Recycling of polyolefins using recycled PVC under sunlight

Domain: physics
Published: 2026-02-02
Editorial outcome: minor_revision

Abstract
The recycling of polyolefin plastics is often hindered by high energy consumption and low economic efficiency. In particular, the recycling of poly(vinyl chloride) is especially challenging. Here, we present a protocol to recycle poly(vinyl chloride) into a photothermal agent for the depolymerization of polyolefins under sunlight. By dechlorinating the poly(vinyl chloride), we harness its unique ability to convert sunlight into the energy required to break C-C bonds in polyolefins. This protocol allows for the transformation of low-density polyethylene, high-density polyethylene, and polypropylene into waxes enriched with terminal olefins. Furthermore, it can also enable the conversion of polystyrene, poly(methyl methacrylate), poly(α-methyl styrene), styrene-acrylonitrile copolymer, and acrylonitrile-butadiene-styrene into their respective monomers. This broad applicability makes our protocol suitable for recycling of a wider range of post-consumer plastics and their mixtures under ambient environment. This work provides an effective strategy for polyolefins recycling using waste plastics and solar energy.

Introduction
Plastic is a highly prevalent material in everyday use due to its low cost, durability, and versatility. Globally, the production of plastic is steadily increasing, with annual output over 360 million tons1,2. Polyolefins, such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), poly(vinyl chloride) (PVC), polypropylene (PP), and polystyrene (PS), constitute over half of the total plastic production3. Despite their widespread use, the recycling rate of most polyolefin plastics remains low4. After use, these plastics are predominantly landfilled, incinerated, or mismanaged (Fig. 1a), leading to significant environmental pollution5,6. This is due to the chemical stability of polyolefin plastics, which means that they can take hundreds of years to decompose naturally in the environment7.

An ideal solution to tackling the problem of plastic waste lies in recycling it for circular development. The methods for recycling plastics encompass both mechanical and chemical processes8. However, due to the limitations of sorting technology and the degradation of material properties, mechanical recycling is not an ideal method for recycling large amounts of plastic wastes9,10. Chemical recycling and upcycling approaches, which convert polyolefins into monomers or value-added chemicals for reuse, are envisioned as promising solutions to deal with high volume post-consumer wastes9,11–13. Recently, several chemical methods have been developed for the conversion of polyolefins, such as pyrolysis14–16, catalytic cracking17,18, hydrocracking and hydrogenolysis19–22, olefin metathesis23–25, oxidation26–36, etc. Nevertheless, the high bond dissociation energy (BDE) and low polarity of the chemical bonds in polyolefins (e.g., BDE: ~85 kcal/mol for the C–C bond in PE)37,38 necessitate substantial energy input for their chemical conversion, impeding plastic recycling efforts (Fig. 1b)39. Therefore, the utilization of renewable energy to facilitate the conversion of polyolefins is in urgent demand40. Photochemical conversion, which could harness solar energy directly, provides an alternative solution to plastics recycling by avoiding high consumption of fossil fuels, rendering it an optimal choice for facilitating polyolefin conversion41–46.

Another challenge associated with polyolefin reuse is the recycling of PVC. In the recycling process, it is difficult to avoid mixing PVC with other plastics. However, PVC wastes typically contain a high level of plasticizers, which will affect the recyclability of both PVC itself and the mixed plastics47. Furthermore, PVC is prone to undergoing elimination reactions to generate hydrogen chloride during the recycling process, leading to reactor corrosion and catalyst poisoning8. A promising strategy to address this issue is to utilize the chlorine in PVC for other reaction processes that require chlorine. For instance, recent studies have reported using PVC for the chlorination of arenes48,49 and ketones50. The carbon chain, apart from chlorine, is another valuable component in PVC, but it has not been well utilized after dechlorination (Fig. 1c). We hypothesize that PVC after the removal of hydrogen chloride possesses abundant conjugated bonds, which exhibits photothermal effects through the thermal vibration mechanism and can be potentially applied to transformation of polyolefins.

Here, we have presented an innovative polyolefin recycling method that utilizes waste PVC and solar energy (Fig. 1d)51. This protocol is highly efficient in terms of both time and material usage, capable of converting most of the common conventional plastics covering resin codes 2–7 under ambient pressure and air conditions with sunlight exposure. Using dechlorinated PVC (dPVC) as a reusable photothermal agent, the recycling process of polyolefins was completed within just a few minutes. During this process, HDPE, LDPE, and PP were depolymerized into value-added olefins, while PS, poly(methyl methacrylate) (PMMA), poly(α-methyl styrene) (PAMS), styrene-acrylonitrile copolymer (SAN), and acrylonitrile-butadiene-styrene (ABS) were recycled back into their corresponding monomers. Moreover, this protocol has been successfully applied to the recycling of post-consumer plastic wastes, including single plastics, mixed plastics, and even kilogram-scale plastics. The efficient conversion process utilizing solar energy would facilitate polyolefins recycling and upcycling, reducing white pollution and greenhouse gas emissions.

Results
Polyolefins recycling
Initially, a photothermal agent was obtained from PVC. In order to achieve the comprehensive valorization of PVC, a bromopropane-catalysed chlorine transfer protocol was adopted to enable the efficient reuse of chlorine in PVC50. Chlorinated ketones derived from ketones can be used in the synthesis of the nonsteroidal anti-inflammatory drug naproxen. Another raw material, PVC, upon dechlorination, transformed from its original white solid state into an insoluble black polymer. After washing, drying, and grinding, a black powder of dPVC was obtained with a yield of 72 wt% relative to PVC (Fig. 2a). To investigate the capability of dPVC in utilizing solar energy for the conversion of polyolefins, the chemical conversion of PE and PP was first attempted. According to Liu’s work16, PE and PP can be converted into olefins under heating conditions, which can then be oxidized to synthesize fatty acids for the production of surfactants. Utilizing solar energy as the driving force for this transformation will make the approach more practical. A mixture of polyolefin and dPVC (10 wt% with respect to the polyolefin) was placed in a quartz crucible within a flask (Supplementary Fig. 1). When sunlight (100-110 mW cm-2), focused by a concave mirror (with a diameter of 30 cm), was directed onto the reactants in the crucible, white smoke was immediately generated. This smoke likely consisted of fragments from the broken polyolefin that, after escaping the crucible, condensed onto the colder walls of the flask. With continued irradiation, the polyolefin in the crucible gradually disappeared, and waxes accumulated on the flask wall. The entire process, from the start of irradiation to the completed disappearance of the polyolefin in the crucible (the end of the reaction), took only 2-3 minutes. The isolated yields of waxes generated from LDPE (Mn, 51 KDa), HDPE (Mn, 46 KDa), and PP (Mn, 99 KDa) were 86, 88, and 76 wt%, respectively (Fig. 2b). By installing a balloon on the reaction device, it was observed that only a negligible amount of gaseous products might be generated. This phenomenon was presumably due to the fact that after the polyolefin broke down into waxy products, these products immediately escaped from the crucible, thereby preventing the transformation into products with lower molecular weights.

Nuclear magnetic resonance (NMR) spectroscopy was initially used to characterize these waxy products, revealing that the olefins in the waxes were predominantly terminal olefins, and was consistent with Liu’s work. The 1H NMR also indicated that there were small amount of aldehydes and aromatic hydrocarbons in the products of LDPE and HDPE (Supplementary Figs. 2 and 4). Among them, the aldehydes were likely the result of the reaction between the polyolefins and oxygen, while the aromatic hydrocarbons were the result of cyclization and dehydrogenation. Aldehydes and aromatic hydrocarbons were hardly observed in the products of PP, which might be due to the branched-chain structure of PP. Additionally, gas chromatography–mass spectrometry (GC-MS) showed that the waxes were predominantly composed of olefins, with a small amount of alkanes (Supplementary Figs. 8–13). This is likely because the reaction system provided a sufficiently high temperature, which facilitated the β-scission of the radical intermediates, resulting in the formation of olefins16. Due to the inability of GC-MS to detect low-volatility heavy hydrocarbons, the waxes were further characterized by Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to determine the molecular weight distribution. Based on the spectra, the number-average molecular masses of the waxes from HDPE, LDPE, and PP were 501, 478, and 472, respectively, corresponding to olefins with carbon numbers of 36, 34, and 34 (Supplementary Figs. 15, 17, and 19). It’s worth noting that in the absence of dPVC, neither PP nor PE could generate waxy products after being irradiated under concentrated sunlight for three minutes (Supplementary Table 5).

On the basis of the above results, the process using solar energy was applied to other commercially available and high-volume polyolefin recycling. Homopolymers PS, PAMS, and PMMA, when mixed with dPVC and butylated hydroxytoluene (BHT), decomposed into corresponding monomers and condensed on the flask walls under concentrated sunlight. As analyzed by gas chromatography (GC) with mesitylene as the internal standard, the monomer yields were determined to be 65%, 65% (isolated yield: 65%), and 68%, respectively. However, they were failed to yield monomers without dPVC (Supplementary Table 6). BHT was added to prevent the monomers from repolymerizing. When BHT was absent, the yield of monomer was decreased (Supplementary Table 2, entry 1). The commonly used binary copolymer SAN in daily life also decomposed into styrene and acrylonitrile, with yields of 50% and 26%, respectively. Terpolymer ABS, under the combined action of dPVC and sunlight, could yield 41% styrene and 18% acrylonitrile (Fig. 2c). Given the prevalence of mixed plastic waste in everyday life, achieving degradation of mixed plastics can effectively avoid the difficulties in plastic recycling caused by classification52. To our delight, mixtures of polyolefins with different monomers could also be depolymerized using dPVC as a photothermal agent and sunlight as an energy source. The yields of styrene (59%), α-methyl styrene (65%), and methyl methacrylate (68%) were comparable to those of single polyolefin depolymerization monomers (Fig. 2d). These results indicate that the dPVC can depolymerize various polyolefins without interference, suggesting significant application potential for this protocol in the field of mixed plastic recycling.

Post-consumer plastics recycling
Post-consumer plastics often contain additives such as dyes, antioxidants, and plasticizers, whose presence may hinder the depolymerization process, and therefore poses significant challenges for the recycling and upcycling of polyolefins53. To further explore the potential practical applications, it was attempted for the recovery of post-consumer plastic waste from daily life. The initial attempt involved recycling PVC waste plastics to synthesize photothermal agents, which were then used for the recovery of other polyolefin plastics. PVC gloves (PVC, 57 wt%, Mn, 92 kDa; DOTP, 41 wt%), PVC tubings (PVC, 63 wt%, Mn, 53 kDa; DEHP, 35 wt%), and PVC mats (PVC, 66 wt%, Mn, 57 kDa; DPHP, 34 wt%), after undergoing chloride transfer, all successfully generated photothermal agents. Despite the presence of significant amounts of plasticizers and varying molecular masses of PVC in these plastic products, the resulting agents were all capable of depolymerizing PS under sunlight exposure. Depolymerization experiments under sunlight showed that the yields of styrene were 58%, 56%, and 61%, respectively (Fig. 3a). These results indicate that the synthesis of photothermal agents from PVC waste plastics has good applicability. Subsequently, dPVC synthesized from discarded PVC gloves was used to attempt the recycling of common polyolefin plastic products in daily life (Fig. 3b). Under sunlight irradiation, the HDPE plastic bucket was recycled to yield waxes containing terminal olefins with 83 wt% isolated yield. The LDPE plastic bag and PP food container underwent chemical conversion to produce waxes with isolated yields of 84 wt% and 70 wt%, respectively. A PS cup was subjected to sunlight irradiation to recover 60% styrene. An identical trial with a used plastic sheet made from PMMA provided 80% methyl methacrylate. These results indicate that the method is well-suited for the recycling of real polyolefin plastics in everyday life.

Considering that daily waste recycling usually collects polyolefin mixtures, which are extremely difficult to separate. Finding a generic and profitable method to recycle polyolefin mixtures is thus imperative. To this end, a recycling scheme for mixed plastics is proposed (Fig. 3c). After mixing commercial plastics, including HDPE, LDPE, PP, PVC, PS, and PMMA, a chlorine transfer reaction occurred in a mixed solvent of DMF and DMSO, where the PVC was utilized to produce α-chloroketone and photothermal agent. Methanol was then added to the system to precipitate out the unreacted polyolefins and dPVC. The filtered mixture of dPVC and polyolefins was directly irradiated under concentrated sunlight, ultimately yielding 71 wt% waxes, 42% styrene, and 58% methyl methacrylate. This approach can avoid the difficult sorting tasks in plastic recycling and prevent the generation of large amounts of hydrogen chloride when recycling PVC-containing mixed plastics, promoting the recovery of daily plastics. To further demonstrate the practicality of this reaction, a kilogram-scale polyolefin depolymerization experiment was attempted using a distillation apparatus (Supplementary Fig. 43). By employing batch feeding, the decomposition of one kilogram of PS cups was achieved with only loading 0.1 wt% of dPVC under sunlight, yielding 0.97 kilograms of liquid product (Fig. 3d). The primary component of this liquid product was styrene, accounting for 57 wt% of the mixture, with a recovery rate of 55%. Additionally, the liquid product contained other valuable chemicals such as toluene, ethylbenzene, and α-methyl styrene (Supplementary Fig. 44). The above experimental results fully demonstrate that the protocol for converting polyolefins by dPVC under sunlight has great practicality in the recycling and upcycling of PVC, HDPE, LDPE, PP, PS, and PMMA waste plastics.

Photothermal effect and recycling test of dPVC
In order to evaluate the solar-thermal conversion ability of dPVC, the light absorption ability of dPVC and recycled dPVC (recycled from the depolymerization experiment of PS) were measured with a UV-Vis-NIR spectrophotometer. As shown in Fig. 4a, the black dPVC powder exhibited excellent absorption of sunlight over the whole solar spectrum. In the visible light region (400-700 nm), which accounts for 45% of the total energy of sunlight, the light absorption rate of dPVC exceeded 90%. Even in the short-wavelength near-infrared region (700-1100 nm), dPVC still showed good light absorption, but the absorption rate gradually decreased with increasing wavelength in long-wavelength near-infrared region (1100-2500 nm). After the depolymerization of PS, the recycled dPVC maintained its light absorption capability in the visible light region, and its light absorption capacity in the infrared region significantly increased. This may be due to partial unremoved chlorine undergoing further removal under sunlight, resulting in a higher degree of conjugation by generating more double bonds. This suggest that the dPVC may exhibit improved photothermal conversion ability after use.

Under concentrated sunlight exposure, dPVC absorbed sunlight and converted it into thermal energy, rapidly raising the temperature of the reaction system to 470 °C within 1 minute and maintaining this temperature until the reaction concluded (Fig. 4b). The entire process from initial illumination to reaction completion took approximately 2 minutes. Since the temperature increase was a result of dPVC converting light energy into heat, the high temperature was concentrated only in the crucible where the photothermal agent was present, while on the flask walls, the temperature remained at 75 °C (Fig. 4c). This created a temperature gradient, preventing further reaction of the depolymerization products and enhancing the yield of the products.

Thermogravimetric analysis (TGA) was used to estimate the stability of dPVC. The thermogravimetric curve indicated that weight loss began at 126 °C and reached 42% by 380 °C. As the temperature increased, further weight loss occurred until the weight stabilized at 650 °C. In contrast, the recycled dPVC (recycled from the depolymerization experiment of PS) exhibited significantly enhanced thermal stability, with only 6% weight loss by 330 °C, possibly due to adsorbed water or residual solvent. Even at 680 °C, 76% of the material’s mass was retained. The enhanced thermal stability is presumably ascribed to the removal of residual chlorine in dPVC under solar irradiation. This chlorine elimination was confirmed in subsequent experiments. Both UV-Vis-NIR absorption spectroscopy and TGA indicate that the structure of dPVC had undergone changes after participating in the reaction. An experimental investigation was conducted to explore whether its photothermal conversion has also changed. Experiments demonstrated that, without additional supplementation of dPVC, the photothermal agent consistently achieved the efficient depolymerization of PS over 10 successive reuse cycles (Fig. 4d). The yield of styrene in some experiments fluctuated, possibly due to occasional cloud cover blocking the sun. These results suggest that the dPVC underwent structural changes during its first exposure to sunlight for the depolymerization of polyolefins, increasing its light absorption capacity. However, its ability to depolymerize polyolefins under sunlight had not been lost, and thus it could be reused in the recycling of polyolefins.

Characterization of dPVC
Scanning electron microscopy (SEM) images (Fig. 5a–b) presented the microscopic morphological features of dPVC. It can be seen from Fig. 5a that the dPVC powder were predominantly in the form of irregular particles with diameters of 10–30 μm. These particles had rough surfaces, which enhance light absorption through multi-scattering effects. The recycled dPVC remained as irregular particles with rough surfaces (Fig. 5b). Elemental mapping images obtained through X-ray energy dispersive spectroscopy (EDS) showed a uniform distribution of characteristic elements, indicating the PVC after chlorine transfer was primarily composed of carbon, retained a portion of chlorine, and introduced a small amount of oxygen (Fig. 5c). After participating in the depolymerization of PS under sunlight, chlorine element in dPVC was almost completely eliminated, while carbon and oxygen elements were retained (Fig. 5d). No chlorinated products were detected in the degradation products, and hardly any were generated even with the additional introduction of PVC (Supplementary Table 11). Moreover, given that the chlorine content in dPVC is extremely low relative to that of the recycled polyolefin plastics, the migration of residual chlorine from dPVC to the products is negligible. To further identify the chemical structures of the photothermal agent, 13C CP/MAS NMR was conducted on dPVC. As shown in Fig. 5e, a prominent signal corresponding to sp2 C was detected at 135 ppm, which suggested a significant presence of C=C bonds within dPVC. Additionally, dPVC exhibited strong signals indicative of sp3 C (57, 46 ppm), implying that not all hydrogen chloride in PVC was eliminated to form double bonds. This observation was further substantiated by Fourier transform infrared spectroscopy (FT-IR) analysis for investigation on the structural changes in dPVC after being used in depolymerization of polyolefins (Fig. 5f). The FT-IR spectra of dPVC and recycled dPVC both showed weak C(sp2)-H stretching vibrations from 3000-3050 cm-1 and corresponding bending vibrations in the range of 685-760 cm-1. In the FT-IR spectrum of dPVC, peaks at 2908 cm-1 and 1426 cm-1 represented the stretching and bending vibrations of C(sp3)-H, respectively, but these signals became very weak in the recycled dPVC. This indicated a transformation of C-H bonds in dPVC. With respect to C=C bonds stretching vibrations, the relative peak intensity at 1580-1600 cm-1 in the recycled dPVC was stronger compared to that in dPVC, indicating an increase in the number of double bonds in the recycled dPVC. Additionally, strong C-Cl bond stretching vibration (607 cm-1) was only detected in dPVC, further confirming the elimination of chlorine during the reaction, which resulted in the formation of more double bonds. Moreover, peaks at 1724 cm-1 ascribed to the stretching vibration of C=O and at 1240 cm-1 belonging to C-O stretching vibrations in both dPVC and recycled dPVC indicated that oxygen was bonded to carbon in the forms of C=O and C-O in dPVC. Raman spectrum was used to further characterize the chemical structure of the dPVC (Fig. 5g). The D band (at 1360 cm-1) and G band (at 1590 cm-1) reflected the sp3-hybridized amorphous carbon structure and sp2-hybridized C=C structure in dPVC respectively. Figure 5g presented that there were two bands within both samples, showing the occurred graphitization process from disordered structure to graphitic structure54,55. To investigate whether the graphitized dPVC possesses photocatalytic activity, its photocurrent response was tested. Under xenon lamp irradiation, the photocurrent of dPVC was extremely weak, which was much lower than that of graphitic carbon nitride (g-C3N4), a commonly used photocatalyst. Electrochemical impedance spectroscopy (EIS, Supplementary Fig. 57) demonstrated that dPVC exhibited a significantly higher charge transfer resistance compared to g-C3N4. Collectively, these results indicate that dPVC lacks efficient photocatalytic activity. Therefore, dPVC primarily functions as a photothermal conversion agent in the degradation of polyolefins.

Comparison of dPVC with other photothermal agents
Compared with some photothermal agents reported in the literature14,56, dPVC exhibit certain advantages in terms of efficiency, stability, or cost-effectiveness for polyolefin recycling. To verify this, the efficiency of PS conversion to styrene was compared in the presence of different photothermal agents under sunlight irradiation (Supplementary Table 8). Specifically, dPVC exhibited higher monomer generation efficiency than carbon black (CB). Carbon nanotubes (CNTs) showed comparable performance to dPVC, but their high cost limits practical applicability. Carbon quantum dots (CQDs) also effectively facilitated the conversion of PS to monomers. However, they exhibited poor stability at high temperatures, making them challenging to reuse. These experimental results collectively demonstrate that dPVC is an excellent photothermal reagent for polyolefin recycling. Furthermore, the synthesis process of dPVC enables the full utilization of PVC, and it can be used to recycle PVC-containing mixed waste plastics without generating large quantities of hydrogen chloride.

Methods
Synthesis of dPVC
Typically, 6-methoxy-2-acetylnaphthalene (2.14 g, 10.0 mmol), i-PrBr (188 μL, 2.0 mmol, 20 mol%), PVC (1.25 g, 20.0 mmol repeat unit, 2.0 equiv.), DMSO (10 mL) and DMF (90 mL) were added to a 250 mL round bottom flask equipped with a Teflon coated magnetic stir bar and a condenser. Under vigorous stirring, the reaction mixture was heated at 120 °C for 12 h. After cooling to room temperature, the yield of α-chloroketone was determined by HPLC analysis of the crude product mixture using naphthalene as internal standard, and then the reaction mixture was poured into 100 mL methanol while stirring to precipitate the polymer. The insoluble polymer was collected by filtration and then ultrasonically cleaned in 100 mL methanol, followed by filtration. This process was repeated until no more ketones were detected in the solution by TLC. Finally, the polymer was collected by filtration and dried under vacuum overnight. The mass of dPVC for this reaction was 900 mg (yield: 72 wt%). Prior to its use as a catalyst, dPVC should be ground for at least 5 minutes using a ceramic mortar.

Depolymerization of PP and PE
Typically, depolymerization of PP, PE and their post-consumer plastics under air is described as follows. The polyolefin (60.0 mg) and dPVC (6.0 mg, 10 wt%) powders were weighed into a 4 mL sample vial. The mixture was stirred with a metal spatula until a homogeneous color was achieved, and then transferred to a crucible (8 × 8 × 6 mm) (Supplementary Fig. 1c), which was then positioned inside a 25 mL round-bottom flask (Supplementary Fig. 1b) equipped with an air condenser and secured to an iron stand. A concave mirror with a diameter of 30 cm was used to concentrate sunlight (100-110 mW cm-2) onto the quartz crucible (Supplementary Fig. 1a). When only a small amount of black powder remained in the crucible, the light exposure ceased, marking the end of the reaction (Supplementary Fig. 1f). After cooling to room temperature, the white smoke dissipated, and waxy substances condensed on the walls of the flask and the condenser. The waxes were dissolved in hot petroleum ether, filtered to remove the dPVC, and the solvent was removed by rotary evaporation. The resulting product was vacuum dried.

Depolymerization of PS, PAMS, PMMA, SAN, and ABS
Typically, degradation of PS, PAMS, PMMA, SAN, ABS and post-consumer PS and PMMA plastics under air are described as follows. The polyolefin (1.0 mmol repeat unit), dPVC (10 wt%) and butylated hydroxytoluene (BHT, 10 mol%) powders were weighed into a 4 mL sample vial. The mixture was stirred with a metal spatula until a homogeneous color was achieved, and then transferred to a crucible (8*8*6 mm), which was then positioned inside a 25 mL round-bottom flask equipped with an air condenser and secured to an iron stand. A concave mirror with a diameter of 30 cm was used to concentrate sunlight (85-110 mW cm-2) onto the quartz crucible. When only a small amount of black powder remained in the crucible, the light exposure ceased, marking the end of the reaction. After cooling to room temperature, the crude products were dissolved in ethyl acetate (EA). The yields were determined by GC-FID analysis of the crude product mixture using mesitylene as internal standard.

Depolymerization of mixed post-consumer plastics
Depolymerization of mixed post-consumer plastics under air is described as follows. A sealed tube (15 mL) was charged with HDPE bucket (50.0 mg), LDPE bag (50.0 mg), PP food container (50.0 mg), PS cup (50.0 mg), PMMA sheet (50.0 mg), PVC glove (50.0 mg), 6-methoxy-2-acetyl naphthalene (42.9 mg, 0.20 mmol), i-PrBr (3.8 μL, 0.04 mmol, 20 mol%), DMSO (0.4 mL) and DMF (3.8 mL) at room temperature. The reaction tube was sealed with a Teflon screw cap. Then, the reaction mixture was stirred at 120 °C for 12 hours. After cooling to room temperature, the yield of α-chloroketone was determined by HPLC analysis of the crude product mixture using naphthalene as internal standard. Then, the reaction mixture was poured into 50 mL methanol while stirring to precipitate the polymer. The insoluble solid was collected by centrifugation (3700 × g, 6 min) and then ultrasonically cleaned in 50 mL of methanol, followed by centrifugation. This process was repeated until no more ketones were detected in the solution by TLC. Finally, the solid was collected by centrifugation and dried under vacuum overnight. The black solid was placed in a quartz crucible (10*10*10 mm), which was then positioned inside a 25 mL round-bottom flask equipped with an air condenser and secured to an iron stand. A concave mirror with a diameter of 30 cm was used to concentrate sunlight (113 mW cm-2) onto the quartz crucible When only a small amount of black powder remained in the crucible, the light exposure ceased, marking the end of the reaction.

Depolymerization of kilogram-scale PS plastic
The depolymerization scheme for kilogram-scale PS is as follows. The scheme employed a distillation setup and utilizes solar panels to power the condensation water circulation. 1.00 kg post-consumer PS (Mn, 116 kDa; Mw, 234 kDa) cups was pulverized, and then 200.00 g of the PS powder, along with 22.00 g of BHT and 1.00 g of dPVC made from PVC gloves, were mixed until a homogeneous color was achieved, and added to a 500 mL quartz three-necked flask. Under a nitrogen atmosphere and with continuous condensation water circulation, sunlight (111 mW cm-2) was concentrated at the bottom of the flask using a concave mirror with a diameter of 1.5 meters. The styrene generated was condensed in the condenser and collected. After the polymer in the flask had mostly disappeared, the light was paused (this process would take about 30 minutes), and after the flask cooled, 200.00 g of PS was added for reaction. This process was repeated until 1.00 kg of PS completely reacted. The yield of styrene was determined by 1H NMR analysis using 1,3,5-trimethoxybenzene as the internal standard.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "The manuscript by Chen and coworkers describes the sunlight-mediated recycling of polyolefins via the use of recycled\nPVC as the mediator. The idea is based on an earlier contribution, where PVC can be recycled via chlorination reaction with\na ketone. In the previous work, the chlorination reaction was of interest. Herein, the authors take the recycled PVC (black\nmaterial left from this reaction) and they use it as mediator for the sublight-mediated recycling of other polyolefins. The\nauthors highlight the recycling ability of PE and PP leading to mixtures of long alipahtic olefins, while PS, PAMS, PMMA are\nbeing converted into their monomers. The yields reported are extremely high. Real life plastic waste are being employed. A\nlarge scale is also demonstrated in the case of PS and this is the only case where the authors report the yield of the product\nafter isolation. In all other cases, GC or NMR yields are reported. Mechanistic studies are excellent. In total, this work can\nbecome suitable for publication, after some minor points are addressed. In more detail:\n1. SOme recent reviews on the photochemical upcycling of plastics should be added, like Trends in Chemistry, 2023, 5, 116,\nChem. Sci., 2024, 15, 1611, Green Chem., 2024, 26, 8528 and ACS Catal., 2024, 14 , 4865.\n2. Yield of isolated products or mixtures can be provided in some cases and not only in the large scale of PS", "reviewer_2": "This study presents an innovative protocol for upcycling waste PVC into a photothermal agent capable of depolymerizing\npolyolefins under solar irradiation. The derived dPVC material demonstrates excellent ability to convert sunlight into thermal\nenergy sufficient for cleaving C-C bonds in polyolefins. The proposed method successfully converts low-density\npolyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP) into terminal olefin-enriched waxes.\nMoreover, it shows promising results in depolymerizing polystyrene, poly(methyl methacrylate), poly(α-methyl styrene),\nstyrene-acrylonitrile copolymer, and acrylonitrile-butadiene-styrene into their respective monomers. This approach offers\nvaluable insights for chemical recycling of mixed plastics under ambient conditions. However, several critical issues need to\nbe addressed before acceptance:\n1. The manuscript should provide a clearer demonstration of dPVC’s advantages over other reported photothermal catalysts\n(e.g., J. Am. Chem. Soc. 2025, 147, 2822−2828) in terms of efficiency, stability, or cost-effectiveness.\n2. In Figure 4d, what exactly are the “dPVC” and “recycled dPVC” samples? The significant difference in their thermal\nstability requires more detailed explanation.\n3. Does dPVC function solely as a photothermal converter (providing thermal energy for pyrolysis), or does it also exhibit\ncatalytic activity (e.g., facilitating radical generation)? Additional mechanistic studies and discussion are needed to clarify\nthis important aspect.\n4. If the primary role of dPVC is thermal conversion, the homogeneity of its mixture with plastics becomes crucial. The\nmanuscript should address this mixing efficiency and its potential impact on reaction outcomes.\n5. Residual chlorine appears to persist in dPVC according to the data. The authors should investigate and discuss the\npotential migration of chlorine into recycled products and its implications.\n6. The TGA results indicate decomposition of both dPVC and recycled dPVC at high temperatures. Since the reaction\nexceeds 400°C (Fig. 4e), does each recycling cycle incur dPVC loss? The manuscript should clarify whether fresh dPVC\nsupplementation is required for repeated use.\n7. The experimental section requires more detailed information to ensure reproducibility and clarity. Specifically, the reaction\natmosphere (e.g., air, nitrogen, or other conditions) for different plastic depolymerization processes should be clearly stated.\nAdditionally, for experiments involving complex mixed plastics, the manuscript should provide more comprehensive\ndescriptions of the analytical methods used to characterize the resulting products, including specific techniques for product\nseparation, identification, and quantification. These details are crucial for readers to properly evaluate and replicate the\nreported work.\n8. Some figures appear duplicated between the main text and supporting information. These redundancies should be\neliminated to improve manuscript clarity."}, "author_response": "Response to Reviewer 1:\nThis reviewer recommended publication in Nature Communications after some minor revisions. We\nthank the reviewer's appreciation on our work, and we respond as below.\nComments: (1) Some recent reviews on the photochemical upcycling of plastics should be\nadded, like Trends in Chemistry, 2023, 5, 116, Chem. Sci., 2024, 15, 1611, Green Chem.,\n2024, 26, 8528 and ACS Catal., 2024, 14, 4865.\nResponse: We appreciate the reviewer’s suggestion. The reviews have been cited (Please see\nreferences 37, 41-43).\nComments: (2) Yield of isolated products or mixtures can be provided in some cases and\nnot only in the large scale of PS.\nResponse: We thank the reviewer for this suggestion. Currently, the yields of the degradation\nproducts of LDPE, HDPE, and PP reported in this paper are all isolated yields, and a supplementary\nnote regarding this point has been added in the manuscript (Please see Page 5, Paragraph 1, line 16;\nPage 8, Paragraph 1, lines 4-5). Considering that some polyolefin degradation products exhibit\nrelatively low boiling points, the isolated yields obtained from small-scale experiments may not be\nsufficiently accurate. Therefore, the product yields were determined via GC-FID analysis with an\ninternal standard in the original manuscript, which ensures higher accuracy of the yield data.\nFollowing the reviewers’ suggestions, an attempt was made to separate the degradation products of\nPS and PAMS using silica gel column chromatography. However, due to the relatively low boiling\npoint of styrene (145-146 °C), a portion of styrene is inevitably removed along with the solvent\nduring the solvent removal process, making it difficult to obtain reliable isolated yields for styrene.\nIn contrast, α-methylstyrene (boiling point: 165-169 °C) is less volatile than styrene. The isolated\nyields (64%, 66%, 66%) and corresponding isolation method of α-methylstyrene have been\nprovided in the Supplementary Information (Please see Page S17, Supplementary Table 2) and\nexplicitly annotated in the manuscript (Please see Page 7, Paragraph 1, line 5).\nResponse to Reviewer 2:\nThis reviewer recommended reconsideration for publication in Nature Communications after some\nrevisions. We thank the reviewer's appreciation on our work, and we respond as below.\nComments: (1) The manuscript should provide a clearer demonstration of dPVC’s\nadvantages over other reported photothermal catalysts (e.g., J. Am. Chem. Soc. 2025, 147,\n2822−2828) in terms of efficiency, stability, or cost-effectiveness.\nResponse: We thank the reviewer for this suggestion. We compared the efficiency of PS conversion\nto styrene in the presence of different photothermal reagents under sunlight irradiation (Please see\nSupplementary Information, Page S20, Supplementary Table 8). dPVC exhibited higher monomer\ngeneration efficiency than carbon black (CB, the catalyst reported in J. Am. Chem. Soc. 2025, 147,\n2822−2828). Carbon nanotubes (CNTs) showed comparable performance to dPVC, but their high\ncost limits practical application. Carbon quantum dots (CQDs, the catalyst reported in J. Am. Chem.\nSoc. 2023, 145, 16090-16097) also effectively promoted the conversion of PS to monomers.\nHowever, they posed challenges in recycling, as only a small amount of black coke remained in the\n1\ncrucible after the reaction (Please see Supplementary Information, Page S21, Supplementary Fig.\n21). These experimental results demonstrate that dPVC has certain advantages over some reported\nphotothermal catalysts in terms of efficiency, stability, and cost-effectiveness. Furthermore, we\nconsider that the most prominent advantage of dPVC over other photothermal reagents lies in the\nfact that it is synthesized using PVC as the raw material. This approach enables the conversion of\nPVC into high-value-added products. It can also avoid the difficult sorting tasks in plastic recycling\nand generating large amounts of hydrogen chloride when recycling PVC-containing mixed plastics,\npromoting the recovery of daily plastics.\nA statement: “Compared with some photothermal agents reported in the literature, dPVC exhibits\ncertain advantages in terms of efficiency, stability, or cost-effectiveness for polyolefin recycling. To\nverify this, the efficiency of PS conversion to styrene was compared in the presence of different\nphotothermal agents under sunlight irradiation (Supplementary Table 8). Specifically, dPVC\nexhibited higher monomer generation efficiency than carbon black (CB). Carbon nanotubes (CNTs)\nshowed comparable performance to dPVC, but their high cost limits practical applicability. Carbon\nquantum dots (CQDs) also effectively facilitated the conversion of PS to monomers. However, they\nexhibited poor stability at high temperatures, making them challenging to reuse. These experimental\nresults collectively demonstrate that dPVC is an excellent photothermal reagent for polyolefin\nrecycling. Furthermore, the synthesis process of dPVC enables the full utilization of PVC, and it\ncan be used to recycle PVC-containing mixed waste plastics without generating large quantities of\nhydrogen chloride.” was added in the manuscript (Please see Page 12, Paragraph 2).\nSupplementary Table 8. The yields of depolymerization of PS using different photothermal\nagents.\nEntry Photothermal agent Yield (%)[a]\n1 dPVC 65, 65, 66\nReaction conditions: PS (104.2 mg, 1.0 mmol repeat unit), photothermal agent (10.4 mg, 10 wt%),\nBHT (22.0 mg, 10 mol%), quartz crucible (8*8*6 mm), solar irradiance (100-107 mW/cm2),\nconcave mirror (diameter = 30 cm), irradiation time (~3 min), under air. [a]Determined by GC-FID\nwith mesitylene as the internal standard. CB = Carbon black. CNTs = Carbon nanotubes. CQDs =\nCarbon quantum dots.\nComments: (2) In Figure 4d, what exactly are the “dPVC” and “recycled dPVC”\nsamples? The significant difference in their thermal stability requires more detailed\nexplanation.\nResponse: We appreciate the reviewer’s suggestion. In Figure 4d, the “dPVC” refers to the\nphotothermal agent directly synthesized from PVC and “recycled dPVC” denotes the photothermal\nagent recycled after one cycle of use. To improve clarity and accuracy, we have added\ncorresponding annotations to “recycled dPVC” in the manuscript (Please see Page 8, Paragraph 3,\n2\nline 2; Page 10, Paragraph 1, line 4). Additionally, detailed descriptions of the preparation methods\nfor the two reagents have been provided in the Supplementary Information (Please see Page S38,\nSection 6.1; Page S39, Section 6.4). During the first application, dPVC was exposed to a\nhigh-temperature environment, which caused the removal of part of its residual chlorine. This\ndechlorination process renders “dPVC” less thermally stable than “recycled dPVC”. The\nsupplemented additional explanation about the stability of “recycled dPVC” was added in the\nmanuscript.\nA statement: “The enhanced thermal stability is presumably ascribed to the removal of residual\nchlorine in dPVC under solar irradiation. This chlorine elimination was confirmed in subsequent\nexperiments.” was added in the manuscript (Please see Page 10, Paragraph 1, lines 6-8).\nComments: (3) Does dPVC function solely as a photothermal converter (providing\nthermal energy for pyrolysis), or does it also exhibit catalytic activity (e.g., facilitating\nradical generation)? Additional mechanistic studies and discussion are needed to clarify\nthis important aspect.\nResponse: We appreciate the reviewer’s suggestion. In order to investigate whether dPVC can\nfacilitate radical generation under light irradiation, we first measured the photocurrent response of\ndPVC and compared it with that of graphitic carbon nitride (g-C N ), a commonly used\n3 4\nphotocatalyst. As shown in Supplementary Fig. 54, g-C N exhibited a distinct photocurrent under\n3 4\nxenon lamp irradiation, whereas the photocurrent of dPVC was extremely weak.\n0.10\n0.05\n0.00\n−0.05\n−0.10\n−0.15\n0 50 100 150 200\n3\n)Aμ(\ntnerrucotohP\ndPVC\non off\ng-C N\n3 4\nTime (S)\nSupplementary Fig. 54 Photocurrent responses of dPVC and g-C N\n3 4\nElectrochemical impedance spectroscopy (EIS, please see Supplementary Information, Page S47,\nSupplementary Fig. 55) revealed that dPVC possessed a significantly higher charge transfer\nresistance than g-C N . These results indicate that dPVC lacks efficient photocatalytic activity.\n3 4\nAccordingly, we propose that dPVC acts as a photothermal conversion agent in the degradation of\npolyolefins.\n3000\ndPVC\ng-C N\n2500 3 4\n2000\n1500\n1000\n500\n0\n0 1000 2000 3000 4000 5000 6000\n4\n)Ω(\n''Z\nZ' (Ω)\nSupplementary Fig. 55 Electrochemical impedance spectroscopy (EIS) Nyquist plot of dPVC\nand g-C N\n3 4\nA statement: “To investigate whether the graphitized dPVC possesses photocatalytic activity, its\nphotocurrent response was tested. Under xenon lamp irradiation, the photocurrent of dPVC was\nextremely weak, which was much lower than that of graphitic carbon nitride (g-C N ), a commonly\n3 4\nused photocatalyst. Electrochemical Impedance Spectroscopy (EIS, Supplementary Fig. 55)\ndemonstrated that dPVC exhibited a significantly higher charge transfer resistance compared to\ng-C N . Collectively, these results indicate that dPVC lacks efficient photocatalytic activity.\n3 4\nTherefore, dPVC primarily functions as a photothermal conversion agent in the degradation of\npolyolefins.” was added in the manuscript (Please see Page 12, Paragraph 1, lines 8-14).\nComments: (4) If the primary role of dPVC is thermal conversion, the homogeneity of its\nmixture with plastics becomes crucial. The manuscript should address this mixing\nefficiency and its potential impact on reaction outcomes.\nResponse: We thank the reviewer for this suggestion. To investigate the influence of mixing\nhomogeneity between dPVC and plastic on the experimental results, we examined the degradation\nefficiency of PS with different mixing methods (Please see Supplementary Information, Pages\nS21-S22, Supplementary Table 9). Without prior mixing, the PS degradation efficiency was\nsignificantly reduced (with the complete conversion of PS requiring 5-6 minutes), and the yield of\nstyrene was also markedly decrease, indicating that mixing homogeneity is indeed crucial to plastic\ndegradation efficiency. After simple stirring mixing, the styrene yield was notably enhanced. To\nachieve more homogeneous mixing, the reactants were subjected to sufficient grinding and mixing.\nHowever, the styrene yield did not show a further increase.\nSupplementary Table 9. The yields of depolymerization of PS using different mixing methods.\ndPVC (10 wt%)\nBHT (10 mol%)\nn Ph\nsunlight\nPh\nEntry Mixing methods Yield (%)[a]\nReaction conditions: PS (104.2 mg, 1.0 mmol repeat unit), dPVC (10.4 mg, 10 wt%), BHT (22.0\nmg, 10 mol%), quartz crucible (8*8*6 mm), solar irradiance (100 mW/cm2), concave mirror\n(diameter = 30 cm), irradiation time (~3 min), under air. [a]Determined by GC-FID with mesitylene\nas the internal standard. [b]Irradiation time (~6 min).\nWe hypothesize that this phenomenon is attributed to the melting and boiling processes of PS\nduring degradation, which enable homogeneous mixing of dPVC and PS. To verify this hypothesis,\nwe conducted degradation experiments using PS particles of different sizes (Please see\nSupplementary Information, Pages S22, Supplementary Table 10). Larger PS particles exhibit a\nsmaller contact area with dPVC, and thus their degradation efficiency is expected to be lower.\nHowever, PS particles of varying sizes had similar degradation efficiencies after mixing with dPVC.\nThese experimental results indicate that the melting and boiling processes during degradation may\nfacilitate sufficient mixing of plastic and dPVC. Thus, only simple stirring mixing is required for\ndPVC and plastic at the initial stage of the reaction.\nTable S10. The yields of depolymerization of PS particles with different sizes.\ndPVC (10 wt%)\nBHT (10 mol%)\nn Ph\nsunlight\nPh\nEntry Size of PS (mesh) Yield (%)[a]\n1 40-20 67, 67, 67\n2 20-10 67, 66, 66\n3 10-5 66, 65, 67\nReaction conditions: PS (104.2 mg, 1.0 mmol repeat unit), dPVC (10.4 mg, 10 wt%), BHT (22.0\nmg, 10 mol%), quartz crucible (8*8*6 mm), solar irradiance (105 mW/cm2), concave mirror\n(diameter = 30 cm), irradiation time (~3 min), under air. The reactants were mixed by stirring.\n[a]Determined by GC-FID with mesitylene as the internal standard.\nThe mixing method of dPVC and plastic has been described in detail in the Methods section of the\nmanuscript (Please see Pages 13-15) and the Supplementary Information (Please see Pages S6,\nParagraph 2, lines 1-3; Pages S17, Paragraph 1, lines 1-4; Pages S18, the last Paragraph, lines 2-3).\nauthors should investigate and discuss the potential migration of chlorine into recycled\nproducts and its implications.\nResponse: We thank the reviewer for this suggestion. The residual chlorine in dPVC had almost no\nimpact on the reaction. Although the chlorine content in dPVC decreases during plastic\ndepolymerization, no chlorinated products were detected in the plastic degradation products. To\ninvestigate whether the low chlorine dosage resulted in migrated chlorinated products below the\ninstrumental detection limit, we co-degraded PS and PVC (the raw material for dPVC synthesis)\nand subsequently detected chlorinated products (Please see Supplementary Information, Pages S22,\nSupplementary Table 11). When 0.1 equivalent of PVC was used, chlorinated products remained\nundetectable; even with 1 equivalent of PVC, the yield of chlorinated products was still below 1%.\nIt should be noted that this result appears inconsistent with the findings reported in the literature (J.\nAm. Chem. Soc. 2025, 147, 2822−2828). This discrepancy arises from the extremely short reaction\ntime and the dry, non-sealed system employed in our method. These experimental results indicate\nthat the residual chlorine in dPVC barely migrates into the recycled products.\nSupplementary Table 11. The yields of chlorinated products from the co-degradation of PS\nand PVC.\nEntry PVC (equiv.) Yield (%)[a]\n1 0 N.D., N.D., N.D.\n2 0.1 N.D., N.D., N.D.\n3 1.0 <1, <1, <1\nReaction conditions: PS (104.2 mg, 1.0 mmol repeat unit), PVC (0-1.0 mmol repeat unit), dPVC\n(10.4 mg, 10 wt%), BHT (22.0 mg, 10 mol%), quartz crucible (10*10*10 mm), solar irradiance\n(100 mW/cm2), concave mirror (diameter = 30 cm), irradiation time (~3 min), under air.\n[a]Determined by GC-FID with mesitylene as the internal standard.\nA statement: “No chlorinated products were detected in the degradation products, and hardly any\nwere generated even with the additional introduction of PVC (Supplementary Table 11). Moreover,\ngiven that the chlorine content in dPVC is extremely low relative to that of the recycled polyolefin\nplastics, the migration of residual chlorine from dPVC to the products is negligible.” was added in\nthe manuscript (Please see Page 10, Paragraph 2, lines 9-12).\nComments: (6) The TGA results indicate decomposition of both dPVC and recycled dPVC\nat high temperatures. Since the reaction exceeds 400°C (Fig. 4e), does each recycling\ncycle incur dPVC loss? The manuscript should clarify whether fresh dPVC\nsupplementation is required for repeated use.\nResponse: We thank the reviewer for this suggestion. To investigate whether dPVC undergoes\nsustained mass loss, the mass of dPVC after each cycle was monitored (Please see Supplementary\nInformation, Pages S40, Supplementary Table 18). During the first two PS depolymerization cycles,\ndPVC exhibited a decrease in mass. However, by the third depolymerization experiment, its mass\nalmost remained unchanged. No additional fresh dPVC was required for repeated use, and this has\nbeen clarified in the manuscript (Please see Page 10, Paragraph 1, lines 10-12).\nSupplementary Table 18. Mass change of dPVC during recycling tests.\nReaction cycle Mass of dPVC (mg)\n0 10.4 10.4 10.4\n1 8.9 8.8 8.2\n2 8.2 7.6 7.3\n3 8.1 7.6 7.1\nComments: (7) The experimental section requires more detailed information to ensure\nreproducibility and clarity. Specifically, the reaction atmosphere (e.g., air, nitrogen, or\nother conditions) for different plastic depolymerization processes should be clearly stated.\nAdditionally, for experiments involving complex mixed plastics, the manuscript should\nprovide more comprehensive descriptions of the analytical methods used to characterize\nthe resulting products, including specific techniques for product separation, identification,\nand quantification. These details are crucial for readers to properly evaluate and\nreplicate the reported work.\nResponse: We thank the reviewer for this suggestion. All polymer depolymerization experiments\nwere conducted under air atmosphere, except for the kilogram-scale PS depolymerization\nexperiment. Descriptions of the reaction atmosphere have been supplemented in the manuscript\n(Please see Pages 13-15, Methods section) and Supplementary Information (Please see Pages S6,\nParagraph 2, line 1; Pages S17, Paragraph 1, line 1; Pages S18, the last Paragraph, line 1). For\nexperiments involving complex mixed plastics, we have included detailed experimental procedures\nin the manuscript (Please see Page 14, depolymerization of mixed post-consumer plastics in the\nMethods section), and provided more detailed elaborations on product separation, identification,\nand quantification in the Supplementary Information (Please see Pages S34).\nComments: (8) Some figures appear duplicated between the main text and supporting\ninformation. These redundancies should be eliminated to improve manuscript clarity.\nResponse: We thank the reviewer for this suggestion. To improve the clarity of the manuscript, we\nhave removed the duplicate figures (Figures S42, S44, S45, and S46) in the Supplementary\nInformation that overlapped with those in the manuscript. Within the Supplementary Information,\nonly the detailed information on experimental procedures has been retained (Please see Pages\nS38-S39, Sections 6.1-6.4).\n7"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have tried to address all comments raised in the previous round of reviewing and the revised manuscript is\nsuitable for publication, after some minor points are addressed. In more detail:\n1. In references 26-33, the authors should add: Chem, 2022, 8, 2472, ACS Catal. 2021, 11, 9159–9167 and Green Chem.,\n2023,25, 4750.\n2. Legend of Figure 2, mL adn not ml", "reviewer_2": "All my concerns have been addressed. I recommend acceptance and publication of the manuscript in its current form."}, "author_response": "Response to Reviewer 1:\nThis reviewer recommended publication in Nature Communications after some revisions. We\ngratitude the reviewer's appreciation on our work and we respond to below.\nComments: (1) In references 26-33, the authors should add: Chem, 2022, 8, 2472, ACS\nCatal. 2021, 11, 9159–9167 and Green Chem., 2023,25, 4750.\nResponse: We appreciate the reviewer’s suggestion. The references have been cited. (Please see\nreferences 34-36)\nComments: (2) Legend of Figure 2, mL adn not ml.\nResponse: We thank the reviewer for this suggestion. The error in the Legend of Figure 2 has been\ncorrected.\nResponse to Reviewer 2:\nThis reviewer recommended publication in Nature Communications without further revisions. We\nthank the reviewer's appreciation on our work."}]

Decision letter