UCLA Researchers Create High-Strength Composites by Upcycling Polymer Foams
Resulting lightweight substances are more sustainable than traditional building materials
Srivastava Lab/UCLA Samueli
Left, a schematic representation of PUC composite fabrication involving the mixing of polyol, toluene diisocyanate linker (TDI) and inorganic clinoptilolite particles. The resulting polyurethane composite is on the right.
UCLA Samueli Newsroom
A team of researchers led by UCLA chemical engineers has discovered a way to make tough and durable composite materials with strength comparable to that of cement by recycling a common polymer foam found in sofas and mattresses.
The discovery was inspired by naturally occurring high-strength materials, such as clamshells or nacre — the shiny material of which pearls are made. These materials are characterized by their unique microscale structure of interconnected plates, which makes them very resistant to cracking under stress. Led by Samanvaya Srivastava, an associate professor of chemical and biomolecular engineering at the UCLA Samueli School of Engineering, the research team aimed to create a synthetic composite material composed of both inorganic and organic phases with comparable strength, which has been a longstanding challenge in the field.
Published in ACS Polymers Au and featured on the journal’s February cover, the study highlights the new material’s rock-like nature. The composite has a lighter weight, requires shorter curing time and possesses stronger bend strength than cement — which, mixed with water or sand, makes concrete for building infrastructure.
“The simplicity of the fabrication approach and the potential of this material for applications in diverse fields really set it apart from other composites,” Srivastava said.
The composite also creates a new recycling route for polyurethane foam, commonly used in furniture like sofas and mattresses or inside vehicles, due to its cushioning properties and durability. Until now, recycling these materials has been challenging, as the resulting products often have inconsistent properties, such as being chemically unstable and having undesirable colors.
“These high-strength composites can perform as excellent thermal and acoustic barriers,” said Divya Iyer, the study’s co-first author and a recent chemical engineering Ph.D. graduate from UCLA Samueli. “To make them, we have designed a chemical pathway to upcycle a common polymer into materials with superior mechanical and functional properties as compared to commercially available materials, including cement.”
Previous attempts to produce similar biologically inspired composite materials predominantly featured metal alloys and minerals, such as aluminum oxide. Unfortunately, these materials require the use of high temperatures and extensive processing. Recent attempts have utilized polymers in combination with inorganic materials, such as graphite and zinc oxide. Polymers are preferable due to their relatively widespread availability, strength and flexibility.
“Our approach is a ‘one-pot process’ that doesn’t require high temperatures or complicated processing conditions,” Srivastava said. “The results also opened a new pathway to recycle materials that would otherwise be directed to landfills — in particular mattresses and car seats. Now we will be able to transform them into high-quality commercial products.”
The new composite material features permanent chemical covalent bonds between recycled organic compound polyols and naturally occurring inorganic materials, which contribute to its strength and durability. In addition to its potential for use as thermal and acoustic insulation, the material could also be used to replace cement, whose manufacturing accounts for about 8% of global carbon dioxide emissions. The researchers said that recycled materials, such as the ones developed in this study, could lead to sustainable alternatives for cement and other building products, including drywall and lightweight concrete.
Other authors of the paper are first co-author Mohammad Galadari and UCLA undergraduate students Fernaldy Wirawan and Vanessa Huaco — all members of the Srivastava Lab. The paper was also authored by Michael Gallagher from the Mattress Recycling Council, a nonprofit organization working to reduce landfill waste. Other UCLA Samueli contributors include Kanji Ono, a professor emeritus of materials science and engineering; Gaurav Sant, a professor of civil and environmental engineering and materials science and engineering; Dante Simonetti, an associate professor of chemical and biomolecular engineering; and mechanical engineering graduate student Ricardo Martinez and his advisor, Laurent Pilon, a professor of mechanical and aerospace engineering and bioengineering. Multiple faculty members from this team are affiliated with the Institute for Carbon Management and the California NanoSystems Institute at UCLA.
The research was funded by the Mattress Recycling Council and the U.S. Department of Energy’s Advanced Research Projects Agency-Energy. The paper was part of the ACS Polymer Au Rising Stars 2023 issue highlighting the work of investigators pioneering exciting research in the field, in which Srivastava was recognized.