Performing Department
Biological & Environmental Engineering
Non Technical Summary
Plastic waste is perhaps one of the most critical issues in our modern society. Most plastics are made from petrochemicals, whose wastes are inherently difficult to be degraded and are increasingly polluting our environment. Cellulose and sugar-based degradable plastics (bioplastics) have been developed to solve this issue so far, but yet, high energy consumption and severe conditions are required for both synthesis and degradation. Also, the feedstock for bioplastics are highly competing with agricultural resources including farmland and water. A novel strategy that allows natural biodegradation (composting) and an environmentally benign lifecycle is thus in urgent need. DNA biomass, one of the most abundant natural resources on this planet (e.g., food waste), has not yet been utilized as materials. Recently, we invented a cost-effective route to create plastics from biomass DNA. A prototype plastic has already been created from various biomass, from algae to bacteria to plants to food waste, spanning at least three kingdoms. Both environmentally benign synthesis and complete degradation under mild conditions were also demonstrated. Based on this background, we aim to create a bio-petro hybrid plastics called "D-plastics", which can achieve both mechanical strength and tunable biodegradability. Two synthesis routes for various practical uses and tunable natural biodegradation will be investigated. With this innovative approach, we will not only realize complete degradation but also reduce the energy consumption, paving a route to a sustainable future.
Animal Health Component
40%
Research Effort Categories
Basic
30%
Applied
40%
Developmental
30%
Goals / Objectives
1) Establishing a large-scale synthesis route of D-plastics for two classes of products: "hard" plastic products (rigid objects including toys and disposable cups) and "soft" plastic products (including disposable bags and fabrics).2) Characterizing the structural and mechanical properties of the D-plastics; and3) Developing "smart depolymerization" in two flavors: a long-term depolymerization/degradation and a short-term depolymerization/degradation for both hard and soft D-plastic products.
Project Methods
We will create biomass DNA-plastics (D-plastics) by a bio-petro hybrid approach where biomass DNA and existing petrochemicals will be combined to achieve both mechanical strengths and tunable biodegradability. Instead of using the traditional organic synthesis approach, we aim to use biomass DNA themselves as connectors/crosslinkers to link conventional petro-polymers into hybrid plastics. We will start with polyurethane, polyethylene, and polyester in their oligomeric states to demonstrate the concept and the versatility of our platform. These petro-molecules will provide the desired mechanical properties of plastics, while biomass DNA molecules will confer the tunable depolymerization. We will aim at two classes of final plastic products: 1) a "hard" plastic product (rigid objects) and 2) a "soft" plastic product (fabrics). Various traditional plastic manufacturing processes will be adopted for D-plastics depending on the processing volumes, such as casting, extrusion, molding, and 3D printing. Final proposed products will be single-use cups and plastic toys for our "hard" D-plastics and disposable plastic bags and also textiles for our "soft" plastics. Two crosslinking approaches will be used for the synthesis: chemical and physical linking. The chemical linking route is based on a series of existing, industry-scale chemical reactions. We will utilize a hydroxyl group at the 3' end of DNA to create a covalent bonding between DNA chains and plastic oligomers. Polyurethane and polyester will be employed for the initial targets. Extracted biomass DNA will be mixed and reacted with petro-oligomers after DNA is introduced to an organic phase via a unique phase transfer catalyst that we discovered recently. Concurrently, we will explore the physical linking via massive hydrogen bonding that will provide an alternative route for the fabrication of D-plastics. D-plastics will be fabricated as supramolecular polymers by massive base pairings and intermolecular entanglement. The tunable degradation will be tested by utilizing biochemical reactions that happen all the time in ocean and soil - nucleic acid degradation via composting. Since we have already demonstrated the biodegradation of pure biomass DNA-based plastics, for D-plastics, we will focus on a more quantitative assessment in real-world environments. For instance, we will apply international standard testing methods, such as ASTM G21-15, D7473-12, and D5247-92. To further optimize our D-plastics, we will systematically explore the parameter space and establish semi-quantitative relationships to provide optimized synthesis recipes tailored to the lifetime of products.