Mono-material product design with bio-based, circular, and biodegradable polymers

The traditional multi-material product design of plastic products significantly complicates both existing and emerging recycling processes. Here, we discuss the concept mono-material design, which is based on circular biodegradable polymers made a single monomer, delivering tailorable properties via molecular or macromolecular engineering without changing its chemical makeup composition. Everyday such as those designed for packaging, while seemingly simple, are highly engineered, multi-component materials. Namely, when material requires specific that cannot be achieved by polymer, common strategy to use different same polymer modified copolymerization functionalization and/or add other additives bring about desired properties. While this approach delivers lifetime performance, it also substantially recycling. Using packaging an example, keep food fresh, protect products, brand goods, combination 3 12 usually required form multi-layered products.1Butler T.I. Morris B.A. Multilayer Flexible Packaging. Elsevier, 2016Google Scholar For condiment sachet packet, could comprise low-density polyethylene (LDPE) inner layer sealability, functional oxygen barrier poly(ethylene-co-vinyl alcohol) (EVOH), acetate) adhesive tie layer, outer strength high-density (HDPE) poly(ethylene terephthalate) (PET), all assembled through coextrusion lamination.2Anukiruthika T. Sethupathy P. Wilson A. Kashampur K. Moses J.A. Anandharamakrishnan C. Packaging: Advances in Preparation Techniques Emerging Food Applications.Compr. Rev. Sci. Saf. 2020; 19: 1156-1186Crossref PubMed Scopus (94) Google these types materials clearly useful, conventional mechanical represents major technical challenge because typically create heterogeneous immiscible blends. there potential ways compatibilize blends, using dynamically crosslinked block copolymers unify phases3Clarke R.W. Sandmeier Franklin K.A. Reich D. Zhang X. Vengallur N. Patra T.K. Tannenbaum R.J. Adhikari S. Kumar S.K. et al.Dynamic crosslinking compatibilizes mixed plastics.Nature. 2023; 616: 731-739Crossref (1) separate layers selective solvents recycle them individually,4Walker T.W. Frelka Shen Z. Chew A.K. Banick J. Grey Kim M.S. Dumesic Van Lehn R.C. Huber G.W. Recycling multilayer solvent-targeted recovery precipitation.Sci. Adv. 6eaba7599Crossref (105) technologies remain nascent challenged diversity used today.5Horodytska O. Valdés F.J. Fullana Plastic Films Waste Management – A State Art Review.Waste Manag. 2018; 77: 413-425Crossref (226) As alternative approach, herein propose creation multi-functional can potentially realized single, compatible Future sustainable would ideally derived from (2) biologically monomer6Cywar R.M. Rorrer N.A. Hoyt C.B. Beckham G.T. Chen E.Y.-X. Bio-Based Polymers with Performance-Advantaged Properties.Nat. Mater. 2021; 7: 83-103Crossref (108) (3) chemically closed-loop end-of-life7Shi Reilly L.T. Phani V.S. Coile M.W. Nicholson S.R. Broadbelt L.J. Design Principles Intrinsically Circular Tunable Properties.Chem. 2896-2912Abstract Full Text PDF (0) Scholar,8Coates Getzler Y.D.Y.L. Chemical Monomer Ideal, Polymer Economy.Nat. 5: 501-516Crossref (424) Scholar,9Hong M. Chemically recyclable polymers: economy sustainability.Green Chem. 2017; 3692-3706Crossref (4) biodegradable.10Westlie A.H. Quinn E.C. Parker C.R. Synthetic Biodegradable Polyhydroxyalkanoates (PHAs): Recent Challenges.Prog. Polym. 2022; 134101608Crossref (8) First, here mean broad range readily accessible monomeric building (see Box 1). Second, bio-based monomer greatly reduces synthetic complexity materials, increases circularity (i.e., waste) enabling more facile recycling, includes biogenic carbon reduce environmental impact synthesis.11Zheng Suh Strategies Reduce Global Carbon Footprint Plastics.Nat. Clim. Chang. 2019; 9: 374-378Crossref (458) Third, will have capacity depolymerize completely back makes creates end-of-life not available today. Finally, takes “Recycle First” if leakage into natural environment occurs should able biodegrade, thus reducing pollution. key how make one behave like many properties) overall makeup, either polymer’s stereomicrostructures architectures monomer’s structures functions so polymerized differently (by mechanisms) multiple properties, namely single-monomer-sourced polymers. In commentary, describe three approaches meet challenge: hybrid monomers 1) selectively produce exhibit various components but recycled closed loop; stereomicrostructure engineering, tuning stereo-configuration backbone turn retaining transform single-monomer-based polyester much types; topological/architectural tune following highlighted examples above show possible span strong rigid thermoplastics, flexible plastics, stretchable elastomers, tough thermoplastic crystalline fibers, even adhesives. Within framework, challenging optimize, concurrently, contrasting polymerizability/depolymerizability recyclability/performance To address challenge, recently developed design12Shi Hybrid Synergizing Property Trade-offs Developing Circularity Performance.Angew. Int. Ed. (e202301850)Google hybridizes parent pairs contrasting, mismatching, matching offspring only above-described conflicting radically alter resultant far beyond limits what homopolymers their normally achieve. particular, olefin/lactone bifunctional γ-butyrolactone (γ-BL), low-ceiling-temperature (LCT) toward ring-opening polymerization (ROP) polyester, cyclohexene, LCT metathesis (ROMP) afford poly(cyclic olefin), achieves unique orthogonal (de)polymerization establish “one monomer–two polymers–one monomer” framework (Figure 1A).13Shi Clarke McGraw M.L. Closing “One Monomer-Two Polymers-One Monomer” Loop Orthogonal (De)Polymerization Lactone/Olefin Hybrid.J. Am. Soc. 144: 2264-2275Crossref (26) resulting polyolefin catalyzed ROMP ROP process, respectively, distinctively thermal applied application needs. More significantly, combining two classes covalently polyolefin-polyester copolymer physical mixture still yields fully system easily broken down closing (CRM) loop homopolymers, copolymers, mixture. This resembles another α-methylene-γ-butyrolactone (MBL), naturally occurring biomass-sourced containing reactive exocyclic C=C bond stable five-membered γ-BL 1B). Regulated simply temperature, MBL undergo poly(2-methylene-4-hydroxybutyrate) (P4HB=) kinetically favored pathway acrylic PMBL thermodynamically vinyl-addition (VAP) pathway.14Tang Hong Falivene L. Caporaso Cavallo Quest Converting Biorenewable Bifunctional α-Methylene-γ-Butyrolactone Degradable Recyclable Polyester: Controlling Vinyl-Addition/Ring-Opening/Cross-Linking Pathways.J. 2016; 138: 14326-14337Crossref (109) Both CRM markedly performance offering example monomer–multiple loop. (P4HB=)14Tang PMBL15Gilsdorf R.A. Nicki M.A. High Recyclability Vinyl Lactone Acrylic Bioplastics.Polym. 11: 4942-4950Crossref been shown circularity. Worth noting P4HB= vinyl-functionalized P4HB (the pendent vinyl group provides access property modifications P4HB), exhibits high glass-transition temperature (Tg) 195°C, ∼90°C higher than petroleum-based poly(methyl methacrylate) (PMMA) solvent resistant PMMA well. Overall, orthogonality processes has achieved, (PHAs) class polyesters bioderivable Poly(3-hydroxybutyrate) (P3HB) most PHA subject academic commercial attention since mid-21st century. lies methyl group, found PHAs absolute (R)-configuration, making perfectly isotactic (it). configuration sequence configurations space, stereomicrostructure, engineered deliver strength, rigidity, flexibility, maintaining bio-based, eight-membered dimethyl diolide (8DLMe) platform, provide it-P3HB16Tang Synthesis Perfectly Isotactic Melting Bacterial Poly(3-Hydroxybutyrate) Bio-Sourced Racemic Cyclic Diolide.Nat. Commun. 2345Crossref (85) (which barriers water vapor oxygen, essential design),17Sangroniz Zhu J.-B. Tang Etxeberria Sardon H. Packaging Materials Desired Mechanical Barrier Properties Recyclability.Nat. 10: 3559Crossref (175) stereosequenced P3HB ductile tough),18Tang Westlie Watson E.M. Stereosequenced Crystalline Diastereomeric Mixtures.Science. 366: 754-758Crossref (86) optically clear syndio-rich (sr) P3HB.19Quinn Sangroniz Caputo M.R. Xu Urgun-Demirtas Müller A.J. Installing Controlled Stereo-Defects Yields Semicrystalline Toughness Optical Clarity.J. 145: 5795-5802Crossref All 8DLMe, synthesized simple modulations choice diastereomers catalysts 2). Traditionally, case ß-butyrolactone, simplest lactone P3HB, stereocenter leading limited stereomicrostructures. our recent work sr-P3HB,19Quinn showed introducing controlled stereoerrors along chain accounts drastic changes thermoplastic, st-P3HB, sr-P3HB. Our ongoing shows principle learned diverse portfolio include elastomers Hence, microstructural allow us essentially necessary mimic (e.g., packaging) where composition backbone, thereby simplifying One attractive features biodegradability ambient, unmanaged environments (in soil bio- it-P3HB 105–145 days reach 90% degradation19Quinn Scholar). redesigning stance, designing important, waste leaked cause adverse health effects. We envision first biodegraded “emergency” environment) creating “back-up plan” biodegradation. sr-P3HB reported demonstrated melt-processability mechanically recyclable)19Quinn fresh soil. Further now within sight waste. advanced P3HB-based include: properties; microstructure engineering; equivalent products. It well known architecture linear vs. branched crosslinked) topology cyclic), see 1, renders drastically regulating utilized further modulate exemplified here, especially widen space circular, monomer. star-shaped was possess lower shear viscosity counterparts.20Ebrahimi Hatzikiriakos S.G. Mehrkhodavandi Rheological Characterization Star-Shaped Linear Poly(Hydroxybutyrate).Macromolecules. 2015; 48: 6672-6681Crossref (18) Combining topological architectural stereomicrostructural described wider furthering P3HB. alternative, employs designer produces single-monomer suite types, blocks. Many future opportunities remain, including: economically competitive synthesis at-scale abundantly feedstocks; establishment CRM, PHAs; “drop-in” lamination processing solutions monomers; complete techno-economic analyses life cycle assessments novel replacements.7Shi ultimately met coupling bio/chemocatalytic energy efficient recovering highlights need close PHAs. likely fossil carbon-based they may plastics exhibit, rendering at least partially incompatible manufacturing additional, important means tailor plastics. realize commercialization processes, community needs infrastructure methods sure successfully processed functionable strategies working together industrial communities, bio-sourced, recyclable, alternatives today’s multi-material-based Funding provided U.S. Department Energy, Office Energy Efficiency Renewable Advanced Manufacturing Technologies (AMMTO), Bioenergy (BETO). performed part Bio-Optimized Thermoplastics out Landfills Environment (BOTTLE) Consortium supported AMMTO BETO under contract DE-AC36-08GO28308 National Laboratory (NREL), operated Alliance Sustainable LLC. BOTTLE members Colorado University. authors declare no competing interests.Box 1GlossaryMonomer: Monomers blocks Typically, functionality, double heterocyclic ring, transformed reaction link molecules together, becoming repeating unit. combine favorable depolymerization possessed complementary functionalities brought subunits hybridized structure synergize overcome performance/recyclability trade-offs.Polymer: macromolecule composed bonded units long chain. called whereas combined characteristic in-between homopolymers. Synthetic, classified five including coatings, interchangeably, represent (major) type polymer.Polymer topology: refers connected one, two, dimensions, corresponding linear, branched, (network) structures. sequences, formation random, block, alternating, graft copolymers. three-dimensional shapes relationships individual chains arranged whole polymer. Common topologies rings, stars, dendrimers, combs, ladders, rotaxanes, catenanes. Changes lead sharply properties.Sustainability design: When sustainability, several factors considered entire material. Complete (LCAs) conducted early often compared conventional, ensure benefit any new introduced market. “Sustainability” recyclability biodegradability, LCA metrics water/energy consumption greenhouse gas (GHG) emissions raw extraction → disposal recycling) essential. Monomer: trade-offs. Polymer: Sustainability