Mechanism for formation of porcine blood hydrogels used as additives in the mortar of traditional Chinese architectural painting

Abstract

Ancient Chinese architecture drawing is a unique form of ancient Chinese art. Porcine blood hydrogels are distinctive ingredients used to prepare the composite material of the substrate layer for architecture drawing. This investigation was focused on the mechanism for porcine blood hydrogel formation. Based on the traditional Chinese recipe for the preparation of porcine blood-lime mortar, samples with different ratios of porcine blood and lime water were prepared, and the molecular-scale interactions between the lime water and proteins in the porcine blood were examined with FTIR spectroscopy, Raman spectroscopy, XRD, XPS, fluorescence spectroscopy, contact angle and rheology studies. The mechanical properties and morphological features of the samples were detected with a rheometer, universal material testing machine and SEM. The results indicated that an appropriate amount of lime water was required for gelation of the porcine blood. With the appropriate alkalinity, sufficient carboxyl groups on the fibrin chains were deprotonated, and coordination with Ca²⁺ ions formed enough cross-links for support networks within the structure of the porcine blood hydrogel. Complexation of deprotonated carboxyl groups on the fibrin chains with Ca²⁺ ions led to the formation of a hydrophobic surface due alterations of the fibrin conformation and increased the adhesive properties of the hydrogel. With the hydrogel used as an ingredient in the preparation of a substrate layer composite, it is suggested that the hydrophobic surface of the hydrogel facilitated mixing with hydrophobic tung oil during preparation of the composite material, and strong adhesion of the hydrogel increased the mechanical strength and crack resistance of the substrate layer.