Lifecycle analysis of nanotechnology-enhanced soft materials in the circular economy

Abstract

Nanotechnology-enhanced soft materials, ranging from polymers and gels to bio-based composites, offer improved functionality and durability across diverse sectors. As their use grows, assessing their environmental sustainability within the circular economy framework is critical. This study applies life cycle assessment (LCA) to evaluate the environmental impacts of these materials across production, use, and end-of-life stages. Findings reveal that while nanomaterials often incur high production impacts, especially in energy use and toxicity, their enhanced performance can offset these burdens during use. Green synthesis, renewable energy, and design-for-environment strategies show promise in reducing lifecycle impacts. This is the first conceptual review that systematically maps nanomaterial design features, such as synthesis routes, surface properties, and morphologies, to environmental performance metrics including energy use, toxicity, and end-of-life behavior. This study uniquely integrates a keyword co-occurrence analysis using the PRISMA methodology to identify thematic research clusters and underexplored intersections between nanotechnology, life cycle analysis, and circular economy. The network and density visualization maps provide further critical insights into the existing knowledge paving the path towards identification of underexplored keywords. By combining bibliometric analysis with design-performance mapping, this work pioneers a novel framework to guide future interdisciplinary research and sustainability assessments in the field. However, methodological gaps in LCA, such as the lack of nano-specific data and characterization factors, hinder comprehensive assessment. The study emphasizes the need for improved LCA models, stakeholder collaboration, and innovation management to support the sustainable integration of nanotechnology in circular value chains.

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Design, System, Application

This study applies life cycle assessment (LCA) to evaluate the environmental impacts of these materials across production, use, and end-of-life stages. Findings reveal that while nanomaterials often incur high production impacts, especially in energy use and toxicity, their enhanced performance can offset these burdens during use. Green synthesis, renewable energy, and design-for-environment strategies show promise in reducing lifecycle impacts.

1 Introduction

The integration of nanotechnology into soft materials has led to a new class of high-performance materials with enhanced mechanical, thermal, and functional properties.¹ These nanotechnology-enhanced soft materials, which include polymers, gels, elastomers, and bio-based composites infused with nanoscale additives such as nanocellulose, graphene, carbon nanotubes (CNTs), and nanoclays, are increasingly being utilized across diverse sectors, including packaging,^2,3 biomedical devices, flexible electronics, coatings, and sustainable automotive parts.⁴ Their enhanced properties offer significant potential for reducing material usage, improving product durability, and enabling new functionalities that align with sustainability goals.^5,6

As the global shift toward a circular economy (CE) gains momentum, there is a growing need to evaluate not just the performance, but the entire life cycle impacts of these advanced materials.^7–9 The circular economy emphasizes waste minimization, resource efficiency, and closed-loop material flows, which contrasts with traditional linear “take-make-dispose” models. However, integrating nanotechnology-enhanced soft materials into circular systems presents unique challenges and opportunities, particularly due to the complexity of their material compositions, uncertain end-of-life pathways, and the lack of standardized recycling technologies for nanomaterials.^10,11

Therefore, life cycle assessment (LCA) serves as a comprehensive and essential tool for understanding the potential environmental impacts associated with nanotechnology-enhanced soft materials.^12,13 LCA adopts a holistic approach to evaluate a product's environmental footprint across its entire life cycle—from raw material extraction and manufacturing to use and end-of-life disposal.^14–16 This includes analyzing material and energy inputs, as well as emissions released into the environment. Such an approach is particularly critical for assessing the potential implications of nanomaterial releases into ecosystems, as illustrated in Fig. 1.¹⁷

Fig. 1 A generic life cycle assessment framework. Reprinted from ref. 17 with permission from MDPI, copyright 2021.

LCA is governed by internationally recognized standards established by the International Organization for Standardization (ISO 14040 series, 2006), and it is structured into four key phases: (i) goal and scope definition, (ii) life cycle inventory analysis (LCI), (iii) life cycle impact assessment (LCIA), and (iv) life cycle interpretation.¹⁷ Originally developed to quantify and reduce environmental burdens of products and processes, this methodology has become increasingly relevant for emerging technologies, including those involving nanomaterials, as it enables a systems-level evaluation of sustainability across all stages of a product's life cycle.¹⁸

This study aims to critically explore the life cycle implications of nanotechnology-enhanced soft materials within the framework of the circular economy. It will assess the environmental performance, recyclability, and system-level sustainability of nanotechnology-enhanced soft materials, while addressing the methodological gaps in existing LCA approaches when applied to emerging nanotechnologies.

2 Lifecycle stages of nanotechnology-enhanced soft materials

The lifecycle of nanotechnology-enhanced soft materials encompasses four primary stages: material production, product design, usage phase, and end-of-life management. Each stage presents unique opportunities for innovation and sustainability, as well as challenges that must be addressed to ensure environmental and human safety.

2.1 Material production and nanofabrication

The production of nanotechnology-enhanced soft materials is the first stage in their lifecycle. This stage involves the synthesis of nanomaterials, their functionalization, and their integration into the final product. The environmental and health impacts of this stage are significant, as the synthesis of nanomaterials often requires high energy inputs and can generate hazardous byproducts.

Synthesis and functionalization. The synthesis of nanomaterials can be achieved through various methods, including chemical synthesis, physical synthesis, and biological synthesis. Each method has its environmental implications. For example, chemical synthesis often involves the use of toxic chemicals and solvents, which can pose risks to both human health and the environment.^19,20 Functionalization, the process of modifying nanomaterials to enhance their properties, can further complicate the environmental profile of these materials.¹⁹

Table 1 summarizes various studies highlighting the synthesis methods used for nanomaterials, emphasizing energy demands, process efficiency, environmental considerations (carbon emissions, ecotoxicity), and overall production impacts.

Table 1 Comparative analysis of nanomaterial synthesis methods based on energy requirements, efficiency, environmental and production impacts

Study	Synthesis method	Energy requirements (GJ kg^−1)	Process efficiency	Key factors	Carbon emissions	Ecotoxicity impact	Production impact
Christé et al., 2020 (ref. 21)	Microwave-assisted hydrothermal and solvothermal	No mention found	Hydrothermal more efficient	Microwave irradiation (700 W for 10 minutes)	No mention found	No mention found	Hydrothermal with ethylenediamine (EDA) lowest impact
Eckelman et al., 2012 (ref. 22)	Arc ablation, chemical vapor deposition (CVD), high pressure carbon monoxide (HiPco)	1–900 GJ kg^−1	No mention found	Electricity consumption	No mention found	Significant	Exceeds direct exposure impacts
Gao et al., 2013 (ref. 23)	No mention found	No mention found	No mention found	Recycling chemicals, up-scaling production	High CO2 burden	No mention found	Significant, affected by recycling and scaling
Kim and Fthenakis, 2013 (ref. 24)	Various	1–900 GJ kg^−1 for carbon-based nanoparticles	No mention found	Energy-intensive synthesis process	Higher cradle-to-gate impact	No mention found	Higher than conventional materials
Martins et al., 2017 (ref. 25)	Traditional and green synthesis	No mention found	Green synthesis more efficient	Electricity production	Lower for green synthesis	No mention found	Green synthesis 50% lower impact
Melo et al., 2023 (ref. 96)	Double emulsion and nanoprecipitation	No mention found	Nanoprecipitation more efficient	Electricity consumption	No mention found	Freshwater ecotoxicity significant	Nanoprecipitation 61% lower impact than double emulsion
Pini et al., 2015 (ref. 26)	Bottom-up hydrolytic sol–gel	No mention found	No mention found	Energy consumption significant	No mention found	No mention found	Significant impact from precursor
Pourzahedi and Eckelman, 2015 (ref. 27)	Chemical reduction, physical methods	No mention found	Chemical reduction generally preferred	Heating energy requirements	No mention found	Significant, varies by method	Dominant for nearly every category
Rosa et al., 2023 (ref. 28)	Solution combustion synthesis (SCS), hydrolytic sol–gel synthesis (HSGS), non-hydrolytic sol–gel synthesis (NHSGS)	No mention found	SCS more efficient	Heating requirements	Lowest for SCS	Considered in assessment	SCS lowest overall impact
Tsang et al., 2018 (ref. 29)	Supercritical fluid flow, conventional precipitation	No mention found	Supercritical fluid flow more efficient	Moderate temperature requirements

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Several studies have investigated the environmental impacts of different synthesis methods for nano-enhanced soft materials, highlighting significant findings and trade-offs. Martins et al. (2017)²⁵ revealed that their green synthesis approach for nano-scale zero valent iron resulted in approximately 50% lower environmental impact compared to traditional methods. This underscores the potential of green synthesis to reduce resource consumption and environmental burden. Similarly, Rosa et al. (2023)²⁸ noted that solution combustion synthesis (SCS), considered environmentally friendlier, exhibited lower impacts than hydrolytic and non-hydrolytic sol–gel synthesis methods in producing TiO₂ nanoparticles. Their findings emphasize the importance of considering synthesis techniques that minimize environmental footprints. In contrast, Christé et al. (2020)²¹ demonstrated that a hydrothermal synthesis route using ethylenediamine (EDA) was more sustainable than solvothermal methods for producing N-doped carbon dots, highlighting the benefits of specific green methods tailored to different materials. However, Pourzahedi and Eckelman (2015)²⁷ cautioned about trade-offs in bio-based chemical reduction methods for silver nanoparticles, noting potential issues such as ozone depletion and ecotoxicity. This comprehensive review underscores the complexity of balancing environmental considerations with technological advancements in nano-material synthesis.

The Table 2 systematically maps key nanomaterial design features, including synthesis methods, surface properties, and morphological characteristics, to relevant environmental performance metrics such as energy requirements, toxicity, environmental fate, and end-of-life behavior. By integrating data from multiple studies, it highlights how molecular-level decisions influence sustainability outcomes across the nanomaterial life cycle.

Table 2 Mapping of nanomaterial design features to environmental performance metrics across lifecycle stages

Study	Synthesis method	Surface properties	Morphology	Energy use	Toxicity/health impact	Environmental fate	End-of-life/recyclability
Pourzahedi & Eckelman (2015)^27	Chemical reduction, flame spray pyrolysis, arc plasma	Capping agents (e.g., trisodium citrate)	Spherical (100 nm AgNPs)	27.8 kW h kg^−1 AgNP	Size-dependent LC50 (zebrafish); surface chemistry matters	Not reported	Not reported
Buchman et al. (2019)^30	Not specified	Negative surface charge, PEG ligands, antioxidants	Not reported	Not reported	High toxicity via ROS, cell surface damage, ion dissolution	Not reported	Not reported
Wu et al. (2019)^31	Physical, chemical, biological	Not reported	Not reported	Physical & biological routes more energy-intensive	Titanium dioxide nanoparticles (TiO2NPs) exhibit varying degrees of toxicity depending on the synthesis route (physical, chemical, or biological), concentration, size, and other physicochemical properties	Not reported	Not reported
Olapiriyakul and Caudill (2009)^32	Not specified	Not reported	Not reported	Recycling demands significant energy due to the distinct melting points and specific heat characteristics of nanomaterials	Nanotechnology products are crucial due to potential toxicity and health impacts, as nanomaterials can behave differently from their bulk counterparts and may pose risks to humans and the environment	Products developed through nanotechnology pose notable environmental concerns due to the possibility of nanomaterials being released and their effects on ecosystems. The long-term fate and potential toxicity of nanomaterials after product disposal are not fully understood, necessitating careful consideration of environmental impacts	High exergy loss, low recovery potential
Harper et al. (2011)^33	Phosphine-stabilized gold nanoparticle synthesis, introduce surface functionalities to gold nanoparticles via ligand exchange methods	The particles behaved differently depending on surface charge	Spherical (0.8–15 nm AuNPs)	Not reported	The embryonic zebrafish assay demonstrated that gold nanoparticles lacking any charge do not negatively affect biological systems over a wide range of sizes. In contrast, AuNPs with either positive or negative charges significantly disrupted development, with positively charged AuNPs mainly leading to mortality and negatively charged ones causing malformations	Not reported	Not reported
Eckelman et al. (2012)^22	Arc ablation, CVD, HiPCO	Not reported	Not reported	Electricity generation dominates impacts	Ecotoxicity from electricity-related emissions	Not reported	Not reported
Nel et al. (2013)^34	Flame spray pyrolysis (ZnO)	Surface coating with cysteine could reduce the surface reactivity, with a reduction in cellular as well as embryo toxicity	Nanospheres (ZnO), rod-like (MWCNTs)	Not reported	The dissolution of ZnO nanoparticles results in the release of toxic Zn^2+, which can produce reactive oxygen species (ROS). When ZnO is doped with iron, there is a notable decrease in cytotoxicity as the atomic percentage of iron increases	Iron-doping improves stability; less dissolution	Reduced environmental risk via lower dissolution
Tsang et al. (2018)^29	Supercritical fluid flow synthesis of TiO2	Not reported	Spherical, well-crystallized particles without any amorphous portions	Cumulative energy demand 78 MJ kg^−1 TiO2	Occupational indoor air emissions of nano-TiO2 were responsible for 5% of the non-carcinogenic human toxicity	Impact reductions ranged between low of 17% for urban land occupation to a high of 99% for marine eutrophication	Not reported

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Energy and resource use. The production of nanomaterials is often energy intensive. Studies have shown that the use of renewable energy sources, such as wind and solar power, can significantly reduce the environmental footprint of nanomaterial production.^35,36 Additionally, the use of biogas and other sustainable energy sources can further mitigate the environmental impacts of this stage.³⁵

Process optimization and efficiency play a crucial role in reducing the environmental impact and enhancing the sustainability of nano-material synthesis. Several studies have shown that optimizing synthesis parameters, selecting appropriate processes, and integrating innovative technologies can lead to substantial improvements. Gao et al. (2013)²³ emphasized that recycling chemicals and scaling up production significantly influence the environmental footprint, particularly in the synthesis of hollow silica nanospheres. In terms of alternative energy sources, Christé et al. (2020)²¹ demonstrated that microwave-assisted synthesis enabled rapid heating and potentially reduced overall energy consumption, offering a more efficient route for producing N-doped carbon dots. Similarly, Tsang et al. (2018)²⁹ reported that supercritical fluid flow synthesis, which operates at moderate temperatures, could be a more energy-efficient and environmentally friendly alternative to conventional precipitation methods for TiO₂ nanoparticles. Furthermore, process selection is critical, as shown by Melo et al. (2023),³⁷ who found that the nanoprecipitation method had a 61% lower total environmental impact compared to the double emulsion process for fabricating nano-enabled pesticides. These findings collectively highlight the importance of optimizing synthesis routes to improve both efficiency and sustainability in nanomaterial production.

The release of nanomaterials into the environment during production can have unintended consequences. Research has highlighted the importance of implementing emission control measures to minimize the environmental and health risks associated with nanomaterial production.^20,38

2.2 Product design and functionality

The design phase is critical in determining the environmental and health impacts of nanotechnology-enhanced soft materials. This stage involves the selection of materials, the design of the product, and the consideration of its intended use.

The choice of nanomaterials and their properties can significantly influence the environmental performance of the final product. For example, the use of biodegradable nanomaterials can reduce the environmental impacts associated with the end-of-life stage.³⁹ Additionally, the use of nanomaterials that can be easily recycled can enhance the sustainability of the product.⁴⁰

The concept of “Design for Environment” (DFE) has gained prominence in recent years. This approach emphasizes the need to consider environmental and health impacts at the design stage. For example, the design of products with recyclability and reusability in mind can significantly reduce their environmental footprint.⁴¹

LCA is a powerful tool for evaluating the environmental impacts of nanotechnology-enhanced soft materials at the design stage. By conducting an LCA, designers can identify the stages in the product lifecycle that have the highest environmental impacts and develop strategies to mitigate these impacts.⁴⁰

The environmental assessment of nano-enhanced soft materials requires a comprehensive life cycle perspective, as highlighted by several key studies. Kim and Fthenakis (2013)²⁴ found that while nanomaterials generally exhibit higher cradle-to-gate energy demands and global warming potentials compared to conventional materials, their cradle-to-grave impacts can be lower when considering improved performance in end-use applications, such as energy-efficient devices. Similarly, Eckelman et al. (2012)²² reported that for carbon nanotubes, the environmental impacts associated with production outweighed those from direct exposure, particularly in terms of ecotoxicity. Pourzahedi and Eckelman (2015)²⁷ further emphasized the dominance of upstream production impacts, such as the extraction and processing of silver, in nearly every environmental impact category (ozone depletion, global warming, photochemical smog, acidification, and eutrophication) associated with silver nanoparticle synthesis. Additionally, their findings revealed that adjusting results based on the functional unit (the defined reference unit for comparing systems, such as antimicrobial efficacy per gram of nanosilver), such as size-dependent antimicrobial efficacy, could significantly alter the preferred synthesis method in each impact category (environmental impact categories, human health: carcinogens, human health: non-carcinogens, human health: criteria air pollutants, ecotoxicity fossil fuel depletion). These studies collectively highlight the complexity of evaluating the sustainability of nanomaterials and reinforce the importance of adopting cradle-to-grave life cycle assessments that account for both environmental burdens during production and potential benefits throughout the product's lifespan.

2.3 Usage phase and performance benefits

The usage phase is where the nanotechnology-enhanced soft material is put into service. This stage is critical in determining the actual environmental and health impacts of the material, as it is during this phase that the material is exposed to various environmental conditions and user interactions.

The performance and durability of nanotechnology-enhanced soft materials can significantly influence their environmental impacts. For example, materials that have a longer lifespan can reduce the need for frequent replacements, thereby reducing the overall environmental footprint.⁴² Additionally, materials that are more resistant to degradation can reduce the release of nanomaterials into the environment during use.³⁸

The release of nanomaterials during the usage phase can have unintended environmental and health consequences. Research has shown that the release of nanomaterials can occur through various mechanisms, including wear and tear, leaching, and degradation.^38,43 The extent of release depends on the properties of the nanomaterials and the conditions under which they are used.

The safety of users during the usage phase is a critical consideration. Nanotechnology-enhanced soft materials can pose risks to human health if they are not properly designed and tested. For example, the release of nanomaterials from textiles and other consumer products can lead to exposure through skin contact or inhalation.⁴³

2.4 End-of-life management and environmental impact

The end-of-life (EOL) stage is the final phase in the lifecycle of nanotechnology-enhanced soft materials. This stage involves the disposal, recycling, or reuse of the material (Fig. 2). The EOL stage is critical in determining the overall environmental and health impacts of the material, as improper disposal can lead to the release of nanomaterials into the environment.

Fig. 2 End of life scenarios for nano-enhanced soft materials [created by the authors].

Recycling and reuse are critical strategies for reducing the environmental impacts of nanotechnology-enhanced soft materials. However, the recycling of nanomaterials is often challenging due to their small size and complex composition. Research has shown that the development of efficient recycling technologies is essential for improving the sustainability of nanotechnology-enhanced soft materials.^39,40

Landfilling and incineration are common disposal methods for nanotechnology-enhanced soft materials. However, these methods can lead to the release of nanomaterials into the environment, where they can persist for long periods and cause ecological harm.^38,44 The development of safer disposal methods is therefore critical for mitigating the environmental impacts of these materials.

The environmental fate and transport of nanomaterials during the EOL stage are influenced by various factors, including their physical and chemical properties, as well as the disposal methods used. Research has shown that nanomaterials can persist in the environment for long periods, where they can interact with biological systems and cause adverse effects.³⁸

3 Comparative life cycle assessment of traditional and nano-enhanced soft materials

3.1 Comparative performance: energy efficiency

The energy efficiency of nano-enhanced soft materials varies significantly depending on the type of nanomaterial and its application. A common observation across multiple studies is that the production phase of these materials is notably more energy-intensive compared to traditional soft materials. For instance, carbon nanofiber (CNF) polymer composites have been found to require between 1.3 and 12 times more energy than steel during production.^45,46 Similarly, nanosilver-based products, such as antimicrobial T-shirts, were shown to have a higher climate footprint than their conventional counterparts.⁴⁷

In contrast, nanoclay composites appear to be more energy efficient, with Joshi (2008)⁴⁸ reporting that their production consumes less energy than many traditional biopolymers and glass fibers. While high energy use during the production stage is a challenge, the use phase of certain nano-enhanced materials offers potential compensatory benefits. CNF composites, for example, have demonstrated improved fuel economy in automotive applications, potentially offsetting their initial production impacts.^45,46

Furthermore, consumer behavior plays a critical role in determining the lifecycle energy impact of nano-enabled products. Studies by Walser et al. (2011)⁴⁷ and Westerband and Hicks (2018)⁴⁹ emphasize that usage habits—such as the frequency and method of washing nanosilver garments—can dominate total energy consumption. Additionally, there is room for optimizing energy use during nanomaterial synthesis. Garcia Gonzalez et al. (2022)⁵⁰ identified high electricity demands in lab-scale nanomaterial development but noted that process optimization could significantly reduce environmental burdens. Thus, although nano-enhanced soft materials often start with higher energy costs, lifecycle savings may be achievable through intelligent design, efficient use, and improved consumer practices.

3.2 Environmental release and toxicity

Environmental release and toxicity represent major concerns when evaluating the overall sustainability of nano-enhanced soft materials. The production phase, particularly in nanosilver synthesis, can contribute significantly to environmental toxicity due to mining waste and high electricity consumption.⁵¹ These upstream impacts underscore the need for careful material selection and cleaner synthesis methods.

During the use phase, the potential release of nanomaterials is especially pronounced in consumer products. For example, Walser et al. (2011)⁴⁷ found that nanosilver T-shirts released up to 67% of their silver content through washing, raising concerns about aquatic toxicity. Similarly, Westerband and Hicks (2018)⁴⁹ observed nanosilver migration from food containers into stored items, though they deemed the overall environmental risk minimal. Such findings highlight the importance of understanding exposure routes and use-phase dynamics in assessing environmental safety.

At the end-of-life stage, disposal and degradation processes can introduce additional risks. Singh et al. (2017)⁵² reported that nano-enabled thermoplastics released higher concentrations of polycyclic aromatic hydrocarbons (PAHs) during thermal decomposition, increasing their cytotoxic potential. On the other hand, some nanomaterials show positive outcomes in biodegradability. Yasin et al. (2022)⁵³ noted that incorporating cellulose nanocrystals (CNCs) into rubber nanocomposites enhanced their biodegradation, potentially reducing long-term waste impact. Importantly, even at low concentrations, nanomaterials can disproportionately influence environmental toxicity, as emphasized by Carroccio et al. (2022)⁵⁴ and Pourzahedi and Eckelman (2015).⁵¹ This “low loading, high impact” characteristic necessitates thorough lifecycle evaluation of nanomaterial usage.

3.3 Material-specific considerations

Different nanomaterials exhibit unique environmental performance characteristics throughout their lifecycle. Carbon nanofibers (CNFs), while offering potential energy savings in use (e.g., lightweight automotive components), have high production energy demands and unresolved end-of-life challenges.^45,46 In contrast, nanosilver—though valued for its antimicrobial properties—presents significant ecological concerns, especially in marine environments, due to its propensity to leach during washing and disposal.⁴⁷

Table 3 compares the life cycle impacts of traditional and nano-enhanced soft materials, highlighting differences in environmental performance across categories such as energy use, emissions, and resource consumption. Nanoclays show promise as a relatively sustainable option, with Joshi (2008)⁴⁸ reporting lower energy use and greenhouse gas emissions during production compared to several traditional materials. However, their sustainability benefits are application-specific and can vary depending on the functional unit (a quantified description of the product system's function, serving as a reference point for all inputs and outputs) used in lifecycle analysis. Cellulose nanocrystals (CNCs) offer another interesting trade-off: they increase biodegradation potential, particularly in rubber-based composites, but also contribute to higher manufacturing impacts.⁵³ Meanwhile, nano-enabled thermoplastics may enhance mechanical properties, yet their disposal via incineration can release toxic byproducts such as PAHs, raising health and environmental concerns.⁵²

Table 3 Comparative life cycle assessment (LCA) of traditional vs. nano-enhanced soft materials

Lifecycle stage	Impact category^a	Traditional soft materials	Nano-enhanced soft materials	Key findings from studies
a ISO 14040 defines an impact category as a group of environmental concerns linked to life cycle inventory results.
Production	Energy use	Moderate to low	Often high (1.3–12× more than steel for CNF composites)	CNF, nanosilver, and CNC require high energy inputs^45,54
	GHG emissions	Moderate	Often high	Production dominated by electricity use and emissions^51
	Chemical use	Controlled/standardized	High (especially with silver & titanium dioxide)	High chemical use in nanoparticle synthesis^50
Use phase	Durability & Efficiency	Lower mechanical strength and lifespan	Higher strength and performance; potential energy savings	Fuel savings from CNF in automotive use; use-phase can offset production impact^46
	Release/toxicity	Generally inert	Risk of nanomaterial release during use	67% silver released from nanosilver T-shirts during washing^47
	Consumer behavior influence	Minor	Significant (washing, usage, exposure)	Energy/water use in consumer washing can dominate impact^49
End-of-life	Recyclability	Well-established methods	Complex, varies by material	CNC-enhanced rubber shows higher biodegradability; nanosilver contributes to toxicity^52,53
	Environmental fate	Predictable degradation	Potential for toxic leaching or PAH formation	Nano-enhanced plastics can release PAHs during decomposition^52
	Biodegradability	Often poor	Variable (improved with CNC, poor with CNF)	CNC increases biodegradation; silver and CNF are persistent^53
Overall life cycle	Environmental impact	Lower but with less performance	Depends on application, loading, and lifecycle phase	Trade-offs between high production impacts and use-phase benefits; impact varies by nanomaterial

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The system boundary for nanocellulose-reinforced epoxy composites and benchmark materials is shown schematically in Fig. 3.⁵⁵ According to Hervy et al. (2015),⁵⁵ the use phase is a major contributor to the life cycle global warming potential (GWP) of automotive composites, as heavier parts increase fuel consumption and emissions. Nanocellulose-reinforced polymers offer high strength and stiffness, enabling lighter structures and reduced fuel use. While their manufacturing phase shows higher GWP and abiotic depletion (ADf) compared to neat polylactide [PLA] and glass fibre-reinforced polypropylene [GF/PP], cradle-to-grave analysis reveals that nanocellulose composites have comparable environmental impacts due to advantages during the use and end-of-life phases (Fig. 4).

Fig. 3 Schematic diagram showing the system boundaries of the model representing the life cycle of BC [bacterial cellulose] – and NFC [nanofibrillated cellulose]-reinforced polymer composites (left), and PLA [polylactide] and GF/PP [glass fibre-reinforced polypropylene] composite (right). The red, blue, and green arrows represent consumables or raw materials required, energy input and waste (materials and energy), respectively. Reprinted from ref. 55 with permission from Elsevier Ltd, copyright 2015.

Fig. 4 [A] Global warming potential and fossil energy consumption for the production, [B] GWP and ADf (from cradle-to-grave) of our two benchmark materials and two nanocellulose-reinforced composites⁵⁵ real-world cases demonstrating LCA-driven design decisions. Reprinted from ref. 55 with permission from Elsevier Ltd, copyright 2015.

Life cycle assessment (LCA) has increasingly been integrated as a critical tool in guiding sustainable material and molecular design decisions. Several real-world case studies across sectors illustrate how LCA can reveal non-intuitive trade-offs, inform early-stage decisions, and enable quantifiable environmental benefits.

In the automotive sector, Saur et al. (2000)⁵⁶ evaluated five alternative materials for vehicle fenders using LCA and found that a polymer blend—polypropylene/ethylene propylene diene monomer (PP/EPDM)—significantly outperformed traditional materials such as steel and aluminum in terms of energy consumption, global warming potential, and part cost, leading to a sustainable material substitution. Similarly, Ribeiro et al. (2008)⁵⁷ demonstrated how LCA, combined with life cycle cost analysis, enabled a comparative assessment of mild steel, ultra-high-strength steel, and aluminum alloys, revealing trade-offs that would not be evident using performance metrics alone.

In the electronics domain, Hossain et al. (2014)⁵⁸ applied an automated, data-mining-based LCA framework (AutoLCA) to redesign components in printed circuit boards and desktop printers. The hotspot analysis led to targeted material and structural redesigns that achieved carbon footprint reductions ranging from 1% to 36%, highlighting the potential of automated tools for rapid, sustainability-oriented iteration. In another study, Mosovsky et al. (2001)⁵⁹ employed the EcoPro LCA tool to compare aluminum and plastic materials for circuit pack faceplates. The analysis revealed that switching to plastic resulted in a fivefold increase in resource productivity and fourfold cost reduction, underscoring LCA's role in identifying both environmental and economic opportunities.

In the construction sector, Namaki et al. (2024)⁶⁰ demonstrated the utility of a building information modeling (BIM)-integrated LCA and multi-criteria decision-making (MCDM) framework for structural material selection. Their analysis showed that recycled steel performed on par with timber in terms of overall sustainability metrics, supporting a shift away from conventional steel in single-family housing projects.

4 Role of innovation management in circular economy integration

4.1 Strategic innovation in nanotechnology development

Strategic innovation plays a pivotal role in advancing nanotechnology development, particularly through robust R&D strategies and cross-sector collaboration. These elements are crucial for integrating nanotechnology into circular economy practices, which aim to minimize waste and maximize resource efficiency. This section explores how strategic innovation drives nanotechnology development and its alignment with circular economy principles.

Research and development (R&D) strategies are the backbone of nanotechnology innovation. These strategies involve systematic approaches to developing new materials, processes, and applications. For instance, the development of nanocellulose as a sustainable packaging material exemplifies how R&D strategies can lead to eco-friendly solutions.⁶¹ Similarly, the integration of green chemistry principles in nanomaterial synthesis highlights the importance of sustainable R&D practices.³⁶

Green chemistry principles emphasize the use of renewable resources, reduction of hazardous substances, and minimization of waste. These principles are increasingly applied in nanotechnology through energy-efficient methods and circular economy strategies to develop environmentally responsible nanomaterials.⁶² For example, the use of nanocellulose, derived from renewable resources, offers a biodegradable and recyclable alternative to synthetic plastics.⁶¹ This approach not only aligns with circular economy principles but also addresses the environmental concerns associated with traditional nanomaterials.

Open innovation strategies, which involve collaboration between academia, industry, and government, are essential for advancing nanotechnology R&D. By leveraging external ideas and technologies, organizations can accelerate the development of innovative nanomaterials and applications. For instance, the adoption of open innovation strategies has been shown to enhance the implementation of circular economy practices by facilitating the sharing of knowledge and resources.⁶³

Cross-sector collaboration is critical for overcoming the challenges associated with nanotechnology development. This involves partnerships between different industries, research institutions, and policymakers to create a conducive environment for innovation. The “Nanotechnology Innovation Diamond” model, which emphasizes the importance of multidisciplinary project teams and a conducive innovation environment, provides a framework for successful nanotechnology R&D.⁶⁴

The nanotechnology innovation diamond identifies six key factors essential for successful innovation in nanotechnology. These include understanding consumer needs and acceptance, integrating nanotechnology with existing industries (hybridisation), promoting interdisciplinary collaboration, benefiting from agglomeration and clustering, developing strong R&D and commercialization skills, and operating within a supportive innovation environment involving academia, industry, and government. Together, these factors help guide effective nanotechnology research, development, and market success.⁶⁴

Multidisciplinary project teams bring together experts from various fields, including materials science, chemistry, biology, and engineering. This diversity of expertise enables the development of innovative solutions that address complex challenges in nanotechnology. For example, the integration of nanotechnology with green hydrogen production highlights the potential of multidisciplinary collaboration in advancing sustainable energy solutions.⁶⁵

The clustering of nanotechnology research projects and initiatives can foster innovation by creating hubs of expertise and resources. This agglomeration effect enables the sharing of knowledge, equipment, and best practices, leading to more efficient and effective R&D processes. The success of such clusters is evident in the development of sustainable nanomaterials for applications in renewable energy and environmental remediation.⁶⁴

The integration of nanotechnology into circular economy practices is essential for achieving sustainable development. Circular economy models aim to reduce waste, optimize resource utilization, and promote the recycling and reuse of materials. Nanotechnology can play a key role in this transition by providing innovative solutions for sustainable production and lifecycle management.

Nanotechnology offers several opportunities for improving the sustainability of production processes. For example, the use of nanocatalysts can enhance the efficiency of chemical reactions, reducing the consumption of raw materials and energy.⁶⁶ Additionally, the development of nanocomposites with improved mechanical and thermal properties can lead to the creation of lightweight and durable materials, reducing the need for frequent replacements and repairs.⁶¹

Effective lifecycle management is critical for ensuring that nanotechnology products are designed for longevity, recyclability, and biodegradability. This involves adopting a cradle-to-cradle approach, where materials are continuously cycled back into production, minimizing waste and the environmental impact of resource extraction.⁶⁷ The integration of nanotechnology with digital tools, such as blockchain and Internet of Things (IoT), can further enhance lifecycle management by providing real-time monitoring and tracking of materials throughout their lifecycle.⁶⁸

4.2 Business models for circular nanotechnology

The product as a service (PaaS) model involves providing customers with access to products through leasing or pay-per-use arrangements, rather than outright ownership. This model encourages companies to design products for durability and recyclability, as they retain ownership and responsibility for the products throughout their lifecycle. In the context of nanotechnology, PaaS can promote the development of sustainable nanomaterials and products that align with circular economy principles.⁶⁹

Remanufacturing and recycling are key components of circular economy business models. These practices involve the recovery of materials from end-of-life products and their reuse in the production of new goods. Nanotechnology can enhance these processes by developing advanced recycling technologies that can efficiently recover and process nanomaterials.⁶⁶ For example, the use of nanotechnology in the recycling of rare earth metals can help reduce the environmental impact of mining and improve resource efficiency.⁷⁰

Circular supply chains aim to minimize waste and optimize resource utilization by promoting the recycling and reuse of materials. Nanotechnology can play a crucial role in enhancing the sustainability of supply chains by developing innovative materials and processes that reduce environmental impact. For instance, the use of nanocellulose in packaging materials can reduce the reliance on synthetic plastics and promote biodegradability.⁶¹

The reviewed studies highlight several approaches to material flow management in circular supply chains. One key method is the development of closed-loop systems, as emphasized by Azka et al. (2024),⁷¹ who focused on reusing goods, components, and materials in nanocellulose composite production. Another approach is waste-to-resource conversion, where Brar et al. (2022)⁷² explored using diverse waste streams for nanoparticle synthesis, and Tsolakis et al. (2021)⁷⁷ investigated algae biomass for producing multiple outputs. Recycling and reworking were central in the model by Omair et al. (2022),⁷³ which incorporated such processes into automobile manufacturing to handle imperfections and minimize waste. Moreover, design for circularity was stressed by Radavičius et al. (2021)⁷⁴ and Tardy et al. (2023),⁷⁵ who highlighted the need for circularity-focused product design. Finally, multi-scale approaches like that of Hasan et al. (2015)⁷⁶ address material flows from the process level to the broader supply chain. Together, these strategies underline the importance of managing the full product lifecycle for effective circular supply chain performance.

Collaboration among various stakeholders plays a crucial role in the successful implementation of circular supply chain models. Industry-academia partnerships, highlighted by Radavičius et al. (2021)⁷⁴ and Tsolakis et al. (2021),⁷⁷ support innovation and knowledge exchange for circular economy solutions. Cross-sector collaboration, as discussed by Sandvik and Stubbs (2019),⁷⁸ is vital in industries like fashion, where textile-to-textile recycling faces significant barriers. Supply chain integration was also emphasized by Hasan et al. (2015)⁷⁶ and Rentizelas et al. (2021),⁷⁹ showing how coordinated efforts across supply chain stages can enhance resource recovery and minimize waste. In addition, technology transfer was identified by Brar et al. (2022)⁷² and Tardy et al. (2023)⁷⁵ as a key benefit of collaboration, enabling the spread of green technologies and circular principles across industries. These frameworks reflect the complex, multi-stakeholder nature of circular supply chains, where coordinated action among manufacturers, suppliers, consumers, policymakers, and researchers is essential for sustainable progress.

4.3 Addressing ethical and societal concerns

The environmental impact of nanotechnology is a significant concern, particularly with regard to the potential toxicity of nanomaterials and their disposal. While nanotechnology offers many benefits, such as improved efficiency and reduced resource consumption, it also poses risks to human health and the environment if not managed properly. For example, the release of nanoparticles into the environment can have unintended consequences, such as bioaccumulation in ecosystems and potential toxicity to aquatic organisms.⁸⁰

Public acceptance of nanotechnology is influenced by perceptions of its benefits and risks. While nanotechnology has the potential to address global challenges such as climate change and resource scarcity, concerns about its safety and ethical implications can hinder its adoption. Addressing these concerns requires transparent communication and public engagement, as well as the development of ethical frameworks that guide the responsible development and use of nanotechnology.⁸¹

The ethical considerations surrounding nanotechnology include issues related to equity, privacy, and governance. For example, the benefits of nanotechnology may not be evenly distributed, leading to disparities in access to innovative solutions. Additionally, the intersection of nanotechnology with advanced computing and artificial intelligence raises concerns about data privacy and surveillance.⁸⁰ Addressing these ethical challenges requires a multidisciplinary approach that integrates robust ethical frameworks and responsible research practices.⁸⁰

5 Keyword co-occurrence analysis of nanotechnology, life cycle analysis, and circular economy

Keyword co-occurrence analysis has been conducted using the PRISMA methodology which provides a systematic way to conduct a review related to specific keywords.⁷⁶ Based on the search conducted in Scopus and Web of Science databases using the keywords “Nanotechnology”, “Life Cycle Analysis” and “Circular Economy” and a limited number of published articles were found related to these keywords. Two clusters of keywords were identified synthesizing two novel themes as follows.

Cluster 1 – Theme: “nanotechnology for environmental remediation”

Keywords: Nanomaterials, Nanotechnology, Contaminants, Wastewater Treatment

This cluster centers around the use of nanomaterials and nanotechnology in addressing environmental contaminants, particularly in the context of wastewater treatment. The presence of terms like contaminants and wastewater treatment highlights the cluster's focus on applying advanced materials to solve pressing ecological issues, especially water pollution. It reflects a research theme focused on innovative technological solutions for environmental sustainability.^82,83

Cluster 2 – Theme: “sustainable design and circular economy strategies”

Keywords: Circular Economy, Eco-innovation, Ecodesign, Ecodesign Tools

This cluster revolves around the principles and tools supporting a circular economy, emphasizing eco-innovation and ecodesign practices. The inclusion of ecodesign tools and eco-innovation suggests a strong interest in developing methodologies and strategies that minimize waste, extend product life cycles, and promote sustainable product development. This theme is rooted in policy, design thinking, and systems innovation aimed at sustainability.^84,85

The density visualization map in Fig. 5 from VOSviewer reveals two high-impact research clusters.^86–88 On the left, the circular economy forms a core topic, surrounded by related themes such as eco-innovation and ecodesign, indicating a strong focus on sustainable design practices. On the right, nanomaterials emerge as a dominant keyword, closely associated with nanotechnology and environmental applications such as wastewater treatment and contaminant removal. The intensity of yellow in both clusters highlights the centrality of these keywords in the current literature. The spatial separation of these clusters suggests that, while both are well-developed areas, there remains limited integration between circular economy principles and nanotechnology applications—highlighting a potential area for interdisciplinary research growth.

Fig. 5 Density visualization map [created by the authors].

The VOSviewer network visualization map presents in Fig. 6, a clear depiction of keyword co-occurrence within the research domain, highlighting two distinct thematic clusters. On the left, the green cluster centers around the concept of the circular economy, closely associated with terms such as eco-innovation, ecodesign, and ecodesign tools. This cluster reflects a research focus on sustainable design practices and innovation strategies aimed at promoting circular economic models. On the right, the red cluster revolves around nanomaterials and includes related keywords such as nanotechnology, contaminants, and wastewater treatment. This indicates a strong research emphasis on the application of advanced materials, particularly nanomaterials, in environmental remediation and water purification processes. Notably, there is a visible link between the two clusters, suggesting an emerging interdisciplinary intersection where sustainable design principles are being integrated with nanotechnology solutions. The size of the nodes and the thickness of the connecting lines provide insights into the prominence and strength of relationships among the keywords, respectively. Notably, the keyword “life cycle analysis” does not appear in the network visualization map, which indicates that future research may be conducted using this keyword and the combination of keywords used to perform the analysis.

Fig. 6 Network visualization [created by the authors].

6 Limitations and future directions

One of the primary limitations of LCA for nanotechnology-enhanced soft materials is the scarcity of nano-specific data. Engineered nanomaterials (ENMs) have unique properties that differentiate them from conventional materials, but there is a lack of comprehensive datasets to inform life cycle inventories (LCIs) and life cycle impact assessments.⁸⁹ For example, there is limited information on the release of ENMs during the use and end-of-life stages, such as weathering, degradation, or recycling processes.⁴⁴ The fate, exposure, and effects of ENMs in the environment and human health are not well understood, making it difficult to develop accurate characterization factors for LCIA.²⁹ While recyclability is a significant end-of-life fate for nanoproducts, there is little research on the environmental and health implications of recycling ENMs.^8,44 These data gaps hinder the ability of LCA to provide a holistic assessment of nanotechnology-enhanced soft materials.

The LCIA phase of LCA faces several methodological challenges when applied to nanomaterials. Current LCIA models do not include characterization factors for ENMs, which are necessary to quantify their environmental and human health impacts.²⁹ Existing models often rely on steady-state assumptions, which do not account for the dynamic behavior of ENMs in the environment. For example, smaller emissions of ENMs can lead to greater fractional deposition in the human lung, highlighting the need for more sophisticated models.²⁹ The embryonic nature of nanomaterial life cycles introduces significant uncertainties, as future applications, production processes, and policy frameworks are not yet well defined. These challenges limit the accuracy and relevance of LCIA for nanotechnology-enhanced soft materials.

Most LCA studies for nanomaterials focus on the production stage, neglecting the use and end-of-life stages. This is particularly problematic for nanotechnology-enhanced soft materials, where the use stage may involve direct environmental releases (e.g., through weathering or degradation).⁴⁴ Additionally, the environmental and health impacts of nanoproducts at the end-of-life stage, such as landfilling, incineration, or recycling, are not well understood.^8,44

To overcome the current limitations in LCA of nanotechnology-enhanced soft materials and better integrate circular economy principles, several methodological improvements have been proposed. Firstly, the development of nano-specific databases is essential, as accurate LCA relies heavily on comprehensive data regarding engineered nanomaterial (ENM) release, fate, and toxicity.⁹⁰ Standardizing the methods used to measure and report ENM emissions, particularly during use and end-of-life stages, will also enhance the consistency and comparability of LCA studies.⁴⁴ Secondly, improvements in life cycle impact assessment (LCIA) models—such as incorporating dynamic fate and exposure modeling, and developing nano-specific characterization factors—will allow for more precise evaluations of environmental and human health risks.²⁹

Moreover, integrating circular economy (CE) principles into LCA frameworks is critical. This includes expanding end-of-life assessments to capture recycling, reuse, and material recovery processes, which are often neglected in conventional LCA.^8,44 A systemic approach that considers material circularity, supply chain interactions, and socio-economic implications can provide a more holistic perspective.^91,92 In addition, the application of prospective LCA and scenario analysis enables future-oriented assessments that anticipate environmental impacts under different production and policy scenarios.⁹³ Engaging stakeholders, including industry and policymakers, further enhances the relevance and applicability of LCA findings.

Finally, focusing on sustainable production and material design can greatly reduce environmental burdens. Emphasizing green chemistry approaches and selecting abundant, biodegradable, or bio-based materials aligns both LCA and nanotechnology development with CE principles.^94,95 Collectively, these advancements will help bridge the methodological gaps in LCA and support the responsible innovation of nanotechnology-enhanced soft materials.

7 Conclusion

Nanotechnology-enhanced soft materials present both opportunities and challenges for sustainable development. While their superior performance properties align with circular economy goals, their lifecycle impacts—particularly during production and end-of-life—can be significant. Life cycle assessment (LCA) offers a critical tool for evaluating these impacts, but current methodologies lack nano-specific data and models. Advancing sustainable nanomaterials requires not only greener synthesis and improved design strategies but also interdisciplinary collaboration and innovation management. Integrating circular economy principles into nanotechnology development is essential for realizing their full environmental and societal benefits.

Data availability

All the data included in this manuscript.

Author contributions

Sanduni Dabare: writing – original draft, data curation, visualization. Sisitha Rajapaksha: writing – review & editing, PRISMA analysis, VOSviewer maps generation. Imalka Munaweera: writing – review & editing, supervision, conceptualization. All authors have approved the final version of the manuscript.

Conflicts of interest

The authors declare that there is no conflict of interest.

Acknowledgements

Financial support for this study is acknowledged by the University of Sri Jayewardenepura, Sri Lanka under the research grant number RC/URG/SCI/2024/12.

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