Natural rubber (NR) consists of mainly cis-1,4-polyisoprene with proteins as notable nonrubber components that significantly influence its properties. A relatively unexplored aspect is the role of these proteins in reducing and stabilizing metal ions to form metallic particles. Here, the NR/ZnO composite is successfully prepared by in situ generation of ZnO in the NR latex for the first time. With the aid of the proteins, the amount of ZnO is slightly higher than that formed in the saponified NR latex (SPNR), where some proteins are removed. Importantly, the noncovalent bonds between the proteins and/or amino acids with the ZnO formed in the NR latex can provide the self-healing behavior of the NR/ZnO composite. However, heating at ≈40 °C is still necessary for reducing the healing time and increasing the self-healing efficiency of the composite. Nevertheless, greater noncovalent bonds within NR/ZnO hinder rubber molecular chain interdiffusion and rearrangement essential for self-healing behavior in uncross-linked rubber, resulting in lower healing efficiency compared to SPNR/ZnO. This study underscores the significance of proteins and/or amino acids on NR's properties, despite their minor presence. Without sophisticated NR modification, this is a very simple and low-cost technique to achieve the NR/ZnO composite with self-healing behavior.

中文翻译：

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蛋白质介导的氧化锌合成用于天然橡胶的自修复

天然橡胶 (NR) 主要由顺式-1,4-聚异戊二烯组成，蛋白质是显着影响其性能的显着非橡胶成分。一个相对未探索的方面是这些蛋白质在还原和稳定金属离子以形成金属颗粒方面的作用。在此，首次通过在天然橡胶乳胶中原位生成氧化锌成功地制备了天然橡胶/氧化锌复合材料。在蛋白质的帮助下，ZnO 的量略高于皂化 NR 乳胶 (SPNR) 中形成的量，其中一些蛋白质被去除。重要的是，蛋白质和/或氨基酸与 NR 乳胶中形成的 ZnO 之间的非共价键可以提供 NR/ZnO 复合材料的自修复行为。然而，为了减少愈合时间并提高复合材料的自修复效率，仍然需要在约40°C下加热。然而，NR/ZnO 中较大的非共价键阻碍了橡胶分子链的相互扩散和重排，这对于未交联橡胶的自修复行为至关重要，导致与 SPNR/ZnO 相比修复效率较低。这项研究强调了蛋白质和/或氨基酸对 NR 特性的重要性，尽管它们的存在量很少。无需复杂的 NR 改性，这是一种非常简单且低成本的技术，可以实现具有自修复行为的 NR/ZnO 复合材料。