One-pot synthesis of PAMAM-grafted hyperbranched cellulose towards enhanced thermal stability and antibacterial activity

Abstract

Cellulose is widely used as a biomaterial because of its good biodegradability and biocompatibility. In this study, the periodate oxidation method was used to prepare dialdehyde cellulose (DAC), which was then modified with polyamidoamine dendrimer (PAMAM G0) by the hyperbranched crosslinking synthesis to obtain novel dialdehyde cellulose-based polymers (DPs) with high thermal stability and antibacterial activity. The characterization found that PAMAM was successfully grafted onto the cellulose backbone. Moreover, the thermal weight-loss temperature of DPs decreased, the char yields increased, and the crystallinity decreased significantly as the amount of PAMAM increased. The crystallinity was about 46.50%. Specifically, when the ratio of the aldehyde group in DAC to the amine group in PAMAM was 1:1, the maximum thermal-denaturation temperature and weight-loss temperature (Tmax) of the DPs reached 136 ℃ and 365.8 ℃, respectively. In addition, DPs showed a uniform long-strip structure with a good particle size distribution, preventing the self-assembly and aggregation of cellulose and DAC. Disk diffusion tests showed that the DPs had significant antibacterial activity against Escherichia coli and Staphylococcus aureus, with the inhibition zone diameters reaching 13–15 mm. Thus, DPs with good thermal stability and antibacterial activity could be used as a new type of cellulose-based functional material.