An official website of the United States government
Abstract Biodegradable plastics, perceived as ‘environmentally friendly’ materials, may end up in natural environments. This impact is often overlooked in the literature due to a lack of assessment methods. This study develops an integrated life cycle impact assessment methodology to assess the climate-change and aquatic-ecotoxicity impacts of biodegradable microplastics in freshwater ecosystems. Our results reveal that highly biodegradable microplastics have lower aquatic ecotoxicity but higher greenhouse gas (GHG) emissions. The extent of burden shifting depends on microplastic size and density. Plastic biodegradation in natural environments can result in higher GHG emissions than biodegradation in engineered end of life (for example, anaerobic digestion), contributing substantially to the life cycle GHG emissions of biodegradable plastics (excluding the use phase). A sensitivity analysis identified critical biodegradation rates for different plastic sizes that result in maximum GHG emissions. This work advances understanding of the environmental impacts of biodegradable plastics, providing an approach for the assessment and design of future plastics.
more »
« less
Machine intelligence-accelerated discovery of all-natural plastic substitutes
Abstract One possible solution against the accumulation of petrochemical plastics in natural environments is to develop biodegradable plastic substitutes using natural components. However, discovering all-natural alternatives that meet specific properties, such as optical transparency, fire retardancy and mechanical resilience, which have made petrochemical plastics successful, remains challenging. Current approaches still rely on iterative optimization experiments. Here we show an integrated workflow that combines robotics and machine learning to accelerate the discovery of all-natural plastic substitutes with programmable optical, thermal and mechanical properties. First, an automated pipetting robot is commanded to prepare 286 nanocomposite films with various properties to train a support-vector machine classifier. Next, through 14 active learning loops with data augmentation, 135 all-natural nanocomposites are fabricated stagewise, establishing an artificial neural network prediction model. We demonstrate that the prediction model can conduct a two-way design task: (1) predicting the physicochemical properties of an all-natural nanocomposite from its composition and (2) automating the inverse design of biodegradable plastic substitutes that fulfils various user-specific requirements. By harnessing the model’s prediction capabilities, we prepare several all-natural substitutes, that could replace non-biodegradable counterparts as exhibiting analogous properties. Our methodology integrates robot-assisted experiments, machine intelligence and simulation tools to accelerate the discovery and design of eco-friendly plastic substitutes starting from building blocks taken from the generally-recognized-as-safe database.
more »
« less
- Award ID(s):
- 1936452
- PAR ID:
- 10534787
- Publisher / Repository:
- Nature
- Date Published:
- Journal Name:
- Nature Nanotechnology
- Volume:
- 19
- Issue:
- 6
- ISSN:
- 1748-3387
- Page Range / eLocation ID:
- 782 to 791
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
null (Ed.)Petrochemical-based plastics have not only contaminated all parts of the globe, but are also causing potentially irreversible damage to our ecosystem because of their non-biodegradability. As bioplastics are limited in number, there is an urgent need to design and develop more biodegradable alternatives to mitigate the plastic menace. In this regard, we report aquaplastic, a new class of microbial biofilm-based biodegradable bioplastic that is water-processable, robust, templatable and coatable. Here, Escherichia coli was genetically engineered to produce protein-based hydrogels, which are cast and dried under ambient conditions to produce aquaplastic, which can withstand strong acid/base and organic solvents. In addition, aquaplastic can be healed and welded to form three-dimensional architectures using water. The combination of straightforward microbial fabrication, water processability and biodegradability makes aquaplastic a unique material worthy of further exploration for packaging and coating applications.more » « less
-
Abstract Biodegradable plastics have been proposed as an alternative to conventional plastics for many applications, such as single-use plastic bags, disposable cutleries and tablewares, and agricultural plastic mulch films. However, concerns have arisen about environmental sustainability of biodegradable plastics, especially regarding degradability, generation of biodegradable micro- and nanoplastics, and release of additives. Here, we critically evaluate literature on the degradation and ecotoxicity of biodegradable plastics with the consideration of environmentally relevant concentrations. Our evaluation suggests that, provided with proper disposal and full biodegradation, biodegradable plastics, including biodegradable micro- and nanoplastics, would not accumulate substantially in the environment and would be far from reaching concentrations at which negative impacts on ecosystems can be expected. In addition, we highlight existing regulatory efforts to prevent adverse ecotoxicity of biodegradable plastics. To ensure timely biodegradation under various disposal conditions, we propose to calibrate the actual biodegradability in disposal environments against the intrinsic biodegradability in standards. Further, we recommend to supplement biodegradability certificates on biodegradable plastics with clear disposal instructions, to ensure proper end-of-life management. With proper testing, comprehensive labeling, and effective management, we believe that, for certain applications, biodegradable plastics are a promising substitute for conventional plastics.more » « less
-
ABSTRACT Sustainable alternatives to petroleum‐based plastics are needed urgently, but biodegradable materials from renewable sources often suffer from inadequate mechanical properties. Here, we demonstrate a bio‐inspired strategy to enhance soy protein isolate (SPI) nanocomposites through surface modification of cellulose nanocrystal (CNC) reinforcing filler particles with a polydopamine (polyDOPA) coating via dopamine polymerization under alkaline conditions. This modification creates multifunctional interfaces at filler surfaces that enhance nanocomposite mechanical properties likely by simultaneously altering filler dispersion and filler–matrix interactions. PolyDOPA‐modified CNCs increase the tensile strength and elastic modulus of SPI films (plasticized with 50% glycerol) by more than threefold compared to unreinforced controls. Transmission electron microscopy, spectroscopic techniques, and thermal analysis reveal that polyDOPA coatings influenced nanocomposite structure across multiple length scales, tripling the effective diameter of the CNC inclusions, reducing the tendency of CNC nanocrystals to aggregate, and increasing the glass transition temperature. The increase in glass transition temperature suggests reduced SPI molecular mobility, which, along with micromechanical modeling, indicates the potential for improved interfacial interactions. Results reveal how polyDOPA‐modified CNCs influence the interphase behavior and filler dispersion of SPI‐glycerol nanocomposites, providing a pathway to further improve their performance for various applications, including packaging, membranes, and coatings.more » « less
-
Abstract Creating a sustainable economy for plastics demands the exploration of new strategies for efficient management of mixed plastic waste. The inherent incompatibility of different plastics poses a major challenge in plastic mechanical recycling, resulting in phase‐separated materials with inferior mechanical properties. Here, this study presents a robust and efficient dynamic crosslinking chemistry that effectively compatibilizes mixed plastics. Composed of aromatic sulfonyl azides, the dynamic crosslinker shows high thermal stability and generates singlet nitrene species in situ during solvent‐free melt‐extrusion, effectively promoting C─H insertion across diverse plastics. This new method demonstrates successful compatibilization of binary polymer blends and model mixed plastics, enhancing mechanical performance and improving phase morphology. It holds promise for managing mixed plastic waste, supporting a more sustainable lifecycle for plastics.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s41565-024-01635-z
