From biopolymer to archaeological protector: glycogen- g -polyacrylamide as a nano-consolidant for the reinforcement of fragile parchment manuscripts

Parchment manuscripts and documents stored in museums, libraries, and archives are prone to degradation due to exposure to fluctuating temperature and humidity, excessive light, etc., leading to their fragility and brittleness. This study focuses on the synthesis and assessment of glycogen grafted with polyacrylamide (glycogen-g-PAAm) as a novel nanomaterial for strengthening fragile parchment. New parchment samples were created, and accelerated heat aging was employed to simulate aged samples, which were then treated with varying concentrations of the grafted glycogen. A modified biomacromolecule nanomaterial based on natural polymer-glycogen grafted with polyacrylamide through solution polymerization as an environmentally friendly procedure was successfully synthesized in a good yield. The optimal factors for the nanomaterial synthesis reaction, including reaction temperature, polymerization and grafting reaction time, initiator concentration, and monomer concentration, were determined. Additionally, the conversion, solid content, and grafting percentages were calculated. The glycogen-g-PAAm nanomaterial was characterized using Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric (TG) analysis. The samples underwent analysis prior to and subsequent to accelerated thermal aging utilizing various techniques including SEM, mechanical properties measurement, color change measurement, contact angle measurement, and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR FTIR). The nanomaterial developed was found to be quasi-spherical with an average diameter of around 23 nm. The results of the analysis demonstrated the enhancement of the treated parchment's characteristics with glycogen-g-PAAm nanomaterial. Based on the findings, a concentration of 2% from the grafted glycogen is recommended for treating historical parchment manuscripts and documents.