Graphene oxide (GO) featuring a two-dimensional (2D) sheetlike structure and extensive oxygen functionalities occupies indispensable research branches in polymer composites. Key to the property translation from GO nanosheets to host polymers is the proper exfoliation and controlled dispersion that are profoundly governed by the competitive evolution between GO–GO intersheet attractions and GO–polymer interfacial interactions. Here, a microwave-assisted synthetic approach was proposed to enable direct in situ growth of carbon nanotubes (CNTs) at GO templates, engendering a minute-level and one-pot route to create three-dimensional (3D) hierarchical nanohybrids (GO@CNT). Featuring a unique 3D structure, the nanohybrids were homogeneously dispersed and properly exfoliated in racemic polylactide (PLA) blends, in clear contrast to microscale local aggregation of GO due to extensive intersheet attractions. Albeit present at an extremely low amount (0.05 wt %), GO@CNT significantly outperformed GO in terms of boosting PLA stereocomplexation, achieving distinct overall improvements in gas barrier performance (oxygen permeability coefficient as low as 0.25 × 10^–15 cm³ cm cm^–2 s^–1 Pa^–1) and mechanical properties (tensile strength of ∼70 MPa and Young’s modulus of ∼2 GPa) for stereocomplexed PLAs. This work affords elucidation of direct covalent functionalization of 2D nanosheets and property-by-morphology understanding in polymer composites, which may motivate further extension to other 2D/one-dimensional (1D) hierarchical hybrids in need for the fabrication of multifunctional polymer composites.

中文翻译：

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微波辅助在氧化石墨烯纳米片上直接生长碳纳米管以促进聚交酯的立体络合和性能

具有二维（2D）片状结构和广泛的氧官能团的氧化石墨烯（GO）在聚合物复合材料中占据着不可或缺的研究分支。从 GO 纳米片到主体聚合物的性质转化的关键是适当的剥离和受控分散，这在很大程度上受 GO-GO 层间吸引力和 GO-聚合物界面相互作用之间的竞争演化控制。在这里，提出了一种微波辅助合成方法，以实现直接原位在 GO 模板上生长碳纳米管 (CNT)，产生了一种分钟级和一锅法来创建三维 (3D) 分层纳米杂化物 (GO@CNT)。纳米杂化物具有独特的 3D 结构，在外消旋聚丙交酯 (PLA) 混合物中均匀分散和适当剥离，这与由于广泛的层间吸引力而形成的 GO 微尺度局部聚集形成鲜明对比。尽管存在量极低（0.05 wt%），但 GO@CNT 在促进 PLA 立体络合方面显着优于 GO，实现了气体阻隔性能的显着整体改进（氧气渗透系数低至 0.25 × 10 ^–15 cm ³ cm cm ^–2秒^–1帕^–1) 和立体络合 PLA 的机械性能（抗拉强度约为 70 MPa，杨氏模量约为 2 GPa）。这项工作阐明了二维纳米片的直接共价功能化和聚合物复合材料中的形态学理解，这可能会促使进一步扩展到制造多功能聚合物复合材料所需的其他二维/一维（1D）分层杂化物。