Polymer research shows potential replacement for common superglues with a reusable and biodegradable alternative

Good news! 

However, biodegradable makes me a bit doubtful! This is probably the least desirable property in a superglue.

"Researchers have developed an adhesive polymer that is stronger than current commercially available options while also being biodegradable, tunable, and reusable. The findings show how the common, naturally occurring polymer P3HB can be chemically re-engineered for use as a strong yet sustainable bonding agent."

"... how the common, naturally occurring polymer P3HB can be chemically re-engineered for use as a strong yet sustainable bonding agent.  ...

poly(3-hydroxybutyrate), or P3HB, is a natural, biobased and biodegradable polymer that can be produced by microbes under the right biological conditions. While the polymer is not adhesive when made that way, his lab was able to chemically re-engineer its structure to now deliver stronger adhesion than the common petroleum-derived, nonbiodegradable options when used on various substrates or surfaces such as aluminum, glass and wood. The adhesion strength of the re-engineered P3HB can also be tuned to accommodate different application needs. ..."

From the editor's summary and abstract:

"Editor’s summary

From tapes to glues, adhesives are used in a wide range of applications and situations. Most are typically petroleum-based thermoset networks or nonbiodegradable thermoplastic hot melts. Zhang et al. used a set of yttrium-, lanthanum-, and phosphorus-based catalysts to synthesize a series of poly(3-hydroxybutyrate) polymers (P3HBs) with different molecular weights, microstructures, and tacticities. Amorphous polymers tend to be stickier but also weaker, whereas crystalline ones are poor at flowing and filling surface irregularities, which is key to forming a strong bond. The authors found that semicrystalline syndio-rich P3HB not only provides the best adhesion, but can also outperform many commercial alternatives. Because P3HBs are able to be produced by bacteria and can be biodegradable, it may be possible to produce these adhesives in a sustainable way. —Marc S. Lavine

Abstract

Commercial adhesives are petroleum-based thermoset networks or nonbiodegradable thermoplastic hot melts, making them ideal targets for replacement by biodegradable alternatives. Poly(3-hydroxybutyrate) (P3HB) is a biorenewable and biodegradable alternative to conventional plastics, but microbial P3HB, which has a stereoperfect stereomicrostructure, exhibits no adhesion. In this study, by elucidating the fundamental relationship between chemocatalytically engineered P3HB stereomicrostructures and adhesion properties, we found that biodegradable syndio-rich P3HB exhibits high adhesion strength and outperforms common commercial adhesives, whereas syndiotactic, isotactic, or iso-rich P3HB shows no measurable adhesion. The syndio-rich stereomicrostructure brings about desired thermomechanical and viscoelastic properties of P3HB that enable strong adhesion to a range of substrates tested, including aluminum, steel, glass, and wood, and its performance is insensitive to molar mass and reprocessing or reuse."

Polymer research shows potential replacement for common superglues with a reusable and biodegradable alternative | ScienceDaily

Polymer research shows potential replacement for common superglues with a reusable and biodegradable alternative (original news release)

Stereomicrostructure-regulated biodegradable adhesives (no public access)

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No glue required: Wood and metal bonded with sound and 3D printing

Amazing stuff!

Don't get glued to this article! Better to stay glueless! 😊

"... researchers at the Graz University of Technology (TU Graz) in Austria took another approach. Two other approaches, actually, both of which achieved bonds between a variety of wood types and two types of plastics, stainless steel, and a titanium alloy.

In the first, the researchers used a 3D-printing process they termed "Addjoining." They were able to 3D print the various materials directly onto a piece of untreated wood in such a way that they penetrated the pores in the wood, forming a bond in much the same way an adhesive would. The team then snapped the bond apart. ...

The second joining technique the researchers came up with was called "Ultrasonic Joining." It used an instrument called a sonotrode to send high-frequency, low vibration waves through the juncture of the wood and the metal polymers. This created friction, which generated enough heat to bond the two materials together.

..."

No glue required: Wood and metal bonded with sound and 3D printing "Manufacturing could be dramatically changed thanks to two new techniques for joining materials created by scientists in Austria. The two methods create super strong bonds at the pore level, eliminating the need for caustic adhesives."

Alternatives in Car and Aircraft Construction: New Joining and Additive Manufacturing Processes Allow Adhesive-Free Joining of Wood and Metal "Using 3D printing technology and ultrasonic joining technique, researchers at TU Graz succeeded in attaining an extremely strong joining of the renewable raw material wood with metal and polymer composite."

In Ultrasonic Joining, wood and the base component are joined by frictional heat. 

Powerful new adhesive stays strong from freezing to boiling temperatures

Amazing stuff! This what I call a true superglue!

"... The new adhesive belongs to a class known as supramolecular adhesives, which are made up of molecular components specially designed to self-assemble into strong bonds during curing. One is a ring-shaped molecule called a crown ether, which can wrap around the second component, a small protein produced by bacteria. ...
The team tested it out by gluing steel plates together, and found that they could withstand up to 22 Megapascals of shearing force. Most impressively, that strength worked not only at room temperature but anywhere from -196 °C (-320.8 °F) up to 200 °C (392 °F). It proved promising on other materials as well, and even worked underwater. ...
The tight bond drives water out of the protein, which means that when the temperature drops no ice crystals can form and crack open the material, as often happens with other glues. This could also help explain why it works underwater. ..."

From the abstract:

"A crown-ether-protein adhesive was synthesized by host–guest molecular engineering. The internal dynamic molecular interactions endow the adhesives with extraordinary adhesion performance over a wide temperature range from −196 to 200 °C. Extremely strong adhesion, long-lasting adhesion, and biomedical sealing have been achieved. This work offers a promising molecular engineering strategy to fabricate robust supramolecular adhesives for applications under extreme conditions.

The inherently tenuous adhesion strength and limited environmental tolerance of supramolecular adhesives severely restrict their application scenarios. It is challenging for the development of robust adhesives with extreme temperature tolerance. Herein, we report a new type of temperature-resistant crown-ether-protein (CEP) adhesive by harnessing synergistic host–guest molecular interactions between engineered crown ether and protein building blocks. The outputs of CEP adhesive demonstrate ultrahigh shearing adhesion strength of ≈22 MPa over a wide temperature range from −196 to 200 °C, superior to other established supramolecular or polymeric adhesives. The temperature-induced phase transition and internal bound water stabilized the system and led to superb adhesion under extreme conditions. Thus, this work pioneers a molecular engineering approach for the generation of adhesives with tailored applications in extreme settings."

Powerful new adhesive stays strong from freezing to boiling temperatures

Molecular Engineered Crown-Ether-Protein with Strong Adhesion over a Wide Temperature Range from −196 to 200 °C (no public access)