Take two fascinating strong materials, spider silk and carbon nanotubes, and mix them to create a material with a combined strength, toughness and ductility that’s just not been seen before.
If you just want to watch this story, click on the picture video link, otherwise keep reading.
It sounds like a happy weekend in Italy with a picnic story that took a turn for the scientific.
“We randomly selected 15 Pholcidae spiders” starts the supplementary information as the scientists mention areas they collected the spiders from and describe the 4 air holes they put in each of the boxes used to hold the spiders. These boxes coincidentally are the exact same size as my lunch box that I would take on a picnic in the Italian countryside. They they explain how they combined nanotubes or graphene with water and sprayed the spiders in the box with the solution then let them naturally spin their webs.
What they found is that 4 of the spiders died after being sprayed, either due to the spray or being kept in a box I assume. Some spiders made weaker silk, but a few special ones seemed to turn the nanotubes into a part of their silk to create a silk stronger than any known fibre!
With a measured fracture strength (how much force to break) up to 5.4 GPa and a toughness modulus (how much energy absorbed while breaking) up to 2.1 GPa these values surpass synthetic polymeric high performance fibres like Kelvar!
I do believe the results, but having tried to measure the tensile properties of thin strands in my previous job, I do have to address my concerns on the effect of humidity and slip on these types of tests and how difficult they are to carry out, be comparable to tests in other labs and to remove slip and alignment error from. What they are trying to do is not easy and obtaining similar samples to make repeatable tests comparable is also very difficult.
Still, all concerns aside I think it’s a fantastic idea and perhaps a solution to our materials problems of trying to find a glue that sticks individual nanotubes together while keeping the desired properties of both strength and ductility.
The only problem with scaling it up is that many spiders are cannibals, so keeping them apart from each other may be the first priority on the spider farm list. Which incidentally leads on to my next story where Israeli scientists found evidence that Stegodyphys lineatus spiders engage in matriphage, where the mother feeds herself to her young after they hatch.
By releasing her babies from their web cocoon, she then dissolves her intestines and regurgitates this juice for her young until 96% of her mass is used up and only her heart and exoskeleton is left. This process takes about 2 weeks, but she can stop it up to 5 days into the process which is good as if a male spider were to come at this time, he would eat all of her babies, and she could still survive in order to mate with him and repeat the process again with her next set of offspring!
Hmmm, probably not the Mothers Day story you were hoping for.