Design of a self-healing cross-linked polyurea with dynamic cross-links based on disulfide bonds and hydrogen bonding
Design of a self-healing cross-linked polyurea with dynamic cross-links based on disulfide bonds and hydrogen bonding
复制标题
基于二硫键和氢键的动态交联自修复交联聚脲的设计
DOI：
10.1016/j.eurpolymj.2018.08.005
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发表时间：
2018-10-01
影响因子：
6
通讯作者：
Guo, Bao-Hua
中科院分区：
文献类型：
--
作者：
Li, Ting;Xie, Zhining;Guo, Bao-Hua
在这项工作中，含有二硫键的二胺扩链剂与三异氰酸酯反应，产生基于可交换二硫键的动态化学交联。具有动态结合的聚脲体系在高于150 ℃时显示出储能模量的急剧下降和非常短的弛豫时间，使得该聚合物表现出典型的动态性能，例如自修复、再循环和滞后回线恢复。二硫键的引入主导了热刺激动力学性质，因为没有二硫键的对照样品即使在高温下也具有更长的弛豫时间。有趣的是，二硫键的存在导致氢键强度的下降，这可能导致它们更容易解离，随后更容易进行拓扑网络重排。此外，温度依赖的傅里叶变换红外光谱（FTIR）分析表明，氢键的可逆性几乎完全，揭示了氢键对材料动力学性能的重要影响。因此，氢键解离是导致动力学性质的间接原因，而二硫键的交换反应是主要原因。这些结果加深了我们对氢键在动态材料中作用的理解。此外，可获得的商业原料组分、操作可行性和简单性构成了如此制备的动态聚脲体系的巨大优点，即，实现工业应用和回收不可生物降解的交联聚脲的有效步骤。
In this work, diamine chain extenders containing disulfide bonds are reacted with triisocyanates to yield dynamic chemical cross-links based on exchangeable disulfide bonds. The polyurea system with dynamic bonding shows drastic decline of storage modulus and very short relaxation times above 150 degrees C so that this polymer exhibits typical dynamic properties, e.g. self-healing, recycling and hysteresis loop recovery. The introduction of disulfide bonds dominates the thermal stimulated dynamic properties, since the control samples without disulfide bonds have longer relaxation times even at high temperatures. Interestingly, presence of disulfide bonds leads to the decline of hydrogen bonding strength which can result in their easier dissociation and subsequently easier topological network rearrangement. In addition, almost complete reversibility of the hydrogen bonding is observed from temperature-dependent Fourier Transform Infrared Spectroscopy, which reveals the important influence of hydrogen bonding on dynamic properties. Thus, Hydrogen bonding dissociation is an indirect reason of dynamic properties, while exchange reaction of disulfide bonds is the primary cause. The results may deepen our understanding of the role of hydrogen bonding in the dynamic materials. In addition, the available commercial raw component, operational feasibility and simplicity constitute a great advantage of the so-prepared dynamic polyurea system, i.e. an effective step to implementation of industrial applications and recycle the nonbiodegradable crosslinked polyureas.