Newly developed microlattices are lighter and 100 times stronger than regular polymers

Newly developed 'microlattices' are lighter and 100 times stronger than regular polymers

Examples of coronary stents with the 3D-printed partially carbonized core.

As said, the most effective approach for increasing the strength of these 3D printable polymer lattices is pyrolysis.

Professor Lu discovered a “magic-like” circumstance in the pyrolysis of the 3D-printed photopolymer microlattices, which caused a 100-fold increase in strength and a two-fold increase in ductility of the original material.

To get the best strength and ductility, the proportion of polymer to carbon fragments is also essential. The material loses strength if there are too few carbon pieces, and it becomes brittle if there are too many. The researchers successfully developed an ideally carbonized polymer lattice throughout the study.

The research team also found that these “hybrid carbon” microlattices showed improved biocompatibility compared to the original polymer.

“Our work provides a low-cost, simple, and scalable route for making lightweight, strong and ductile mechanical metamaterials with virtually any geometry,” said Professor Lu.

The research was supported by CityU, the Hong Kong Institute for Advanced Study, the Shenzhen Science and Technology Innovation Committee, and the National Natural Science Foundation of China.

Study abstract

A lightweight material with simultaneous high strength and ductility can be dubbed the “Holy Grail” of structural materials, but these properties are generally mutually exclusive. Thus far, pyrolytic carbon micro/nanolattices are a premium solution for ultra-high strength at low densities, but intrinsic brittleness and low toughness limits their structural applications. Here, we break the perception of pyrolyzed materials by demonstrating a low-cost, facile pyrolysis process, i.e., partial carbonization, to drastically enhance both the strength and ductility of a three-dimensional (3D)-printed brittle photopolymer microlattice simultaneously, resulting in ultra-high specific energy absorption of up to 60 J g−1 (>100 times higher than the original) without fracture at strains above 50%. Furthermore, the partially carbonized microlattice shows improved biocompatibility over its pure polymer counterpart, potentially unlocking its biomedical and multifunctional applications. This method would allow a new class of hybrid carbon mechanical metamaterials with lightweight, high toughness, and virtually any geometry.

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