Polymers are ubiquitous in the modern world, and the demand for and production of plastics products continues to climb. Historically, the chemical manufacturing of plastics has focused on key features, such as durability, low-cost, and multifunctionality; however, these aspects also challenge current interventions to combat the plastics waste dilemma. I will overview plastics sustainability from the perspective of transitioning from a linear to a circular economy, addressing macromolecular diversity and plastic waste complexity, reducing dependence on petroleum feedstocks, and maintaining (or improving) material performance.

Polyurethane (PU) is a major class of polymers invented over 80 years ago. Due to the unique reactivity of isocyanates and the wide variety of available building blocks, PU materials cover a broad spectrum of properties expected for polymeric materials. PU foams represent the largest share of PU production, offering excellent mechanical properties relative to weight, as well as sound and thermal insulation, shock absorption, and the ability to fill complex molds. However, the inherent toxicity of isocyanates and the lack of efficient recycling methods have driven the search for greener and more modern approaches to PU and PU foam production. Recently, we demonstrated that five-membered cyclic carbonates (5CC) are a promising alternative to eliminate isocyanates, forming polyhydroxyurethane (PHU) when reacting with amines. Additionally, when water and a catalyst are added, 5CC-based systems can self-blow, leading to foam. 5CC can be easily synthesized via CO₂ coupling with epoxides, making production cost-effective using widely available chemicals and waste streams. Their lower reactivity also reduces toxicity. Despite these advantages, achieving PU-like foaming conditions (room temperature, a few minutes) remains challenging. We have developed a cascade exotherm strategy to meet these requirements while maintaining a process compatible with existing PU production lines. This presentation will explore the chemical mechanisms underlying the foaming process and provide an evaluation of the thermo-mechanical properties of the resulting PHU foams.

The development of sulfur-decorated polymers¹, particularly dithiolane-functionalized derivatives, offers a promising approach for delivering responsive and dynamic networks in advanced circular material design. Building upon this premise, a liquid polybutadiene (PBD), a widely available commercial polymer, is functionalized through a metal- and catalyst-free electrophilic multicomponent post-polymerization modification (MC-PPM) process valorizing renewable and commodity feedstocks (Figure 1).² Specifically, 2-methyltetrahydrofuran (MTHF), derived from agricultural by-products, and biomass-based lipoic acid are employed to introduce 1,2-dithiolane groups into the commercially available polymeric structure (i.e., PBD).³ Consequently, the functionalization facilitates the formation of dynamic, reversible crosslinks via thiol-disulfide interchange reactions, imparting enhanced self-healing properties and enabling chemical recycling within closed-loop processes.⁴
The resulting sulfur-decorated PBD networks exhibit tunable crosslink density, excellent thermomechanical stability, and novel unconventional luminescent properties, making them sustainable alternatives to conventional materials like vulcanized rubber. In summary, the current work presents an innovative strategy for the development of recyclable, high-performance polymer systems derived from renewable and commodity feedstocks.

Poly(vinyl chloride) (PVC) is one of the most consumed polymers worldwide (more than 50 million tons per year) and is used to manufacture many items, such as packing, construction, and healthcare devices. Despite all the criticism, global PVC consumption has increased at a steady rate of 5% per year. Currently, PVC is produced on an industrial scale only via free radical polymerization (FRP). However, several inherent limitations of FRP have stimulated interest in the synthesis of new PVC materials by reversible deactivation radical polymerization (RDRP) methods [1]. Despite the many successes achieved, RDRP of nonactivated monomers, such as vinyl chloride (VC), presents several challenges to the scientific community. Several properties of VC make its control by RDRP techniques particularly challenging. At the present time, single electron transfer degenerative chain transfer living radical polymerization (SET-DTLRP) [2], cobalt-mediated radical polymerization (CMRP), activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP), supplemental activator and reducing agent (SARA) ATRP, electrochemically mediated ATRP (eATRP), reversible addition-fragmentation chain transfer polymerization (RAFT) [3], nitroxide-mediated polymerization (NMP) [4] and macromolecular design via the interchange of xanthate polymerization (MADIX) [5] are the available RDRP methods for VC (co)polymerization. New polymerization systems, novel PVC-based materials, and the latest developments in the RDRP of VC will be critically discussed.

Polyolefins are characterised by their high chemical resistance and nonpolarity.¹ As a result, these materials currently pose environmental challenges, are not compatible with other polymers and cover a limited part of property space.² To address this, innovative chemical recycling and upcycling methods are required. Post-polymerisation modification (PPM) has emerged as a powerful and versatile late-stage strategy for filling the gap in polyolefin chemical space and extending property space. PPM enables fine tuning of the polymeric (physico)chemical properties, introduces possibilities for recyclability and allows for the synthesis of new valuable and versatile products that are challenging to access through bottom-up approaches. While many PPM synthesis strategies are currently being explored, examples of metal-free approaches to selectively install polar groups on the polymer backbone are still scarce.³

Here, we report on metal-free PPM approaches that efficiently installs oxygen and nitrogen containing polar groups onto different types of polyolefin backbones. Photochemical oximation of PE using organic-based radical chemistry as well as thermally induced nitration of polybutadiene will be discussed. In-depth characterisation of the modified polymers sheds-light on the regioselectivity, the random distribution of the groups and showed that we can tailor the polymeric properties by installing various levels of functional groups up to as high as 2.9% for the photochemical approach and as high as ~18% using the thermochemical approach.⁴ We also show that the functionalisation degree and selectivity are tuneable, notable without radical-induced backbone cleavage nor losing the key thermal and mechanical properties of the starting polyolefins (Figure 1).

Within the frame of our current linear economy based on the take-make-use-dispose principle, each year, 1 billion tires are discarded¹. Thus, the upcycling of polybutadiene (PBD), one of the main constituents in post-consumer tires, is a critical goal for progressing toward a circular plastic economy². Accordingly, this work demonstrates how the toolbox of metal-free, electrophilic multicomponent reactions (MCRs) can be utilized as an efficient strategy for the Post-Polymerization Modification (PPM) of PBD, enabling the incorporation of diverse functionalities, such as bromine moieties, pendant ethers, and esters³. Thus, the stated PPM allows for the preparation of a tailor-made macroinitiator decorated with functional units (e.g. curcumin) to enable the metal-free Atom Transfer Radical Polymerization (ATRP)⁴ towards the synthesis of a plethora of functional brushes e.g., polyethylene glycol (PEG), poly(N-isopropylacrylamide) (PNIPAM), and PNIPAM-poly(oligoethylene glycol acrylate) (PNIPAM-POEGA), which are grafted onto the modified PBD. Hence, compared to pristine PBD, this added structural versatility offers the opportunity to optimize the thermo-mechanical, morphological, and optical properties of the polymers, and enables their potential applications as post-lithium energy storage materials. Ultimately, this platform presents a transformative pathway for repurposing discarded PBD into high-value materials (brushed (co)polymers), with future expansions envisioned for surface modifications of vulcanized rubber, contributing to a circular plastic economy.