymers based on gelatin, PVA and HPMC is 10 % by mass.