TAGS: Acrylic Coatings Industrial Coatings Sustainability / Natural Coatings
A team of researchers from Japan, led by associate professor Daisuke Suzuki from Shinshu University, develop an innovative way to produce tough and crack-resistant elastic nanoparticle-based latex films without using harmful additives.
It is a new class of latex films composed of rotaxane-crosslinked acrylic nanoparticles. These films exhibit remarkable mechanical properties, including excellent crack-propagation resistance without any additives and are easily recyclable, paving the way for more environmentally friendly materials.
Interlocking Mechanism in Rotaxane
Synthetic latex films, a type of nanoparticle-based films, are widely used across many fields, but they usually contain harmful additives, which are also expensive, to enhance their strength. It is essential to ensure that they are safe, durable and sustainable. This is especially true for synthetic latex films, which are widely used in packaging, biomedicine and electronics.
The key to the approach of the researchers was a novel molecular structure known as rotaxane, which comprises two main components, a ring-like molecule and a linear axle molecule. The ring-like molecule is threaded through the axle molecule, which becomes mechanically trapped thereafter owing to the shape of the axle terminations.
The researchers leveraged this interlocking mechanism in rotaxane by making the ring-like molecule chemically bind to one polymer chain and the axle molecule to another chain. Next, they prepared mixtures of water and polymer nanoparticles through standard ultrasonication and subsequent polymerization that, in turn, were used to produce latex films.
The stretching experiments performed on these films revealed that the rotaxane-based strategy resulted in some remarkable properties.
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In contrast to conventional nanoparticle-based elastic polymers, the latex films composed of the rotaxane-crosslinked nanoparticles exhibited unusual crack propagation behavior,” explained Dr. Suzuki. “
The direction of crack propagation changed from being parallel to the crack to one perpendicular to the crack, resulting in an increased tear resistance.”
Suitable for Developing Additive-free Polymer Films
The new approach to making latex films offers many advantages over conventional methods. Most importantly, no toxic additives are needed to achieve reasonable film toughness. Moreover, since only a tiny amount of rotaxane is needed, the total weight of the films can be kept low while preserving flexibility. The proposed latex films are sustainable as well.
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They are degradable and can be easily disassembled into individual nanoparticles by simply soaking them in an environmentally friendly organic solvent, such as an aqueous ethanol solution,” highlighted Dr. Suzuki. “
These nanoparticles can then form a film again upon evaporation of the solution. The findings of this research can thus help create highly durable and recyclable materials.”
The team expects their work to broaden the scope for the design of new polymer films without additives. Such materials could thus be made biocompatible, with potential applications in biotechnology and medicine in addition to packaging, industrial coatings and adhesives.
Source: Shinshu University