可逆“牺牲键”增韧橡胶的分子设计与原理研究

The toughness of rubbers is one of the critical factors that determine the ability of anti-crack growth, thus it is crucial to the service safety of high-tech devices and facilities such as high-speed train and space craft. However, unfilled rubbers generally possess poor toughness. In this project, we will use hydrogen bonds as reversible sacrificial bonds to dissipate energy and toughen rubbers. We will systematically design the topological structure of rubber matrix and sacrificial bonds, and the bond energy of sacrificial bonds. We will investigate the influence of the designed molecular structures on the structure and transition of the transient network. Based the network structure, we will develop a new constitutive model to separate the contributions of the viscoelasticity of rubber matrix and the viscoelasticity of reversible sacrificial bonds to the energy dissipation and mechanical properties of rubbers. This generates kinetic parameters of association and dissociation of reversible sacrificial bonds. With these parameters, we can understand the correlation between the molecular structure and the macro-scale mechanical properties. Finally, we will answer what is the best molecular design of reversible sacrificial bond toughened rubbers. The success of this project will not only reveal the toughening mechanism of reversible sacrificial bonds, but also generate a new series of high-toughness rubbers. This is of significant importance to the investigation of soft-matter physics and the development of high-performance rubbers from both theoretical and practical views.

橡胶韧性是决定橡胶材料抵抗裂纹扩展能力的关键因素，它关系到含有关键橡胶结构件的高速列车、航天飞机等的安全服役。针对未填充橡胶韧性不足的问题，拟采用氢键形成的可逆“牺牲键”耗散能量，增韧橡胶；系统地设计橡胶基体的拓扑结构，可逆“牺牲键”的拓扑结构和键能大小，研究这些结构因素对可逆“牺牲键”形成的瞬态网络结构和松弛转变特性的影响；基于可逆“牺牲键”增韧橡胶的网络结构特征，建立本构模型离析可逆“牺牲键”粘弹性和橡胶基体粘弹性对橡胶能量耗散和力学性能的贡献，理解分子尺度上可逆“牺牲键”络合和解络合的动力学过程与橡胶非线性粘弹性的关系；以非平衡态下可逆“牺牲键”的动力学参数为桥梁，建立橡胶结构与性能的关系，最终回答如何设计可逆“牺牲键”增韧橡胶的分子结构。本项目期待揭示可逆“牺牲键”增韧橡胶的原理，获得一类新型高韧性的橡胶，对软物质物理的研究具有重要的理论价值，对高性能橡胶的研发具有重要的实际意义。

针对未填充橡胶韧性低的问题，通过共聚或复合的方法在橡胶（或弹性体）中引入氢键、离子键、配位键、悬垂链缠结点、刚性骨架等作为可逆“牺牲键”，系统地调控可逆“牺牲键”的键能、含量和拓扑结构，及其在基体中的聚集态结构，制备了一系列高韧性和高强度的弹性体。借助升温红外光谱和核磁氢谱，揭示了可逆“牺牲键”的络合和解络合过程；采用热分析和粘弹特性分析，阐明了可逆“牺牲键”的键能、含量和拓扑结构对其松弛转变温度、松弛时间和活化能等参数的影响，及这些参数对弹性体玻璃化转变和分子运动的影响。追踪可逆“牺牲键”的键结构和聚集态结构在应力用下的演变，揭示了该演变过程对能量耗散的作用机制；分析了可逆“牺牲键”网络和共价键网络协同作用产生的应力分散和裂纹钝化作用，揭示了可逆“牺牲键”对弹性体的韧性、断裂能、拉伸强度和自修复效率的作用机制，建立了材料微观结构-宏观性能间的构效关系，为高强度和高韧性弹性体的制备提供一定的理论依据。项目执行期间在Adv Mater, P Natl Acad Sci USA, Sci China Mater, J Mater Chem A, ACS Appl Mater Interfaces, Chem Eng J, Acta Biomater等杂志上发表标注 SCI 论文21篇(其中 IF>10 的期刊论文 5 篇，10>IF>5.0 的期刊论文 10篇)，申请中国发明专利 5项（授权3项），毕业的硕博士研究生6人。