New polymer gives 3D printed sand super-strength

Described in Nature Communications, the polymer was used to create a 6.5cm long bridge able to support 300 times its own weight – the equivalent to the Brooklyn Bridge supporting 12 Empire State Buildings. The scientists behind the discovery say that sand parts embedded with the new polymer could be used as durable casts for tooling or carbon fibre manufacturing.

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To achieve these exceptional levels of strength, the sand was printed in combination with a tailored polyethyleneimine (PEI) binder that initially doubled the strength of parts versus existing binders. Post-printing, the parts were then treated with a superglue-type material called cyanoacrylate, which penetrates gaps and brings an additional eight-fold increase in strength. According to the researchers, the resulting polymer sand composite is stronger than any other known building material, including masonry.