Sustainable development of materials: Broadening stakeholder engagement

We present a transformative vision for future materials selection, processing, and design decisions in the context of sustainability. Specifically, we highlight the concept of sustainable development of materials and the need to broaden the range of stakeholders engaged in materials design decisions. For instance, beyond the traditional structure–processing–performance triangle, there is a critical need to incorporate sustainability metrics into materials design. Such metrics embrace concepts of green chemistry and chemicals management, critical materials and materials circularity, materials substitution and alternatives assessment. Implementation requires broad engagement beyond the traditional materials science and engineering boundaries, including global perspectives on public policy, governance, economics, and public health. Educational norms clearly must also change, together with workforce development programs and comprehensive industrial buy-in. This vision is further expanded upon in the articles in this issue, which we summarize here, providing highlights of each article and identifying critical intersections among the topics presented, thereby providing a framework to realize our vision.


Sustainable development of materials: Broadening stakeholder engagement
Julie M. Schoenung* and Elsa A. Olivetti,* Guest Editors We present a transformative vision for future materials selection, processing, and design decisions in the context of sustainability. Specifically, we highlight the concept of sustainable development of materials and the need to broaden the range of stakeholders engaged in materials design decisions. For instance, beyond the traditional structure-processingperformance triangle, there is a critical need to incorporate sustainability metrics into materials design. Such metrics embrace concepts of green chemistry and chemicals management, critical materials and materials circularity, materials substitution and alternatives assessment. Implementation requires broad engagement beyond the traditional materials science and engineering boundaries, including global perspectives on public policy, governance, economics, and public health. Educational norms clearly must also change, together with workforce development programs and comprehensive industrial buy-in. This vision is further expanded upon in the articles in this issue, which we summarize here, providing highlights of each article and identifying critical intersections among the topics presented, thereby providing a framework to realize our vision.

Sustainable development of materials
Materials science and engineering is broadly considered to be an enabling technology, providing the foundation upon which other technologies advance. Developments in materials have provided the foundation for entire historical time periods, including the Stone Age, the Iron Age, the Bronze Age, and the Silicon Age. With each evolution in materials science has come extensive expansion of broad technological advances that enhance the human experience and economic growth and prosperity. Many advances in materials have also provided the foundation needed to develop technologies that address sustainability goals such as reduced carbon footprint as a strategy to mitigate climate change. For instance, advances in materials science have been essential to the development of renewable energy systems for technologies such as photovoltaic solar cells, wind turbines, and energy-storage batteries. Materials science also has enabled the development of electric vehicle technologies and energy-efficient light bulbs such as those that use light-emitting diodes (LEDs). These materialenabled advances in technologies are valuable and essential to saving our planet.
If we look a little closer, however, we note that the implementation of these technologies and utilization of these materials often result in undesirable impacts on humanity, society, and the planet. For instance, electric vehicles require substantially more materials than conventional combustion engines, estimated to currently be in the range of 20-30% heavier, primarily due to the weight of the battery pack. 1,2 Likewise, LED light bulbs are also far more material-intensive than conventional incandescent bulbs, weighing up to six times as much. 3 This increase in material mass, alone, can correlate to other negative consequences, such as more damage to roads and increased maintenance costs. 1,3 Moreover, increased material mass corresponds also to an increase in embodied energy, defined here as the energy required to extract, refine, process, or synthesize the raw materials. Furthermore, at end of use, more mass is discarded.
Beyond material mass considerations, the complexity of advanced technology products and the materials of which they are made is rapidly increasing. For instance, whereas electronic products manufactured in the 1990s consisted of roughly 30 elements, current electronic products require more than 70 elements for manufacture. [4][5][6] Also, alloys continue to become more and more complex, such as through developments in high-entropy alloys and ceramics, which can contain five to ten elements in equimolar ratios. [7][8][9] This increased complexity makes the task of materials recovery increasingly complex, costly, and wasteful, resulting in undesirable impacts on the environment, humans, and the planet. 10 The situation becomes even more complex in cases where the materials in products are chemically toxic. In such cases, even if efforts are made to recycle and recover the constituent materials, the toxic components must either be isolated along the way, or they continue to cycle through into new materials and products. An additional dimension that needs to be mentioned here is materials supply and availability. Various elements currently designed into advanced engineering technologies, such as cobalt, nickel, lithium, neodymium, dysprosium, rhenium, tantalum, platinum, and palladium, among others, are considered "critical" and are mined only in select locations around the globe, presenting not only potential supply risk concerns but also international inequities within the broad materials supply domain. 11 These challenges and often unintended undesirable consequences of materials selection and processing choices are extremely complex and require a broad range of approaches to resolve. We refer to this need to make such choices in an informed and intentional manner as "sustainable development of materials." This concept is presented schematically in Figure 1 and is the focus of this issue.
Efforts to address the sustainable development of materials have increased significantly in recent years, with increasing legislative and regulatory pressures and public relations and marketing strategies, facilitated by expanded tools and data sets to guide informed decision-making. Several of these efforts are described in the articles in this issue.
For proper context, we provide some additional background here. In the materials science and engineering community, the primary goal in materials development is to enhance performance, relative to a specific function. Such achievements are key to enabling new and advanced technologies. Consequently, it is common for materials experts to focus on what we refer to as the product manufacturing and product use stages of the life cycle, often neglecting the upstream (materials extraction and synthesis) stages and downstream (end-of-use/life disposal/recovery) stages. Yet the entire life cycle needs to be considered to avoid many of the unintended undesirable outcomes previously mentioned. This approach is generically referred to as life-cycle thinking. 12 Key to this broader perspective is to consider the raw material sources, which include naturally occurring, nonrenewable mineral/ore deposits for metals and inorganic materials such as ceramics and glass, and naturally occurring, nonrenewable fossil-fuel derived petroleumbased synthetic chemicals and products such as plastics and polymers. Alternatives to the latter include renewable sources such as plants to create bio-based organics, but there are no renewable alternatives for sourcing metals, ceramics, or glass.
The useful life of these materials can be extended through reuse, recycling, and recovery strategies, commonly referred to as implementing a "circular economy." Notably, these strategies also require input resources, including energy, water, and materials, and frequently generate undesirable outcomes, including waste and hazardous emissions (e.g., acids used for leaching and dust generated during size reduction). There is no free lunch. Yet, there is reason for hope and optimism. With increased attention to the sustainable development of materials, new strategies are constantly being developed, methods for using substitute materials or novel product designs are being implemented, and the materials community is becoming increasingly aware of the challenges and opportunities we face. Thus, we envision this issue of MRS Bulletin as a call to action for next-generation materials selection and process design to be viewed through the lens of sustainability. Figure 1. Schematic describing the concept of "sustainable development of materials." Incorporated into the concept are the intersecting principles of "safer chemicals" (promoting the use of safer chemicals to reduce toxicity, hazard, and consequential negative human health and environmental impact); "circular economy" (enabling a circular economy to reduce waste and depletion of naturally occurring material resources); and "energy efficiency" (motivating the selection of manufacturing process and materials that reduce carbon footprint and consequential impact on climate change). This concept is further enabled through the engagement of stakeholders, availability of proper data sets, and assessment tools, to facilitate informed decision-making.

Intersecting approaches to broaden stakeholder engagement
The key themes we see highlighted in the contributions within this issue reflect the challenges of researching, educating, and implementing systems thinking for sustainable development of materials. Each article conveys the importance of comprehensive quantification of the impact of materials and manufacturing, but asserts that this accounting lags novel materials development by decades on average, making predictive, comprehensive approaches particularly important. The contributing authors highlight the need to understand the impact of alternatives, increase transparency in our supply chains and manufacturing processes, and identifying mechanisms to support productive incentives toward improvements in sustainability. We see described across these features examples drawn from chemicals alternatives assessment, semiconductor production, and electronic waste recovery that explain how solutions will each require deep stakeholder engagement. Even though the authors come from a range of disciplines, they reflect common themes in sustainable sourcing, managing environmentally persistent chemicals and pollutants, managing quality of recycled materials at every stage of development, and deployment and learning from recent discoveries and the more distant past. The differences are also informative: the categories, terminology, and analogies these authors use and draw from reflect varying perspectives on how boundaries are drawn, which have implications for ownership and solution development. These authors paint a stark picture. There is a great challenge for material scientists and engineers in attempting sustainable development of materials. Each contribution, however, provides steps forward and opportunities to continue learning and creating thoughtfully within the discipline. First, Ogunseitan 13 asserts in his article that the metrics we use to evaluate the sustainability of a material must be broadened beyond chemical sourcing (production and manufacturing) to also include chemical usage and pollution, in particular toward comparative hazard and exposure assessment. The challenges are multitudinous and the impact on human FoS Subcommittee have targeted the incorporation of sustainability topics into materials science curricula. Also, the long-standing panel discussion series, Materials Needs for Energy Sustainability by 2050, established by the MRS FoS Subcommittee and coorganized with the MRS Energy & Sustainability journal, convenes top experts at each MRS Meeting to discuss scientific, technological and sociological complexities relating to energy, sustainability, and the environment. Recent panels have focused on circular economies, cleaner energy sources, long-duration energy storage, and climate change.
Shifting materials scientists' perceptions of and approaches to sustainable development of materials will take a concerted effort that builds over time. In the near term, the MRS Focus on Sustainability Subcommittee will continue programming at MRS meetings and in-between, and will coordinate with publications that put the materials-sustainability nexus in the spotlight. This special issue of MRS Bulletin, with a focus on sustainable development of materials, is one of these efforts.
In the long term, the efforts aim to encourage students and young researchers, faculty, and industry representatives to see sustainable development of materials as a defining challenge of our time and as a context in which materials research broadly should be framed.
The sustainable development of materials requires the systematic reduction of resource inputs and the mitigation of environmental and human health impacts across all stages of the materials life cycle. At the same time, materials play a pivotal role in achieving sustainable development, from producing clean energy and providing access to clean water to sequestering carbon and ensuring a dependable supply of raw and recycled materials for infrastructure, devices, and consumables.
Meeting these challenges and realizing these opportunities requires an integrated approach that brings other scientific disciplines to bear and places materials science in the context of societal, environmental, and economic drivers. Recognizing the complexity of tackling sustainable development issues and the importance of materials to enabling solutions, the Materials Research Society (MRS) created the Focus on Sustainability (FoS) Subcommittee, a part of the Society Agility Council.
Since 2016, the MRS FoS Subcommittee's dedicated efforts to build a robust community of practice around materials and sustainability have led to a number of highly successful events and activities. Technical and broader impacts symposia and tutorials have brought researchers from materials science and related disciplines together to share their work. Professional development seminars and workshops and hands-on activities have introduced MRS members to new information and frameworks for improving the sustainable development of materials. Other efforts by the MRS health is startling and broad, given the continuous examples across geographies and time where humans have exceeded the scientifically grounded safe operating space for chemicals. Ogunseitan describes motivating forces where opportunities to shift our approach to chemicals design could arise through regulation, non-governmental and manufacturer-driven initiatives, and all the way to consumer preferences that influence marketing strategy and public image. There is a need to evaluate which of the strategies for alternative chemicals design and management work best to solve different problems and at a much faster pace so that these assessments could be done before chemicals go to market. We must accelerate assessment so that the problems get solved faster, and earlier in the design process, rather than when products become waste.
Ogunseitan 13 also highlights the need for data to guide decisions, that transparency is imperative for accountability and to allow for any assessments to be truly useful. These concepts should be linked more deeply to the high-throughput materials design concepts centered within the Materials Genome Initiative and focus efforts on including resource use and emissions information within machine learning-ready data. 14,15 Most provocatively, Ogunseitan maintains that the sound management of chemicals will only come when impact forecasting tools are also considered within a planetary boundary framework. What does this look like specifically? We could find interim strategies that engage communities in the pursuit of knowledge through early warning systems when new chemicals are introduced that then link local impact to supply chain implications and eventually toward global impact. This must be done while providing prospective information across the entire life cycle and directly contributing to forming regulatory practice and reforming manufacturing procedures.
Sahajwalla and Hossain 16 present a contribution on recovery for long-lived products at end of life and motivate inquiry into a product-centric approach to sustainable development of materials. This is juxtaposed by short-lived products where a more materials-centric approach provides opportunity as well; both strategies require consideration of rebound when accounting for any environmental benefit. 17 These themes are aligned with the pioneering efforts of Reuter et al. and focus on the oft desired combination of design and recovery methods pointing to needs for modularity, substitutability, and selective extraction or synthesis of metals. 18 Through a design-centered grounding of the circular economy, Sahajwalla and Hossain 16 push the community of materials scientists and engineers to think more robustly about the materials we develop and design into products. Providing a deep dive into the chemical composition of longer-lived products, including electronics, energystorage units, and solar panels, the authors offer a baseline from which to consider recovery innovation. These authors also furnish a review of the prevailing recovery technologies to set the stage for transformative recycling and reuse strategies. They reference challenges such as materials complexity and mixing (across organic and inorganic species), which increases the number of post-processing steps as well as tradeoffs across processes that are dependent on temperature-based separation or chemical-based separation. They explain that these tradeoffs will change depending on chemical composition and the form in which the material is used within the final product as well as the location or system architecture that could be pursued.
This article by Sahajwalla and Hossain 16 further motivates the charge offered by Ogunseitan 13 given the potential for chemical leakage once electronics are put in service and after end of life. Sahajwalla and Hossain 16 also echo themes from Ogunseitan 13 to consider the nature of chemicals used and the function they provide within the design process. Similarly pointing to legislative opportunity, we must continue to focus on ways to drive source separation through policy, including Extended Producer Responsibility and seek modularity in design and processing so that recovery processes can be used in a focused way. 19,20 By capturing opportunities for the materials community in synthesis, production, and use of chemicals all the way to recovery processes at end of life, these first two contributions in the issue provide examples of the extent of the challenge we face.
Formulating lessons toward solution implementation, Anderson et al. 21 in their article in this issue provide integrated corporate accounts of how opportunity arises for shifts toward more sustainable development of materials. In particular, they focus on primary examples when supply chain disruptions limit availability for incumbent materials. In crisis situations, doors could open to shift away from ossified, conventional approaches to alternatives that would have difficulty overcoming institutional barriers otherwise. The utilization of these alternative materials can persist even after the crises are averted. Anderson and colleagues provide evidence that even when there is not direct market pull, we must be ready as a research community with robust, tested alternatives. In this specific example, disruptions were caused by the contracted economic impact of the pandemic with subsequent rapid economic expansion. More broadly, options for managing the disruptions included stopping production, sourcing small quantities, or substituting, or seeking alternatives; each of these options follows the implementation strategies of industrial ecology framing. 22 Anderson et al. 21 describe the specific case of postindustrial polyamides derived from automotive airbags and carpet, where consistency of feedstock determined suitability, and fiberglass replacement by basalt fiber, where the concern was the ability to scale the supply chain for this nascent material sufficiently to meet demand. The authors highlight that an expert workforce with depth in their technical understanding enabled ready access to the most vital information. This meant that the risk of alternative materials use was mitigated, in part, based on well-trained practitioners, which surgically focused time and resources. As a first step, we can use this example to codify best practices that could make it replicable, including ready access to technical expertise.
The example provided by Anderson et al. 21 is reinforced by Handwerker's article 23 with a call to action around education and workforce development. In order for sustainable development of materials to be implemented, we must transform the way MRS BULLETIN • VOLUME 48 • APRIL 2023 • mrs.org/bulletin we educate the workforce to know, not only what to do, but also how to build capacity in order to execute. In her contribution, Handwerker emphasizes that we will not be able to solve these problems and create innovative solutions if materials scientists and engineers lack an appreciation of the complexity of the issue and are insufficiently multilingual across disciplines, fluent in the language associated with the potential solutions (in both knowledge and action). Getting people to even consider these metrics in their materials selection and design decisions requires partnerships and fundamental restructuring of curriculum. We need to train individuals who cross bridges of the disciplines (Handwerker provides an example within environmental engineering and in electronics), and can therefore create solutions from a higher level to define visionary strategies rather than only incremental ones. This broad training generates a community of practice, moving from linear modes of education in sustainability that provide little systematic training to students who can think across, for example, electronics design and waste management. Then solutions to supply chain disruption or materials recovery will bridge materials classes more effectively and derive from use cases all the way from longlived infrastructure within the built environment to short lifetimes within consumer products. The community has begun to arrive at themes to build sustainability literacy across science and engineers, including, first and foremost, leadership skills that enable work across boundaries (discipline and culture), which have the potential to empower others toward technically feasible and morally just solutions. Handwerker provides a framework of how we could build stronger links and build bilingual thought leaders between techno-centric and ecology-centric concepts. Consistent with Handwerker's comments on materials programs, 23 a recent editorial in the Journal for Engineering Education 24 conveys that we must also revamp our broader engineering training given the increasing volatility and vulnerability in our natural ecosystems and supply chains. Emerging practitioners must, for instance, specifically know how to link the implications of climate change to engineering design. Functionality and performance will change as local weather events become more extreme and as water tables change, which necessitates integrated knowledge sharing across climate scientists and hydrologists, for example. Not only will these efforts require links across science and engineering, they must incorporate a wider range of disciplines into engineering solutions, including ecologists, toxicologists, and epidemiologists, as chemical pollution (see the article by Ogunseitan 13 for further evidence of this link), and habitat degradation exacerbate climate impacts on certain ecosystem services. Each of these systems: biological, sociotechnical, and ecological processes are highly complex. The often reductionist approach to engineering education underestimates the sensitivity of ecosystems that will be further complicated by climate impact. 25 The only path forward includes deep commitment to the ethics and justice of engineering, constantly probing whether relevant local stakeholders can engage in system design to help balance benefits and impacts. This requires skill development to listen and collaborate with diverse communities, which can be achieved by ensuring representation within the discipline as well as awareness of embedded community knowledge in order to design decisions that will last decades. In her article, Handwerker 23 points to new opportunities for funding via recent initiatives to build strong curricula and professional workforce development opportunities that are linked to industry. Motivated by real-world challenges in sustainable development of materials in industry, as also described by Anderson et al., 21 we can cultivate interest among students who desire to become the needed agents of change.
Finally, Mavhunga 26 inspires our community to consider the broader implications on the use of materials linked to the geographic, political, and social value chains that these supply chains are inextricably linked to. He highlights vivid examples of the significant disruption, destruction, and decimation caused by mining critical raw materials, particularly in Africa. Mavhunga traces back from slave trade, colonialism, and plantation systems of extractive infrastructure within the African continent to current case studies in extraction of chromium, cobalt, and lithium. The vision and transformation he describes conveys the opportunity to shift these supply chains away from extractivism toward value addition to domestic communities in these regions. He provides a sense of the ingredients needed to undertake this transition, including energy production, particularly around stabilizing energy supply by developing independent power infrastructure around production and manufacturing centers. Equally important elements are to build stronger financial mechanisms that treat infrastructure as an investment class, and also to improve local markets and train a technical workforce. Historically this local value addition has been hindered by market dynamics and external competition. Through examples, Mavhunga identifies previous declines based on shifts in energy sources, local depletion of talent, and unfavorable economic and legislative practices. Through the emerging African Continental Free Trade area, and the role of Chinese investment in Africa, there is opportunity at present to create intra-Africa value addition by consolidating efforts, both in finance and negotiating power, to increase leverage and shift the paradigm. These are transformative first steps in data sovereignty and empowering local communities with information access through effective governance. 27 By viewing the alternatives assessment ideas brought by Ogunseitan 13 or the recovery practices offered by Sahajwalla and Hossain 16 through the lens that Mavhunga 26 shares, we are inspired as materials industrial ecologists to think not just about the life-cycle implications, but also the entire global context of materials given the links between materials location, transportation, energy, equipment, and skill.
to A.D. Dupuy for technical discussions and assistance with preparing Figure 1.

Conflict of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.

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