Preparation of Guanidine Polymer and Its Complex as Dual-Functional Agent for Cellulose Fibre-Based Hygiene Products

In this work, guanidine polymer was synthesized via a two-step polymerization, followed by forming complexes with chitosan in an attempt to improve antimicrobial performance and wet-strength of paper simultaneously. Structure and MW of the guanidine polymer were characterized using FTIR and GPC. It was found that the monomer ratios and the sequence of addition were the main influencing factors to determine the wet strength enhancement and antimicrobial activity of the resulting polymer. Adipic acid was proved to be difficult to react with guanidine salt in the condensation, therefore adipic acid and diethylenetriamine reacted prior to the other two monomers being added. Guanidino groups possessed higher antimicrobial activity when connected directly to the hexamethylendiamine. The resulting antimicrobial polymers were then mixed with chitosan to form the complexes, in which, chitosan acted as carriers for antimicrobial polymers and promoter for forming fibre-polymer networks. As a result, the significant synergy on improving both wet-strength and antimicrobial activities of handsheets was achieved, thus leading to promising cellulose fibre-based hygiene products. The antimicrobial activity of the guanidine polymer was characterized by determining MIC values and a shaking-flask method. To reveal the antimicrobial mechanism, cells of E. coli treated by the guanidine polymer were observed with AFM and ESEM.