Along with the continuously advanced requirements for high performance rubbers such as in aircraft tires, natural rubbers show limitations in achieving high temperature creep resistance and high mechanical strength simultaneously. Meanwhile, the bi-terminal interactions of natural rubber (NR) exhibit unique reinforcement effects, which are difficult to realize in synthetic rubbers. In this article, four different types of bi-terminal polyisoprenes with distinct groups were synthesized, and they were assembled with penta-alanine molecule (5 A) to obtain high-performance rubbers by terminal hydrogen bonding reinforcement. Infrared tests indicate that the strong hydrogen bonds can be formed between two terminals and turn stronger after adding 5 A. Thus, the network of rubbers remains stable under different strains and temperatures and the activation energy of networks is elevated. As a result, this biomimetic design endows polyisoprene with high tensile strength compared with Malaysian NR and greater creep resistance. Further Mooney fitting and DMA test suggests that these confined hydrogen bonds not only increased the number of crosslinking points and entanglements of network, but also are beneficial for the segmental chain motion. In contrast to our common sense on hydrogen bonds which present large relaxation and hysteresis, this study proposes a facile method for preparing high-temperature creep-resistant rubbers by introducing confined hydrogen bonds, which represents a great advance in the structural biomimicry of NR.

中文翻译：

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双端基与五丙氨酸组装体间多重氢键对聚异戊二烯橡胶抗蠕变性能和机械强度的增强作用

随着对飞机轮胎等高性能橡胶的要求不断提高，天然橡胶在同时实现高温抗蠕变性和高机械强度方面表现出局限性。同时，天然橡胶（NR）的双端相互作用表现出独特的补强效果，这是合成橡胶难以实现的。本文合成了四种不同类型的具有不同基团的双端聚异戊二烯，并将其与五丙氨酸分子（5A）组装，通过端氢键补强获得高性能橡胶。红外测试表明，两个末端之间可以形成强氢键，并且在添加5A后变得更强。因此，橡胶网络在不同应变和温度下保持稳定，并且网络的活化能升高。因此，与马来西亚天然橡胶相比，这种仿生设计赋予聚异戊二烯更高的拉伸强度和更高的抗蠕变性。进一步的门尼拟合和DMA测试表明，这些受限氢键不仅增加了交联点和网络缠结的数量，而且有利于链段运动。与我们对氢键表现出较大松弛和滞后的常识相反，本研究提出了一种通过引入受限氢键来制备高温抗蠕变橡胶的简便方法，这代表了天然橡胶结构仿生学的巨大进步。