Feng Zhanbin, Hu Jing, Zuo Hongli, Ning Nanying, Zhang Liqun, Yu Bing, Tian Ming
ACS Appl Mater Interfaces. 2019 Jan 9;11(1):1469-1479. doi: 10.1021/acsami.8b18002. Epub 2018 Dec 28.
Photothermal-induced self-healable and shape memory materials have drawn much attention due to the rapidly growing technical applications and environmental requirements. As epoxy natural rubber (ENR) is a kind of bio-based elastomer with good mechanical properties, weather resistance, and air impermeability, it is of great significance to incorporate ENR with recyclable, photothermal-induced self-healable and shape memory properties. In this study, we report a simple method to cross-link ENR with dodecanedioic acids (DAs) through esterification reaction, and during the cross-linking process, a little aniline trimer (ACAT, a kind of oligoaniline) was added at the same time. Then, the ENR-DA-ACAT vitrimers that were covalently cross-linked with recyclable, self-healable, and multiple responsive properties were obtained, which also possessed various functions. As a result of the transesterification reactions at elevated temperatures, the ENR-based vitrimers possess the ability to be reprocessed and self-healed, and the mechanical properties could be maintained even after three consecutive breaking/mold pressing cycles. Besides, the vitrimer is also responsive to near-infrared (NIR) light and pH with the introduction of ACAT, and we also find that ACAT can be used as a catalyst to accelerate the transesterification reaction. Moreover, it is demonstrated that the ENR-DA-ACAT vitrimer could also be used to construct the reconfigurable shape memory polymer; the shape fixing ratio and shape recovery ratio are both above 95% in the reconfiguration process, and the multistage shape memory performance can also be achieved by NIR irradiation, which will potentially lead to a wide application for ENR in the field of actuators.
由于技术应用的快速增长和环境要求，光热诱导的自修复和形状记忆材料受到了广泛关注。环氧天然橡胶（ENR）是一种具有良好机械性能、耐候性和不透气性的生物基弹性体，将其与具有可回收、光热诱导自修复和形状记忆特性相结合具有重要意义。在本研究中，我们报道了一种通过酯化反应将ENR与十二烷二酸（DAs）交联的简单方法，并且在交联过程中，同时加入少量苯胺三聚体（ACAT，一种低聚苯胺）。然后，获得了具有可回收、自修复和多重响应特性的共价交联的ENR-DA-ACAT Vitrimer，其还具有多种功能。由于高温下的酯交换反应，基于ENR的Vitrimer具有再加工和自修复的能力，即使经过三个连续的断裂/模压循环后，机械性能仍能保持。此外，由于ACAT的引入，Vitrimer对近红外（NIR）光和pH也有响应，并且我们还发现ACAT可以用作催化剂来加速酯交换反应。此外，证明了ENR-DA-ACAT Vitrimer还可用于构建可重构形状记忆聚合物；在重构过程中，形状固定率和形状恢复率均高于95%，并且通过近红外辐射还可实现多级形状记忆性能，这将有望使ENR在致动器领域得到广泛应用。
