Nature’s frugal glues provide insight for optimized adhesives

Jan 11, 2007 feature
Nature’s frugal glues provide insight for optimized adhesives
This scanning electron micrograph image shows bone glue, which can help bone resist fracture and can heal itself when its bonds break. Image credit: Paul Hansma, et al. J Musculoskelet Neuronal Interact 2005; (5)4:313-315.

In trying to create a “glue” that would hold right up to the breaking point of the material being glued, scientists have found that such an ideal adhesive already exists—in bone, abalone shells, and spider silk, to name a few areas.

What these three natural materials have in common, scientists Paul Hansma, Patricia Turner and Rodney Ruoff found, is an optimized adhesive based on sacrificial bonds and the hidden length mechanism. The scientists foresee that these characteristics may help researchers design and fabricate optimized adhesives for nanocomposite materials, such as carbon nanotubes and graphene sheets.

“It’s important to make a composite material without compromising the material’s properties of the strong components, such as the nanotube or graphene sheet,” Hansma explained to PhysOrg.com. Optimal glue would enable these materials to retain their intrinsic properties—especially strength.

As Hansma et al. explain in their paper in Nanotechnology, optimized adhesives can hold together strong elements of materials, and yield just before these elements would break, so as not to cause the entire structure to break.

To achieve this precise strength and damage resistance, biomaterials make use of sacrificial bonds. These weak bonds form from charged side groups on biological adhesive molecules (such as polymers). With the addition of energy due to the stretching of the material, these weak bonds break—however, the process is reversible, giving the material the ability to heal itself. Human and animals bones, abalone shells, and spider silk all make use of this mechanism of sacrificial bonds and hidden length.

“Abalone shell and bone can heal themselves due to the weak bonds, such as hydrogen bonds or ionic bonds, that can reform,” Hansma explained.

The key to obtaining a perfect amount of adhesive force is to use a precise amount of adhesive itself. Hansma et al. explain that nature acts frugally, with glue often making up as little as one percent of the entire material, by weight. Sometimes, nature even prefers voids over extra glue—which contrasts with current engineering, note the scientists, where the space between elements is often completely filled in with epoxy.

As the scientists explain, the longer the material (such as a steel bar) the lower the percentage of adhesive weight. They point out that one type of material—“ultra-high-molecular-weight polyethylene chains”—is so long that the weak interactions between the chains themselves provide enough adhesion for the structure, and no added glue is needed at all.

“Nature's adhesives tend to be charged polymers, long polypeptides with both positive and negative charged groups along the backbone,” said Hansma. “These adhesives tend to use water as an environment in which weak bonds involving those charged groups can form, break and reform. The challenge will be to simulate these reformable bonds in man-made adhesives.”


Citation: Hansma, P., Turner, P., and Ruoff, R. “Optimized adhesives for strong, lightweight, damage-resistant, nanocomposite materials: new insights from natural materials.” Nanotechnology 18 (2007) 044026 (3pp).

By Lisa Zyga, Copyright 2006 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

Explore further: Demystifying nanocrystal solar cells

add to favorites email to friend print save as pdf

Related Stories

Recommended for you

Demystifying nanocrystal solar cells

Jan 28, 2015

ETH researchers have developed a comprehensive model to explain how electrons flow inside new types of solar cells made of tiny crystals. The model allows for a better understanding of such cells and may ...

Researchers use oxides to flip graphene conductivity

Jan 26, 2015

Graphene, a one-atom thick lattice of carbon atoms, is often touted as a revolutionary material that will take the place of silicon at the heart of electronics. The unmatched speed at which it can move electrons, ...

Researchers make magnetic graphene

Jan 26, 2015

Graphene, a one-atom thick sheet of carbon atoms arranged in a hexagonal lattice, has many desirable properties. Magnetism alas is not one of them. Magnetism can be induced in graphene by doping it with magnetic ...

The latest fashion: Graphene edges can be tailor-made

Jan 23, 2015

Theoretical physicists at Rice University are living on the edge as they study the astounding properties of graphene. In a new study, they figure out how researchers can fracture graphene nanoribbons to get ...

Nanotechnology changes behavior of materials

Jan 23, 2015

One of the reasons solar cells are not used more widely is cost—the materials used to make them most efficient are expensive. Engineers are exploring ways to print solar cells from inks, but the devices ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.