A team working out of University of California at Santa Barbara has found a way to 3D print with so-called “bottlebrush” elastomers, or molecules with long “backbones” of polymers with linking polymers hanging off them. This discovery is particularly useful because the material has a novel texture: soft and elastic, much like human tissue.
Elastomers are a general name for stretchy polymers like rubber. Currently, we can print with linear elastomers, or stiffer materials made up of long, straight chains of molecules. But bottlebrush polymers are another story. So-named because they have little polymer “bristles” hanging off the linear “brush” of the main polymer, bottlebrush polymers feature a structure that allows them link together to form softer materials.
Right now, bottlebrush polymers can only be produced by more time-consuming simple molding procedures. A study published earlier this month in Science Advances might change that, however. Postdoctoral researcher Sanjoy Mukherjee discovered a new polymer by accident: a semi-soft solid that holds its shape, but will go liquid at room temperature in response to pressure (otherwise known as a yield stress fluid). This reaction is reversible, meaning that it can be liquified to pass through a syringe, and then become solid again on the other side. This property comes from the bottlebrush polymers “self-assembling” into a solid with bonds weak enough that they’ll yield under pressure.
The property means it can be printed via Direct Ink Writing: passing low-viscosity ink through a nozzle or syringe to solidify after it prints. The team, headed by Mukherjee and colleague Renxuan Xie, printed the material using a modified LulzBot TAZ Workhorse. After printing, the team bathed their test items in UV light to cure them. This was possible because of a photocrosslinker added to the polymer, which connected nearby polymers to make the printed product permanently solid.
The bottlebrush polymer has very unique properties.
“The modulus of our material is a thousand times smaller than that of a rubber band,” said Xie. “It is super-soft—it feels very much like human tissue—and very stretchy. It can stretch about three to four times its length.”
Just as remarkably, the material is soft and stretchy without the need for water or solvents.
“People often add solvent to liquify a solid so that it can be squeezed out of a nozzle,” Xie added, “but if you add solvent, it has to evaporate after printing, causing the object to change its shape or crack.”
The new polymer has the potential to be very useful, especially in printing biomimetic tissue or touch-sensitive electronics. The team is particularly excited about the potential for using it in medical applications. Their paper points out that the end groups on the polymers are benzophenones, which are generally well-tolerated by the body. And the material’s texture may help.
“These super-soft elastomers might be applicable as implants,” said Christopher Bates, an assistant professor of materials, and the head of one of the labs where the research was conducted. “You may be able to reduce inflammation and rejection by the body if the mechanical properties of an implant match native tissue.”
Subscribe to Our Email Newsletter
Stay up-to-date on all the latest news from the 3D printing industry and receive information and offers from third party vendors.
You May Also Like
Additive Manufacturing Strategies 2024: Choose Your Own Adventure
Additive Manufacturing Strategies (AMS) in New York City is my favorite AM industry event. Now, I work for the company that puts on the show, so I’m sure I would...
3D Printing Webinar and Event Roundup: February 18, 2024
Kicking things off in this week’s 3D Printing Webinar and Event Roundup, SPE’s International Polyolefins Conference is taking place in Texas, while the WAMSymposium will be held in Florida and...
Where Have All AM’s Unicorns Gone?
In the rapidly evolving world of 3D printing, startups valued at over a billion dollars, known as unicorns, once seemed as fantastical as the mythical creatures themselves. While a few...
Streamlining 3D Printing: HP’s Global Head of Polymers Discusses the AM I Navigator Initiative
As happens every year at Formnext, the world’s largest 3D printing trade show, a number of different significant product launches, mergers, and other announcements took place at Formnext 2023. Perhaps...
Upload your 3D Models and get them printed quickly and efficiently.