Research

Each year, over 400 million metric tons of plastics are produced and used worldwide, yet less than 10% of these plastics is recycled or reused. The Liu Group is addressing this global plastic waste crisis by converting plastic waste into high-value chemicals and materials, creating strong financial incentives for plastic recyclers. This approach offers a range of benefits: 1) opening new opportunities for profitable plastic waste recycling, 2) reinforcing the chemical and materials supply chain by providing alternative feedstocks, and 3) fostering global sustainability and social responsibility. Importantly, we focus on low-cost, high-value, and industrially scalable chemical approaches.

The Liu Group has developed a range of innovative processes to upcycle plastic waste. We have pioneered the conversion of polystyrene waste into benzene, a platform chemical that can be further transformed into high-value products such as fragrances, pharmaceutical precursors, and cosmetic additives. Additionally, we have developed methods to convert mixed polyethylene and polypropylene into platform chemical alpha-olefins with controlled chain lengths. A key achievement of our research has been the upcycling of these waste-derived alpha-olefins into high-value surfactants used in household products (such as soaps and detergents) and industrial applications (like emulsifiers). Notably, these high-value materials share similar market sizes of end-of-life plastic waste.

In broader areas of sustainable chemistry and engineering, the Liu group has developed one of the world’s thinnest and strongest polymer-graphene heterostructural membranes, capable of being tensioned across inch-diameter areas. These membranes have been used in electrostatic acoustic speakers, delivering over ten times the energy efficiency of conventional electrodynamic speakers. Additionally, we have created a new class of carbon fibers, derived from block copolymers, which offer exceptionally uniform mesoporous structures, along with hierarchical macropores and micropores. These block copolymer-derived porous carbon fibers are now used in a variety of applications, including energy storage (e.g., batteries and supercapacitors), water treatment (e.g., desalination and contaminant removal), gas separation, and electrochemical catalysis.

The research in the Liu group has received global recognition, featured by hundreds of news media including NPR, Fox News, ABC, BBC, The Guardian, the World Economic Forum, Irish National Radio, and New Zealand National Radio.

Overall, the Liu group has three directions (click the links to see more details):

1. synthesis and upcycling of polymer materials (link)

2. polymer derived porous carbon fibers and ceramics (link) 

3. thin film polymer composites (link)