Conductive Synthetic Polymers Inspired by Spider Silk

Innovation: Academia

University of Groningen

2020

Image: Jack van der Spoel / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Modify Size/Shape/Mass/Volume

Many living systems alter their physical properties, such as size, shape, mass, or volume. These modifications occur in response to the living system’s needs and/or changing environmental conditions. For example, they may do this to move more efficiently, escape predators, recover from damage, or for many other reasons. These modifications require appropriate response rates and levels. Modifying any of these properties requires materials to enable such changes, cues to make the changes, and mechanisms to control them. An example is the porcupine fish, which protects itself from predators by taking sips of water or air to inflate its body and to erect spines embedded in its skin.

Search this Function

Modify Material Characteristics

The materials found in living systems are variable, yet often made from the same basic building blocks. For example, all insect exoskeletons consist of a material called chitin. Because material resources are limited, each material within or used by a given living system must frequently serve multiple purposes. Therefore, living systems have strategies to modify materials’ softness, flexibility, and other characteristics. To ensure survival, the benefits of these modifications must outweigh the living system’s energy and material expenditure to generate them. For example, spiders store the liquid components of spider silk in a gland, converting them into silk thread when needed. Some threads have different characteristics, such as elasticity and UV reflectance, than others.

Search this Function

Modify Electric Charge

Harnessing the power of electricity can be a powerful way for organisms to get energy. An electric charge can be positive or negative. When matter with an electric charge is near other charged particles, it will either be ‘repulsed’ or ‘attracted’ to the matter based on the charge. From electric eels to oriental hornets, learn about the different ways organisms use electric charges to their advantage.

Search this Function

Biomaterial from University of Groningen uses protein-like synthetic polymers to increase proton conductivity.

Benefits

Durable
Versatile
Increased conductivity

Applications

Bio-electronics
Energy storage
Sensors

UN Sustainable Development Goals Addressed

Goal 9: Industry Innovation & Infrastructure
Goal 12: Responsible Production & Consumption

The Challenge

Synthetic polymers can be found in a variety of places, including clothing, furniture, and plastics. Although they are useful, it is challenging to accurately control their molecular structure. This structure controls many properties, including the ability to transport ions. If synthetic polymers used as biomaterials could be more accurately constructed, the ion transport could be optimized, and the material would perform better. Proton-conducting bio-polymers could be very useful for applications such as bio-electronics or sensors.

Innovation Details

The best way to precisely tune the proton conductivity of s is to tune the number of ionisable groups per polymer chain. To do this, the researchers first prepared a number of unstructured biopolymers that had different numbers of ionisable (carboxylic acid) groups. With the right nanostructure, charges will bundle together and increase the local concentration of these ionic groups, which dramatically boosts proton conductivity. It turns out that the nanostructure of spider silk is excellent for this task. The researchers engineered a protein-like polymer that has the main structure of spider silk but was modified to host strands of carbocyclic acid. The material was able to self-assemble at the nanoscale similarly to spider silk while creating dense clusters of charged groups, which are very beneficial for the proton conductivity. The measured proton conductivity was higher than any previously known biomaterials

Biological Model

Spider silk is extremely strong and flexible despite being an incredibly thin and lightweight material. This is due in part to the supramolecular structure in which chains are interlinked to help provide high stability.

See Related Strategy

black, yellow, and white spider on web during the daytime

Biological Strategy

Spider Web Is Strong and Elastic

Webs of orb spiders are elastic and strong because of sacrificial bonds that break and then reform

References

Journal article

De novo rational design of a freestanding, supercharged polypeptide, proton-conducting membrane

Science Advances

embedly preview

AskNature