Fundamental research to make paint more environmentally sound

In collaboration with Allnex Industries, a team from the Centre for Advanced Macromolecular Design (CAMD) in the School of Chemical Engineering at UNSW is well on the way to developing environmentally friendly high-performance waterborne coatings to replace the more toxic solvent-based alternatives.

“The commercial and practical importance of coatings, such as paints, in today’s society can hardly be overstated,” says Professor Per Zetterlund who is the Co-Director of UNSW’s Centre for Advanced Macromolecular Design.

According to Zetterlund, coatings can either be solvent-based or waterborne, but he says that with the ongoing drive towards more environmentally friendly coatings, there is a strong need to replace traditional solvent-based coatings with entirely waterborne systeA waterborne coating (paint) is an aqueous dispersion of polymer nanoparticles (a “latex”). The internal particle morphology (illustrated with shades of blue/red of an individual particle) has a great impact on the properties of the dried film after application to a range of productsms.

“Waterborne coatings are a key measure by which the coating industry is able to meet legislative and environmental requirements to reduce their emissions of anthropogenic Volatile Organic Compounds (VOCs), which have been identified as key agents in long-term health impacts,” he explains.

Although the industry is facing increased regulation in an effort to improve interior and exterior air quality, there are still hurdles to overcome because without the use of VOCs, current waterborne coatings exhibit crucial shortcomings related to film formation. This includes poor gloss, cracking, and poor moisture and chemical resistance. Moreover, extensive use of VOC additives is not only undesirable from an environmental perspective, but also compromises properties such as drying rate, hardness build-up, and in some cases chemical resistance.

In order to address these shortcomings, Zetterlund and his team joined forces with partner organisation Allnex Industries (who do a lot of work on different types of polymer resins, paints and coatings) on a project to develop clean and effective waterborne coatings.

“Current practice in industry has been to mainly rely on a trial-and-error approach, which can be time-consuming, expensive and may not lead to optimum products. This project is looking to develop a quantitative understanding of the relationship between the method of polymer particle synthesis, the morphology of composite polymer particles, and the properties of the final polymer film,” continues Zetterlund.

They have made great progress as Zetterlund explains: “The biggest outcome so far is that we have developed a completely new way to characterise the internal morphology of these so-called gradient nanoparticles based on a method called XPS [X-ray photoelectron spectroscopy]. The other important thing we’ve achieved is a good understanding on a mechanistic level of how to design a process in order to obtain polymeric nanoparticles with a specific internal structure. The remaining task is to link these two with the properties of the final films.”

Zetterlund says the four-year Linkage grant ends in March 2018, but he is very hopeful the research will continue with a second Linkage grant and will soon be travelling to Allnex headquarters in The Netherlands to discuss future steps.

“For Allnex Industries, working with Per Zetterlund’s group has provided a great platform for in-depth scientific discussions on complex issues related to real-life production processes. The collaboration has provided us with new methods to answer questions that we only had assumptions on before, leading to the adaptation of some of them, and triggering new ideas on how to improve our products.” 

Dr Richard Brinkhuis, Allnex Industries

 

Partnership in summary

Partner: Allnex Industries (formerly Nuplex Industries)

Type of partnership: Initially, contract research; then continued with an Australian Research Council (ARC) Linkage Project grant.

Funding: $300,000 from ARC and $200,000 from Allnex, plus in-kind provisions.

Purpose: Develop environmentally friendly high-performance waterborne coatings that will enable the replacement of currently employed solvent-based systems.

Outcomes: 1: A completely new way to characterise the internal morphology of gradient nanoparticles using a method based on X-ray photoelectron spectroscopy.

2: Mechanistic understanding of how to design a process in order to obtain polymeric nanoparticles with a specific internal structure.

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