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A Thienothiophene-Based Olefin-Linked Covalent Organic Framework for the Metal-Free Photocatalytic Oxidative Coupling of Amines 用于胺类无金属光催化氧化偶联的噻吩基烯烃连接共价有机框架
IF 5.8 Q1 POLYMER SCIENCE Pub Date : 2025-02-15 DOI: 10.1021/acsmacrolett.4c00847
Bertha Lotsi, Aadarsh Sharma, Jared G. Doremus, Spencer T. Burton, Claudia Turro, Psaras L. McGrier
The oxidative coupling of amines is a useful way to prepare many diverse compounds for the pharmaceutical and chemical industries. Covalent organic frameworks (COFs), a crystalline class of porous polymers, have emerged as promising heterogeneous photocatalysts that can accomplish this transformation under metal-free conditions due to their excellent photochemical stability and tunable electronic properties. Herein, we report the optoelectronic and photocatalytic properties of an olefin-linked COF containing thienothiophene (TT) and 2,4,6-trimethyl-1,3,5-triazine (TMT) units. The TT-TMT-COF exhibited a narrow band gap with extended light absorption and excellent charge separation, making it useful for the oxidative coupling of various benzylamines. The TT-TMT-COF exhibited fast reaction times, excellent recyclability, and conversions as high as ∼99%. The reactivity of TT-TMT-COF was on par or significantly better than that of a few small molecule 2,4,6-tris((E)-2-(thieno[3,2-b]thiophen-2-yl)vinyl)-1,3,5-triazine (TT-TMT) and 2,4,6-tris((E)-2-(thiophen-2-yl)vinyl)-1,3,5-triazine (Thio-TMT) homogeneous catalytic systems containing similar functional units. This work further highlights the ability of the COF to perform useful and efficient catalytic transformations in a sustainable manner.
{"title":"A Thienothiophene-Based Olefin-Linked Covalent Organic Framework for the Metal-Free Photocatalytic Oxidative Coupling of Amines","authors":"Bertha Lotsi, Aadarsh Sharma, Jared G. Doremus, Spencer T. Burton, Claudia Turro, Psaras L. McGrier","doi":"10.1021/acsmacrolett.4c00847","DOIUrl":"https://doi.org/10.1021/acsmacrolett.4c00847","url":null,"abstract":"The oxidative coupling of amines is a useful way to prepare many diverse compounds for the pharmaceutical and chemical industries. Covalent organic frameworks (COFs), a crystalline class of porous polymers, have emerged as promising heterogeneous photocatalysts that can accomplish this transformation under metal-free conditions due to their excellent photochemical stability and tunable electronic properties. Herein, we report the optoelectronic and photocatalytic properties of an olefin-linked COF containing thienothiophene (TT) and 2,4,6-trimethyl-1,3,5-triazine (TMT) units. The TT-TMT-COF exhibited a narrow band gap with extended light absorption and excellent charge separation, making it useful for the oxidative coupling of various benzylamines. The TT-TMT-COF exhibited fast reaction times, excellent recyclability, and conversions as high as ∼99%. The reactivity of TT-TMT-COF was on par or significantly better than that of a few small molecule 2,4,6-tris((<i>E</i>)-2-(thieno[3,2-<i>b</i>]thiophen-2-yl)vinyl)-1,3,5-triazine (TT-TMT) and 2,4,6-tris((<i>E</i>)-2-(thiophen-2-yl)vinyl)-1,3,5-triazine (Thio-TMT) homogeneous catalytic systems containing similar functional units. This work further highlights the ability of the COF to perform useful and efficient catalytic transformations in a sustainable manner.","PeriodicalId":18,"journal":{"name":"ACS Macro Letters","volume":"24 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Helical Poly(quioxaline-2,3-diyl)-Based Poly(carboxylic acid)s as a Chiroptical Chemosensor for Detection and Quantification of Small Enantiomeric Imbalances of Chiral Amines in Water. 螺旋状聚(喹喔啉-2,3-二基)聚(羧酸)作为千光化学传感器,用于检测和定量水中手性胺的微小对映异构体失衡。
IF 5.1 Q1 POLYMER SCIENCE Pub Date : 2025-02-14 DOI: 10.1021/acsmacrolett.4c00814
Tomonori Yamawaki, Takuma Kuroda, Takeshi Yamamoto, Yuuya Nagata, Michinori Suginome

Achiral dynamic helical polymers, poly(quinoxaline-2,3-diyl)s (P1 and P2) bearing achiral carboxylic acid side chains, i.e., carboxymethoxymethyl (in P1) and carboxyethoxymethyl (in P2), with different polymerization degrees were synthesized. They exhibited induced circular dichroism (ICD) in the presence of chiral amines such as 1-phenylethylamine and nicotine, 1,2-amino alcohols such as valinol, leucinol, and prolinol, and the basic amino acid, arginine, in response to the induction of right- or left-handed helical conformation. The efficiency of helix induction depends on the compatibility of the structures of amines and polymers, with no clear structural correlation. The highly sensitive and formulated nature of ICD with the helical polymer-based poly(carboxylic acid)s allowed their use as CD-based sensors to detect and quantify minute imbalances of the enantiomeric excess of chiral molecules. We determined 0.2%-0.6% ee in the commercially available 1-phenylethylamine from three different suppliers, which have the label of "dl" or no indication of enantiopurity using P1 as a chemosensor.

{"title":"Helical Poly(quioxaline-2,3-diyl)-Based Poly(carboxylic acid)s as a Chiroptical Chemosensor for Detection and Quantification of Small Enantiomeric Imbalances of Chiral Amines in Water.","authors":"Tomonori Yamawaki, Takuma Kuroda, Takeshi Yamamoto, Yuuya Nagata, Michinori Suginome","doi":"10.1021/acsmacrolett.4c00814","DOIUrl":"https://doi.org/10.1021/acsmacrolett.4c00814","url":null,"abstract":"<p><p>Achiral dynamic helical polymers, poly(quinoxaline-2,3-diyl)s (<b>P1</b> and <b>P2</b>) bearing achiral carboxylic acid side chains, i.e., carboxymethoxymethyl (in <b>P1</b>) and carboxyethoxymethyl (in <b>P2</b>), with different polymerization degrees were synthesized. They exhibited induced circular dichroism (ICD) in the presence of chiral amines such as 1-phenylethylamine and nicotine, 1,2-amino alcohols such as valinol, leucinol, and prolinol, and the basic amino acid, arginine, in response to the induction of right- or left-handed helical conformation. The efficiency of helix induction depends on the compatibility of the structures of amines and polymers, with no clear structural correlation. The highly sensitive and formulated nature of ICD with the helical polymer-based poly(carboxylic acid)s allowed their use as CD-based sensors to detect and quantify minute imbalances of the enantiomeric excess of chiral molecules. We determined 0.2%-0.6% ee in the commercially available 1-phenylethylamine from three different suppliers, which have the label of \"<i>dl</i>\" or no indication of enantiopurity using <b>P1</b> as a chemosensor.</p>","PeriodicalId":18,"journal":{"name":"ACS Macro Letters","volume":" ","pages":"272-277"},"PeriodicalIF":5.1,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143412307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Scaling Behavior of Entanglement Dynamics in Polyelectrolyte Solutions: Insights from High-Frequency Rheometry
IF 5.8 Q1 POLYMER SCIENCE Pub Date : 2025-02-13 DOI: 10.1021/acsmacrolett.4c00722
Yahya Rharbi
Entanglement dynamics in polyelectrolyte solutions remain a challenging topic, particularly in capturing the entire dynamic spectrum, from single entanglement relaxation (τe) to reptation time (τrep), and aligning these observations with scaling predictions in the semidilute entangled (SE) and fully entangled (FE) neutral regimes. Using piezo compressional and classic rotational rheometry, we investigate the scaling behaviors of key viscoelastic properties over several decades of time scales in ten million Mw cationic polyacrylamide solutions. Specific viscosity (ηsp) and τrep scale as predicted within Fuoss, SE, and FE regimes, defining crossover concentrations between these regimes (Ce and CD). More importantly, τe, the rubbery plateau width (τrepe), and the high-frequency modulus (Ge) scale as C–1.14±0.02, C1.25±0.07, and C1.32±0.05, aligning with SE prediction in the early SE regime before transitioning to neutral scaling of C–2.7±0.14, C3.1±0.15, and C2.35±0.07 at an intermediate concentration between Ce and CD labeled CDe. These results indicate that electrostatic interactions affect single entanglements and reptation differently, leading to a transition to neutral behavior at CDe for the former and at CD for the latter.
{"title":"Scaling Behavior of Entanglement Dynamics in Polyelectrolyte Solutions: Insights from High-Frequency Rheometry","authors":"Yahya Rharbi","doi":"10.1021/acsmacrolett.4c00722","DOIUrl":"https://doi.org/10.1021/acsmacrolett.4c00722","url":null,"abstract":"Entanglement dynamics in polyelectrolyte solutions remain a challenging topic, particularly in capturing the entire dynamic spectrum, from single entanglement relaxation (τ<sub>e</sub>) to reptation time (τ<sub>rep</sub>), and aligning these observations with scaling predictions in the semidilute entangled (SE) and fully entangled (FE) neutral regimes. Using piezo compressional and classic rotational rheometry, we investigate the scaling behaviors of key viscoelastic properties over several decades of time scales in ten million Mw cationic polyacrylamide solutions. Specific viscosity (η<sub>sp</sub>) and τ<sub>rep</sub> scale as predicted within Fuoss, SE, and FE regimes, defining crossover concentrations between these regimes (<i>C</i><sub>e</sub> and <i>C</i><sub>D</sub>). More importantly, τ<sub>e</sub>, the rubbery plateau width (τ<sub>rep</sub>/τ<sub>e</sub>), and the high-frequency modulus (<i>G</i><sub>e</sub>) scale as <i>C</i><sup>–1.14±0.02</sup>, <i>C</i><sup>1.25±0.07</sup>, and <i>C</i><sup>1.32±0.05</sup>, aligning with SE prediction in the early SE regime before transitioning to neutral scaling of <i>C</i><sup>–2.7±0.14</sup>, <i>C</i><sup>3.1±0.15</sup>, and <i>C</i><sup>2.35±0.07</sup> at an intermediate concentration between <i>C</i><sub>e</sub> and <i>C</i><sub>D</sub> labeled <i>C</i><sub>D</sub><sup>e</sup>. These results indicate that electrostatic interactions affect single entanglements and reptation differently, leading to a transition to neutral behavior at <i>C</i><sub><i>D</i></sub><sup>e</sup> for the former and at <i>C</i><sub>D</sub> for the latter.","PeriodicalId":18,"journal":{"name":"ACS Macro Letters","volume":"59 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Retraction of “Temperature-Controlled Star-Shaped Cellulose Nanocrystal Assemblies Resulting from Asymmetric Polymer Grafting”
IF 5.8 Q1 POLYMER SCIENCE Pub Date : 2025-02-13 DOI: 10.1021/acsmacrolett.4c00787
Fangbo Lin, Fabrice Cousin, Jean-Luc Putaux, Bruno Jean
The authors, Fabrice Cousin, Jean-Luc Putaux, and Bruno Jean, retract this article (DOI: 10.1021/acsmacrolett.8b01005) due to significant concerns regarding the integrity and reliability of the data presented. Specifically, the TEM images in the article show signs of manipulation, including the presence of repeated fragments and the use of the clone stamp tool applied with some image editing software. These issues compromise the validity of the main conclusions drawn in the study. The first author of the article, Fangbo Lin, was also contacted regarding the issue but did not reply. The original Letter was published on March 11, 2019, and retracted on February 13, 2025. This article has not yet been cited by other publications.
{"title":"Retraction of “Temperature-Controlled Star-Shaped Cellulose Nanocrystal Assemblies Resulting from Asymmetric Polymer Grafting”","authors":"Fangbo Lin, Fabrice Cousin, Jean-Luc Putaux, Bruno Jean","doi":"10.1021/acsmacrolett.4c00787","DOIUrl":"https://doi.org/10.1021/acsmacrolett.4c00787","url":null,"abstract":"The authors, Fabrice Cousin, Jean-Luc Putaux, and Bruno Jean, retract this article (DOI: 10.1021/acsmacrolett.8b01005) due to significant concerns regarding the integrity and reliability of the data presented. Specifically, the TEM images in the article show signs of manipulation, including the presence of repeated fragments and the use of the clone stamp tool applied with some image editing software. These issues compromise the validity of the main conclusions drawn in the study. The first author of the article, Fangbo Lin, was also contacted regarding the issue but did not reply. The original Letter was published on March 11, 2019, and retracted on February 13, 2025. This article has not yet been cited by other publications.","PeriodicalId":18,"journal":{"name":"ACS Macro Letters","volume":"63 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Pure Organic Thermally Activated Delayed Fluorescence Afterglow Polymers via Dopant Isomerization.
IF 5.1 Q1 POLYMER SCIENCE Pub Date : 2025-02-13 DOI: 10.1021/acsmacrolett.4c00818
Guanyu Liu, Zixin Yan, Qi Song, Qikun Sun, Shanfeng Xue, Wenjun Yang

N-(o-Cyanophenyl)carbazole can be dimerized at different positions, which may change excited state behaviors. Herein, 2,3'-dicyano-3,4'-di(carbazol-9-yl)biphenyl (D34C) is designed and synthesized and doped into polymers. However, we find that D34C does not exhibit room temperature phosphorescence but emits fluorescence (FL) and bright thermally activated delayed fluorescence (TADF) with lifetimes of hundreds of milliseconds, which is observed in diverse matrices such as PMMA, MBS, ABS, PS, HIPS, and SIS. The simple positional isomerization makes the abundant triplet excitons undergo only reverse intersystem crossing rather than room temperature phosphorescence (RTP) radiation, which is rather rare in organic doped polymers. Since the production of TADF afterglow requires a certain excitation time, the generally indistinguishable FL and TADF efficiencies are separated for the first time. This work not only provides novel TADF afterglow polymers with diverse mechanical properties but also will evoke the subtle design of conjugated organic molecules to dramatically change photoexcitation and emission behaviors.

{"title":"Pure Organic Thermally Activated Delayed Fluorescence Afterglow Polymers via Dopant Isomerization.","authors":"Guanyu Liu, Zixin Yan, Qi Song, Qikun Sun, Shanfeng Xue, Wenjun Yang","doi":"10.1021/acsmacrolett.4c00818","DOIUrl":"https://doi.org/10.1021/acsmacrolett.4c00818","url":null,"abstract":"<p><p><i>N</i>-(<i>o</i>-Cyanophenyl)carbazole can be dimerized at different positions, which may change excited state behaviors. Herein, 2,3'-dicyano-3,4'-di(carbazol-9-yl)biphenyl (D34C) is designed and synthesized and doped into polymers. However, we find that D34C does not exhibit room temperature phosphorescence but emits fluorescence (FL) and bright thermally activated delayed fluorescence (TADF) with lifetimes of hundreds of milliseconds, which is observed in diverse matrices such as PMMA, MBS, ABS, PS, HIPS, and SIS. The simple positional isomerization makes the abundant triplet excitons undergo only reverse intersystem crossing rather than room temperature phosphorescence (RTP) radiation, which is rather rare in organic doped polymers. Since the production of TADF afterglow requires a certain excitation time, the generally indistinguishable FL and TADF efficiencies are separated for the first time. This work not only provides novel TADF afterglow polymers with diverse mechanical properties but also will evoke the subtle design of conjugated organic molecules to dramatically change photoexcitation and emission behaviors.</p>","PeriodicalId":18,"journal":{"name":"ACS Macro Letters","volume":" ","pages":"265-271"},"PeriodicalIF":5.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143412308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Autophagy-Activating Nanoautophagosome-Tethering Compounds for Targeted Protein Degradation Specifically in Tumor Cells
IF 5.8 Q1 POLYMER SCIENCE Pub Date : 2025-02-11 DOI: 10.1021/acsmacrolett.4c00789
Mengchen Xu, Jiajing Chen, Shuyu Wang, Linlin Xu, Xiaohui Wu, Jinpu Yu, Feihe Ma, Linqi Shi
Autophagosome-tethering compounds (ATTECs) represent an emerging targeted protein degradation (TPD) technology that directly draws intracellular proteins of interest (POIs) into autolysosomes. Although ATTECs are currently dominated by small molecules, the poor cell-type specificity and pharmacokinetic profile limit their applications in certain diseases. Moreover, the suboptimal intrinsic autophagic activity of cells affects the ATTECs-mediated degradation capability. Here we develop a nano-ATTEC system using our unique mixed-shell polymeric micelle (MSPM)-based nanoplatform for tumor-specific degradation of POIs. We demonstrate that the MSPMs-based nano-ATTEC is efficiently taken up by tumor cells in the acidic tumor microenvironment and to degrade POIs, rather than by normal cells under physiological conditions. More importantly, we find that this nano-ATTEC can not only target autolysosomes but also robustly enhance the autophagy activity, thereby establishing a positive feedback mechanism based on the autophagy pathway for efficient degradation of POIs. We believe that this MSPMs-based nano-ATTEC will find broad applications in tumor therapy.
{"title":"Autophagy-Activating Nanoautophagosome-Tethering Compounds for Targeted Protein Degradation Specifically in Tumor Cells","authors":"Mengchen Xu, Jiajing Chen, Shuyu Wang, Linlin Xu, Xiaohui Wu, Jinpu Yu, Feihe Ma, Linqi Shi","doi":"10.1021/acsmacrolett.4c00789","DOIUrl":"https://doi.org/10.1021/acsmacrolett.4c00789","url":null,"abstract":"Autophagosome-tethering compounds (ATTECs) represent an emerging targeted protein degradation (TPD) technology that directly draws intracellular proteins of interest (POIs) into autolysosomes. Although ATTECs are currently dominated by small molecules, the poor cell-type specificity and pharmacokinetic profile limit their applications in certain diseases. Moreover, the suboptimal intrinsic autophagic activity of cells affects the ATTECs-mediated degradation capability. Here we develop a nano-ATTEC system using our unique mixed-shell polymeric micelle (MSPM)-based nanoplatform for tumor-specific degradation of POIs. We demonstrate that the MSPMs-based nano-ATTEC is efficiently taken up by tumor cells in the acidic tumor microenvironment and to degrade POIs, rather than by normal cells under physiological conditions. More importantly, we find that this nano-ATTEC can not only target autolysosomes but also robustly enhance the autophagy activity, thereby establishing a positive feedback mechanism based on the autophagy pathway for efficient degradation of POIs. We believe that this MSPMs-based nano-ATTEC will find broad applications in tumor therapy.","PeriodicalId":18,"journal":{"name":"ACS Macro Letters","volume":"9 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
High Carbon Recovery in Photocatalytic Degradation of High-Density Polyethylene (HDPE): Blend with Stearic Acid as a Radical Source
IF 5.8 Q1 POLYMER SCIENCE Pub Date : 2025-02-10 DOI: 10.1021/acsmacrolett.4c00726
Bin Lu, Kohei Takahashi, Kyoko Nozaki
A blend of high-density polyethylene (HDPE, Mw = 59.4 kDa) and stearic acid was efficiently degraded under cerium catalyzed photodecarboxylation conditions, and the molecular weight decreased to Mw = ∼5 kDa. The reaction proceeds at 100 °C in tert-butylnitrile (tBuCN) in air, where HDPE does not dissolve or swell. The products are solid material with >90% weight recovery of the starting HDPE + stearic acid. Control experiments supported that carbon radicals generated by cerium-catalyzed photodecarboxylation of stearic acid transferred to the main chain of the HDPE, which undergoes oxidative degradation to lower the molecular weight.
{"title":"High Carbon Recovery in Photocatalytic Degradation of High-Density Polyethylene (HDPE): Blend with Stearic Acid as a Radical Source","authors":"Bin Lu, Kohei Takahashi, Kyoko Nozaki","doi":"10.1021/acsmacrolett.4c00726","DOIUrl":"https://doi.org/10.1021/acsmacrolett.4c00726","url":null,"abstract":"A blend of high-density polyethylene (HDPE, <i>M</i><sub>w</sub> = 59.4 kDa) and stearic acid was efficiently degraded under cerium catalyzed photodecarboxylation conditions, and the molecular weight decreased to <i>M</i><sub>w</sub> = ∼5 kDa. The reaction proceeds at 100 °C in <i>tert</i>-butylnitrile (<sup><i>t</i></sup>BuCN) in air, where HDPE does not dissolve or swell. The products are solid material with &gt;90% weight recovery of the starting HDPE + stearic acid. Control experiments supported that carbon radicals generated by cerium-catalyzed photodecarboxylation of stearic acid transferred to the main chain of the HDPE, which undergoes oxidative degradation to lower the molecular weight.","PeriodicalId":18,"journal":{"name":"ACS Macro Letters","volume":"62 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Ultrafast Thermal RAFT Depolymerization at Higher Solid Contents
IF 5.8 Q1 POLYMER SCIENCE Pub Date : 2025-02-10 DOI: 10.1021/acsmacrolett.5c00009
Dimitra Mantzara, Richard Whitfield, Hyun Suk Wang, Nghia P. Truong, Athina Anastasaki
Although thermal solution RAFT depolymerization has recently emerged as an efficient chemical recycling methodology, current approaches require specialized solvents (i.e., dioxane), typically suffer from extended reaction times, and operate exclusively under highly dilute conditions (i.e., 5 mM repeat unit concentration). To circumvent these limitations, a commercial radical initiator is introduced to kinetically untrap the depolymerization and promote chain-end activation. By varying the initiator concentration, a remarkable rate acceleration (up to 72 times faster) can be observed, enabling the completion of the depolymerization within 5 min. Notably, a 20-fold increase in the repeat unit concentration did not appreciably compromise the final depolymerization yield, while very high percentages of monomer could be recovered in a wide range of solvents, including dimethyl sulfoxide, anisole, xylene, acetonitrile, toluene, and trichlorobenzene. Our findings not only offer intriguing mechanistic aspects, but also significantly expand the scope and applications of thermal RAFT depolymerization.
{"title":"Ultrafast Thermal RAFT Depolymerization at Higher Solid Contents","authors":"Dimitra Mantzara, Richard Whitfield, Hyun Suk Wang, Nghia P. Truong, Athina Anastasaki","doi":"10.1021/acsmacrolett.5c00009","DOIUrl":"https://doi.org/10.1021/acsmacrolett.5c00009","url":null,"abstract":"Although thermal solution RAFT depolymerization has recently emerged as an efficient chemical recycling methodology, current approaches require specialized solvents (i.e., dioxane), typically suffer from extended reaction times, and operate exclusively under highly dilute conditions (i.e., 5 mM repeat unit concentration). To circumvent these limitations, a commercial radical initiator is introduced to kinetically untrap the depolymerization and promote chain-end activation. By varying the initiator concentration, a remarkable rate acceleration (up to 72 times faster) can be observed, enabling the completion of the depolymerization within 5 min. Notably, a 20-fold increase in the repeat unit concentration did not appreciably compromise the final depolymerization yield, while very high percentages of monomer could be recovered in a wide range of solvents, including dimethyl sulfoxide, anisole, xylene, acetonitrile, toluene, and trichlorobenzene. Our findings not only offer intriguing mechanistic aspects, but also significantly expand the scope and applications of thermal RAFT depolymerization.","PeriodicalId":18,"journal":{"name":"ACS Macro Letters","volume":"23 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
High Carbon Recovery in Photocatalytic Degradation of High-Density Polyethylene (HDPE): Blend with Stearic Acid as a Radical Source
IF 5.1 Q1 POLYMER SCIENCE Pub Date : 2025-02-10 DOI: 10.1021/acsmacrolett.4c0072610.1021/acsmacrolett.4c00726
Bin Lu, Kohei Takahashi* and Kyoko Nozaki*, 

A blend of high-density polyethylene (HDPE, Mw = 59.4 kDa) and stearic acid was efficiently degraded under cerium catalyzed photodecarboxylation conditions, and the molecular weight decreased to Mw = ∼5 kDa. The reaction proceeds at 100 °C in tert-butylnitrile (tBuCN) in air, where HDPE does not dissolve or swell. The products are solid material with >90% weight recovery of the starting HDPE + stearic acid. Control experiments supported that carbon radicals generated by cerium-catalyzed photodecarboxylation of stearic acid transferred to the main chain of the HDPE, which undergoes oxidative degradation to lower the molecular weight.

{"title":"High Carbon Recovery in Photocatalytic Degradation of High-Density Polyethylene (HDPE): Blend with Stearic Acid as a Radical Source","authors":"Bin Lu,&nbsp;Kohei Takahashi* and Kyoko Nozaki*,&nbsp;","doi":"10.1021/acsmacrolett.4c0072610.1021/acsmacrolett.4c00726","DOIUrl":"https://doi.org/10.1021/acsmacrolett.4c00726https://doi.org/10.1021/acsmacrolett.4c00726","url":null,"abstract":"<p >A blend of high-density polyethylene (HDPE, <i>M</i><sub>w</sub> = 59.4 kDa) and stearic acid was efficiently degraded under cerium catalyzed photodecarboxylation conditions, and the molecular weight decreased to <i>M</i><sub>w</sub> = ∼5 kDa. The reaction proceeds at 100 °C in <i>tert</i>-butylnitrile (<sup><i>t</i></sup>BuCN) in air, where HDPE does not dissolve or swell. The products are solid material with &gt;90% weight recovery of the starting HDPE + stearic acid. Control experiments supported that carbon radicals generated by cerium-catalyzed photodecarboxylation of stearic acid transferred to the main chain of the HDPE, which undergoes oxidative degradation to lower the molecular weight.</p>","PeriodicalId":18,"journal":{"name":"ACS Macro Letters","volume":"14 2","pages":"231–234 231–234"},"PeriodicalIF":5.1,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Mechanochromic Break Points Control the Toughness of Entangled Polyphenylenes
IF 5.8 Q1 POLYMER SCIENCE Pub Date : 2025-02-10 DOI: 10.1021/acsmacrolett.4c00810
Annina Missikewitsch, Hartmut Komber, Till Biskup, Michael Sommer
Toughness engineering of a kinked polyphenylene (PmmpP) is demonstrated by using mechanochromic molecular break points. Varying amounts of thermally stable yet mechanically labile difluorenylsuccinonitrile (DFSN) motifs incorporated into PmmpP allow to largely tune mechanical failure of the specimen. While strain at break values of pristine PmmpP reach up to 300%, an increasing concentration of DFSN break points leads to a strongly decreasing and predictable strain at break. Homolytic bond scission of DFSN and formation of colored DFSN radicals is characterized by in situ UV–vis spectroscopy, which allows us to discern regions of necking and strain hardening during tensile testing. The formation and lifetime of radicals is further probed by EPR spectroscopy, suggesting reversibility of bond scission and thus the possibility to design tough materials with predicted failure and self-healing properties.
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ACS Macro Letters
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