Abstract The self-organization of macromolecules on solid surfaces represents a topic of great current interest. Here, solvent-free interactions between polyolefins and silicon substrates are investigated upon their physical vapor deposition under vacuum. Molecular dynamics simulations show that polyolefins unfold upon adsorption and that two macromolecules suffice to produce a stable nucleus. Supersharp probe AFM measurements reveal the formation of 3.5 nm globular clusters that further transform into two-dimensional islands with compact shapes that possess a 3.5 nm thick rim and a 7.0 nm thick center. The islands grow via attachment-limited aggregation by accepting new molecules from the edge, keeping the thickness constant and expanding laterally. The evolution of the island growth is analyzed within the framework of capture zone distribution analysis using generalized Wigner scaling. The critical island size is found to be 1, confirming the results of molecular dynamics simulations. Upon longer deposition times, the islands coalesce, whereas their surface smoothens with a growth exponent of γ = -0.33 and a dynamic exponent of 1/z = -0.21. Smoothening is accompanied by crystallization phenomena that result in the formation of orthorhombic polyolefin crystals, as detected by XRD.

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固/真空界面处气相沉积聚烯烃的自组织

摘要 大分子在固体表面上的自组织是当前非常受关注的一个话题。在这里，聚烯烃和硅基板之间的无溶剂相互作用在真空下的物理气相沉积中进行了研究。分子动力学模拟表明，聚烯烃在吸附时展开，两个大分子足以产生一个稳定的核。Supersharp 探针 AFM 测量揭示了 3.5 nm 球状星团的形成，这些球状星团进一步转变为具有紧凑形状的二维岛，这些岛具有 3.5 nm 厚的边缘和 7.0 nm 厚的中心。这些岛通过接受来自边缘的新分子、保持厚度恒定和横向扩展，通过附着限制聚合而生长。在使用广义 Wigner 标度的捕获区分布分析框架内分析岛屿增长的演变。发现临界岛尺寸为 1，证实了分子动力学模拟的结果。在更长的沉积时间后，这些岛会合并，而它们的表面会变得平滑，增长指数为 γ = -0.33，动态指数为 1/z = -0.21。平滑伴随着结晶现象，导致正交聚烯烃晶体的形成，如通过 XRD 检测到的。