New adhesive made from PLA, mussel glue

ENGINEERS at Purdue University, US, have created a new type of adhesive made from the renewable polymer polylactic acid (PLA) and the proteins which help attach mussels to rocks.

The team, led by Jonathan Wilker, a professor of chemistry and materials engineering, say that the new adhesive is degradable, unlike most conventional petrochemical adhesives. Wilker says that permanent adhesives, like those found in electronics, furniture and vehicles, make disassembly and recycling difficult. Degradable adhesive would make this much faster and easier. The new adhesive also lacks some of the potentially harmful chemicals found in conventional adhesives, such as formaldehyde.

The researchers turned to mussels for inspiration, which use a protein-based ‘glue’ to anchor themselves to rocks. The proteins partially consist of the amino acid DOPA, which is responsible for cross-linking the protein molecules and giving the glue strength. Rather than using proteins, Wilker and the team combine the strength of DOPA with PLA, derived from maize.

“We found the adhesive bonding to be appreciable and comparable to several petroleum-based commercial glues,' Wilker said.

The bonds can be degraded simply using mild hydrolysis conditions, according to the researchers.

“Results presented here show that a promising new adhesive system can be derived from a renewable resource, display high-strength bonding, and easily degrade in a controlled fashion. Particularly unique was the ability to debond this adhesive under mild conditions, said Wilker, adding: “This new system may help lead us toward nontoxic materials sourced from nature, capable of being broken down into benign components, and enhanced recyclability of the products all around us.”

Macromolecules DOI: 10/bxfp