Kurbatov Andrey O, Balabaev Nikolay K, Litvin Kirill A, Kramarenko Elena Yu
Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia.
Enikolopov Institute of Synthetic Polymeric Materials RAS, Moscow 119991, Russia.
Polymers (Basel). 2023 Oct 10;15(20):4040. doi: 10.3390/polym15204040.
Due to the absence of specific interactions, carbosilane dendrimers are ideal models to study the effect of a hyperbranched regular structure on the molecular response to external influences. In this work, we have studied the conformational behavior of single polybutylcarbosilane dendrimers under confinement between impermeable flat surfaces using atomistic molecular dynamics simulations. Dendrimers of different generations belonging to two homologous series with a tetra-functional core and three- and four-functional branches were simulated. The analysis of the dependence of the internal energy of the dendrimers on the wall distance allowed us to determine the critical degree of compression at which the dendrimers are able to change their shape without energy loss. The effects of generation number and branching functionality on the number of wall contacts, density distribution and shape changes were elucidated. It was found that for high generation dendrimers, the inner layers are not accessible for external interaction. It was shown that the excess stresses occurring at high compressions are concentrated in the structural center of the dendrimer. The nature of the elastic response, which is strongly nonlinear, was analyzed at different compressions depending on the dendrimer architecture and generation. We believe that our results are useful for further studies of dendrimer films under compression and can also serve as a basis for developing model concepts to describe the dynamics of dendrimer melts.
由于不存在特定相互作用，碳硅烷树枝状大分子是研究超支化规则结构对分子对外界影响响应的理想模型。在这项工作中，我们使用原子分子动力学模拟研究了单个聚丁基碳硅烷树枝状大分子在不可渗透平面之间受限情况下的构象行为。模拟了属于两个同源系列的不同代数树枝状大分子，其具有四官能团核心以及三官能团和四官能团分支。通过分析树枝状大分子内能对壁间距的依赖性，我们确定了树枝状大分子能够在不损失能量的情况下改变形状的临界压缩程度。阐明了代数和分支官能团对壁接触数、密度分布和形状变化的影响。发现对于高代数树枝状大分子，内层无法进行外部相互作用。结果表明，在高压缩下出现的额外应力集中在树枝状大分子的结构中心。根据树枝状大分子的结构和代数，分析了在不同压缩下强烈非线性的弹性响应的性质。我们相信我们的结果对于进一步研究压缩下的树枝状大分子薄膜是有用的，也可为开发描述树枝状大分子熔体动力学的模型概念提供基础。
