A folding technique is reported to incorporate large‐area monolayer graphene films in polymer composites for mechanical reinforcement. Compared with the classic stacking method, the folding strategy results in further stiffening, strengthening, and toughening of the composite. By using a water–air‐interface‐facilitated procedure, an A5‐size 400 nm thin polycarbonate (PC) film is folded in half 10 times to a ≈0.4 mm thick material (1024 layers). A large PC/graphene film is also folded by the same process, resulting in a composite with graphene distributed uniformly. A three‐point bending test is performed to study the mechanical performance of the composites. With a low volume fraction of graphene (0.085%), the Young's modulus, strength, and toughness modulus are enhanced in the folded composite by an average of 73.5%, 73.2%, and 59.1%, respectively, versus the pristine stacked polymer films, or 40.2%, 38.5%, and 37.3% versus the folded polymer film, proving a remarkable mechanical reinforcement from the combined folding and reinforcement of graphene. These results are rationalized with combined theoretical and computational analyses, which also allow the synergistic behavior between the reinforcement and folding to be quantified. The folding approach could be extended/applied to other 2D nanomaterials to design and make macroscale laminated composites with enhanced mechanical properties.

中文翻译：

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折叠大的石墨烯-聚合物薄膜可增强层压复合材料的机械性能

据报道，一种折叠技术将大面积的单层石墨烯薄膜掺入了聚合物复合材料中，以进行机械加固。与经典的堆叠方法相比，折叠策略可进一步增强复合材料的硬度，强度和韧性。通过使用水-空气界面简化程序，将A5尺寸的400 nm聚碳酸酯（PC）薄膜对折10倍，形成≈0.4mm厚的材料（1024层）。大型PC /石墨烯薄膜也可以通过相同的方法折叠，从而形成具有均匀分布的石墨烯的复合材料。进行了三点弯曲测试，以研究复合材料的机械性能。使用低体积分数的石墨烯（0.085％），折叠后的复合材料的杨氏模量，强度和韧性模量平均提高了73.5％，73.2％和59.1％，相对于原始堆叠的聚合物膜分别为40.2％，38.5％和37.3％，相对于折叠的聚合物膜而言，石墨烯的折叠和增强相结合提供了显着的机械增强。这些结果通过理论分析和计算分析相结合得到了合理化，这也使得加固和折叠之间的协同行为得以量化。折叠方法可以扩展/应用于其他2D纳米材料，以设计和制造具有增强的机械性能的宏观层压复合材料。这也可以量化加固和折叠之间的协同行为。折叠方法可以扩展/应用于其他2D纳米材料，以设计和制造具有增强的机械性能的宏观层压复合材料。这也可以量化加固和折叠之间的协同行为。折叠方法可以扩展/应用于其他2D纳米材料，以设计和制造具有增强的机械性能的宏观层压复合材料。