Effect of Mussel-Inspired Polydopamine Functionalized Hydroxyapatite on the Properties of Natural Rubber Latex Films

Improving the strength and oxidation resistance of natural latex films and reducing the water-soluble protein content are essential for the preparation of high-quality multifunctional natural rubber latex (NRL) products. Hydroxyapatite (HA) has received much attention as a biocompatible material for its unique protein adsorption properties, but its poor compatibility with NRL has resulted in compromised results. Therefore, in this work, HA was modified by dopamine with excellent adhesion properties of -OH and -NH2-rich to improve the compatibility of HA with rubber matrix. Therefore, the present work utilizes the excellent adhesion property of dopamine (PDA) to adsorb onto the HA surface through pi-pi interactions. The HA was then functionalized to obtain modified HA (HA-PDA), which improves the compatibility between natural latex and HA, enhances the physical and mechanical properties, antioxidant properties, and reduces the water-soluble protein content of natural latex films. When 0.18 wt% HA-PDA was added, the tensile and tear strengths of the composite film increased by 32.4% and 42.92%, respectively, compared to the natural latex film. After 36 h of aging, the HA-PDA/NRL adhesive film still has 35.92% tensile strength retention compared to commercial antioxidant 246. Moreover, the water-soluble protein dissolved in HA-PDA/NRL vulcanized films was only 15.05 mu g/g, which was 67.49% lower than that of NRL. In addition, good biocompatibility of the composite adhesive film was also demonstrated by cytotoxicity experiments, which provides a new method for the preparation of high-strength, strong antioxidant, hypoallergenic, and good biocompatible latex products.