Thermosetting epoxy resins are widely used in our society for adhesives, electronic devices, and building materials owing to their hardness and chemical stability; however, their robustness hinders their ability to chemically degrade to monomers and related low-molecular-weight molecules. Herein, we report the degradation of various thermosetting epoxy resins prepared from bisphenol A diglycidyl ether as a typical epoxy agent and various curing agents, such as diamino arenes, dithiols, and acid anhydrides. The degradation proceeded smoothly when sodium tert-butoxide was used as an activator in a 1,3-dimethyl-2-imidazolidinone solvent at 150 °C to form bisphenol A as a monomer precursor in high yields without any pretreatment. The proposed degradation method was successfully applied to cross-linked thermosetting epoxy resins derived from 4,4’-diaminodiphenylsulfone, a heat-resistant curing agent, commercially available adhesives, and carbon fiber-reinforced composite materials. When composite materials are used, the carbon fibers can be recovered intact. The degradation of various thermosetting epoxy resins prepared from bisphenol A diglycidyl ether as a typical epoxy agent and various curing agents, such as diamino arenes, dithiols, and acid anhydrides proceeded smoothly with sodium tert-butoxide in 1,3-dimethyl-2-imidazolidinone (DMI) solvent at 150 °C to form bisphenol A in high yields. Amide solvents effectively promoted depolymerization and allowed insoluble cross-linked thermosetting epoxy resins to undergo the reaction.
{"title":"Degradation of stable thermosetting epoxy resins mediated by bases in amide solvents","authors":"Yasunori Minami, Tomoo Tsuyuki, Hayato Ishikawa, Yoshihiro Shimoyama, Kazuhiko Sato, Masaru Yoshida","doi":"10.1038/s41428-024-00979-6","DOIUrl":"10.1038/s41428-024-00979-6","url":null,"abstract":"Thermosetting epoxy resins are widely used in our society for adhesives, electronic devices, and building materials owing to their hardness and chemical stability; however, their robustness hinders their ability to chemically degrade to monomers and related low-molecular-weight molecules. Herein, we report the degradation of various thermosetting epoxy resins prepared from bisphenol A diglycidyl ether as a typical epoxy agent and various curing agents, such as diamino arenes, dithiols, and acid anhydrides. The degradation proceeded smoothly when sodium tert-butoxide was used as an activator in a 1,3-dimethyl-2-imidazolidinone solvent at 150 °C to form bisphenol A as a monomer precursor in high yields without any pretreatment. The proposed degradation method was successfully applied to cross-linked thermosetting epoxy resins derived from 4,4’-diaminodiphenylsulfone, a heat-resistant curing agent, commercially available adhesives, and carbon fiber-reinforced composite materials. When composite materials are used, the carbon fibers can be recovered intact. The degradation of various thermosetting epoxy resins prepared from bisphenol A diglycidyl ether as a typical epoxy agent and various curing agents, such as diamino arenes, dithiols, and acid anhydrides proceeded smoothly with sodium tert-butoxide in 1,3-dimethyl-2-imidazolidinone (DMI) solvent at 150 °C to form bisphenol A in high yields. Amide solvents effectively promoted depolymerization and allowed insoluble cross-linked thermosetting epoxy resins to undergo the reaction.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 2","pages":"149-162"},"PeriodicalIF":2.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-00979-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1038/s41428-024-00972-z
Aiichiro Nagaki, Yosuke Ashikari
This focus review describes advancements in anionic polymerization achieved using flow microreactors. Anionic polymerization using traditional flask chemistry often requires extremely low temperatures and complex setups; thus, it is unsuitable for large-scale production. Flow microreactors, with features such as precise temperature control, rapid mixing, and precise time control, can overcome these limitations. Using these microreactors, otherwise impossible polymer synthesis reactions can occur, and a controlled molecular weight distribution and high reaction selectivity is attained. Due to the ability to perform reactions at high temperatures without excessive cooling, this method is environmentally friendly and cost-effective. Additionally, precise time control allows the use of highly unstable polymer chain ends and functionalized alkyllithiums for further reactions, facilitating the synthesis of heterotelechelic polymers. Similar to those in laboratory-scale experiments, the continuous operation of the flow microreactors can be used to scale up the reaction under conditions, demonstrating their potential for industrial applications. This focus review highlights the significant contributions of flow microreactors to polymer production and facilitates future advancements in high-speed, environmentally benign polymer synthesis. Our recent studies on the anionic polymerization achieved using flow microreactors are reviewed. Using flow microreactors, with features such as precise temperature control, rapid mixing, and precise time control, otherwise impossible polymer synthesis reactions can occur. Some typical examples synthesizing polymers with reactive functional groups and heterotelechelic polymers are described. This review also highlights the in-line analyses of the polymer living end, helping a deeper insights of the reaction and its conditions. The continuous operation of the flow microreactors demonstrated their potential for industrial applications.
{"title":"Anionic polymerization driven by flow microchemistry","authors":"Aiichiro Nagaki, Yosuke Ashikari","doi":"10.1038/s41428-024-00972-z","DOIUrl":"10.1038/s41428-024-00972-z","url":null,"abstract":"This focus review describes advancements in anionic polymerization achieved using flow microreactors. Anionic polymerization using traditional flask chemistry often requires extremely low temperatures and complex setups; thus, it is unsuitable for large-scale production. Flow microreactors, with features such as precise temperature control, rapid mixing, and precise time control, can overcome these limitations. Using these microreactors, otherwise impossible polymer synthesis reactions can occur, and a controlled molecular weight distribution and high reaction selectivity is attained. Due to the ability to perform reactions at high temperatures without excessive cooling, this method is environmentally friendly and cost-effective. Additionally, precise time control allows the use of highly unstable polymer chain ends and functionalized alkyllithiums for further reactions, facilitating the synthesis of heterotelechelic polymers. Similar to those in laboratory-scale experiments, the continuous operation of the flow microreactors can be used to scale up the reaction under conditions, demonstrating their potential for industrial applications. This focus review highlights the significant contributions of flow microreactors to polymer production and facilitates future advancements in high-speed, environmentally benign polymer synthesis. Our recent studies on the anionic polymerization achieved using flow microreactors are reviewed. Using flow microreactors, with features such as precise temperature control, rapid mixing, and precise time control, otherwise impossible polymer synthesis reactions can occur. Some typical examples synthesizing polymers with reactive functional groups and heterotelechelic polymers are described. This review also highlights the in-line analyses of the polymer living end, helping a deeper insights of the reaction and its conditions. The continuous operation of the flow microreactors demonstrated their potential for industrial applications.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 2","pages":"143-148"},"PeriodicalIF":2.3,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1038/s41428-024-00982-x
Wenda Wang, Qiang Wang, Ping Wang
Acrylic acid (AA)/methyl acrylate (MA)-modified starch was prepared via a catalytic process involving horseradish peroxidase (HRP)/acetylacetone (ACAC) as an initiation system. The structural analysis results demonstrated that the grafting of AA and MA onto starch was successful. Furthermore, the impact of the grafting reaction conditions on the grafting effect and the characteristics of the resulting grafted products were also examined. The results demonstrated that AA and MA were successfully grafted onto starch. The optimal conditions for starch grafting with AA/MA were identified as a reaction time of 4 h, an HRP enzyme concentration of 12 U/mL, a total monomer/starch ratio of 4:6, and a molar ratio of AA/MA feeding of 3:7. The viscosity and viscoelasticity of the modified starch slurry increased, and the film-forming property was enhanced. Compared with the original starch film, the modified film markedly increased the flexibility and tensile strength. Furthermore, an increased acrylic acid content maintained the original hydrophilicity of the modified starch film. The horseradish peroxidase (HRP)/acetone peroxide (ACAC) binary system serves as an initiator to stimulate the generation of free radicals from starch, acrylic acid (AA), and methyl acrylate (MA). Simultaneously, while AA and MA undergo self-polymerization and copolymerization, they also get grafted onto starch chains through self-polymerization and alternating copolymerization. A substantial number of branched small-molecule chains are uniformly grafted onto the primary chain of starch with a low molecular weight.
以辣根过氧化物酶（HRP）/乙酰丙酮（ACAC）为引发体系，通过催化过程制备了丙烯酸（AA）/丙烯酸甲酯（MA）改性淀粉。结构分析结果表明 AA 和 MA 成功接枝到淀粉上。此外，还考察了接枝反应条件对接枝效果的影响以及接枝产物的特性。结果表明，AA 和 MA 成功地接枝到了淀粉上。确定了 AA/MA 接枝淀粉的最佳条件为：反应时间为 4 h，HRP 酶浓度为 12 U/mL，总单体/淀粉比为 4:6，AA/MA 进料摩尔比为 3:7。改性后的淀粉浆粘度和粘弹性增加，成膜性能提高。与原始淀粉薄膜相比，改性薄膜明显提高了柔韧性和拉伸强度。此外，丙烯酸含量的增加还保持了改性淀粉薄膜原有的亲水性。辣根过氧化物酶（HRP）/过氧化丙酮（ACAC）二元体系可作为引发剂，刺激淀粉、丙烯酸（AA）和丙烯酸甲酯（MA）产生自由基。与此同时，当 AA 和 MA 发生自聚合和共聚合时，它们也会通过自聚合和交替共聚合接枝到淀粉链上。大量支化的小分子链均匀地接枝到分子量较低的淀粉主链上。
{"title":"Research on the preparation and performance of acrylic acid/methyl acrylate-modified starch catalyzed by an HRP binary initiation system","authors":"Wenda Wang, Qiang Wang, Ping Wang","doi":"10.1038/s41428-024-00982-x","DOIUrl":"10.1038/s41428-024-00982-x","url":null,"abstract":"Acrylic acid (AA)/methyl acrylate (MA)-modified starch was prepared via a catalytic process involving horseradish peroxidase (HRP)/acetylacetone (ACAC) as an initiation system. The structural analysis results demonstrated that the grafting of AA and MA onto starch was successful. Furthermore, the impact of the grafting reaction conditions on the grafting effect and the characteristics of the resulting grafted products were also examined. The results demonstrated that AA and MA were successfully grafted onto starch. The optimal conditions for starch grafting with AA/MA were identified as a reaction time of 4 h, an HRP enzyme concentration of 12 U/mL, a total monomer/starch ratio of 4:6, and a molar ratio of AA/MA feeding of 3:7. The viscosity and viscoelasticity of the modified starch slurry increased, and the film-forming property was enhanced. Compared with the original starch film, the modified film markedly increased the flexibility and tensile strength. Furthermore, an increased acrylic acid content maintained the original hydrophilicity of the modified starch film. The horseradish peroxidase (HRP)/acetone peroxide (ACAC) binary system serves as an initiator to stimulate the generation of free radicals from starch, acrylic acid (AA), and methyl acrylate (MA). Simultaneously, while AA and MA undergo self-polymerization and copolymerization, they also get grafted onto starch chains through self-polymerization and alternating copolymerization. A substantial number of branched small-molecule chains are uniformly grafted onto the primary chain of starch with a low molecular weight.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 2","pages":"189-201"},"PeriodicalIF":2.3,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1038/s41428-024-00987-6
Takuto Sato, Naoki Chikuba, Daichi Ida, Masashi Osa
To quantitatively evaluate the solvent quality of d-limonene for polystyrene, light-scattering experiments were performed on polystyrene in d-limonene. Molecular-level information on the intermolecular interactions between the repeat unit of polystyrene and d-limonene was obtained by means of computational simulations. From the light-scattering experiments, the mean-square radius of gyration 〈S2〉 values for atactic polystyrene (a-PS) with weight-average molecular weights ranging from 3.73 × 104 to 2.87 × 106 in d-limonene at 25.0 °C were determined to be between those in toluene, a good solvent, and those in cyclohexane, a poor solvent. Moreover, the second virial coefficient A2 values of a-PS in d-limonene were smaller than half of those in toluene. The 〈S2〉 and A2 values were analyzed according to the helical wormlike chain model, and the binary-cluster integral β, representing the magnitude of the excluded volume between constituent segments of a-PS, was found to exhibit an intermediate value between those in toluene and cyclohexane, confirming that d-limonene is a medium solvent for a-PS. The intermolecular interaction energy between cumene as a model compound representing the repeat unit of polystyrene and d-limonene, which was obtained from the computational simulations, supported the estimated solvent quality for polystyrene. The intermolecular interactions between polystyrene (PS) and d-limonene were comprehensively studied utilizing both light-scattering experiments and computational simulations. From analyses of the mean-square radius of gyration 〈S2〉 and second virial coefficient A2 for PS in d-limonene determined by the light-scattering experiments, d-limonene was confirmed as a medium solvent with intermediate solvent quality between good solvents like toluene and poor solvents like cyclohexane for PS. The intermolecular interaction energy between repeat unit of PS and d-limonene, which was obtained from the computational simulations, supported the estimated solvent quality for PS.
{"title":"A combined study on intermolecular interactions between polystyrene and d-limonene utilizing light-scattering experiments and computational simulations","authors":"Takuto Sato, Naoki Chikuba, Daichi Ida, Masashi Osa","doi":"10.1038/s41428-024-00987-6","DOIUrl":"10.1038/s41428-024-00987-6","url":null,"abstract":"To quantitatively evaluate the solvent quality of d-limonene for polystyrene, light-scattering experiments were performed on polystyrene in d-limonene. Molecular-level information on the intermolecular interactions between the repeat unit of polystyrene and d-limonene was obtained by means of computational simulations. From the light-scattering experiments, the mean-square radius of gyration 〈S2〉 values for atactic polystyrene (a-PS) with weight-average molecular weights ranging from 3.73 × 104 to 2.87 × 106 in d-limonene at 25.0 °C were determined to be between those in toluene, a good solvent, and those in cyclohexane, a poor solvent. Moreover, the second virial coefficient A2 values of a-PS in d-limonene were smaller than half of those in toluene. The 〈S2〉 and A2 values were analyzed according to the helical wormlike chain model, and the binary-cluster integral β, representing the magnitude of the excluded volume between constituent segments of a-PS, was found to exhibit an intermediate value between those in toluene and cyclohexane, confirming that d-limonene is a medium solvent for a-PS. The intermolecular interaction energy between cumene as a model compound representing the repeat unit of polystyrene and d-limonene, which was obtained from the computational simulations, supported the estimated solvent quality for polystyrene. The intermolecular interactions between polystyrene (PS) and d-limonene were comprehensively studied utilizing both light-scattering experiments and computational simulations. From analyses of the mean-square radius of gyration 〈S2〉 and second virial coefficient A2 for PS in d-limonene determined by the light-scattering experiments, d-limonene was confirmed as a medium solvent with intermediate solvent quality between good solvents like toluene and poor solvents like cyclohexane for PS. The intermolecular interaction energy between repeat unit of PS and d-limonene, which was obtained from the computational simulations, supported the estimated solvent quality for PS.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 2","pages":"171-179"},"PeriodicalIF":2.3,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-11DOI: 10.1038/s41428-024-00981-y
Shin-nosuke Nishimura, Yuta Kashihara, Tomoyuki Koga
The glass transition temperature under dry conditions (Tg,dry) is an important factor for understanding the properties of polymeric materials; however, Tg,dry is often not a suitable factor for understanding the functions of biomaterials because these materials are used in water or are in contact with water. Therefore, the glass transition temperature under hydrated conditions (Tg,wet) is a crucial thermal property of polymers, particularly biomaterials. Traditional Tg,wet measurements require significant skill and are prone to error. To address this, we developed a machine learning (ML) model to predict Tg,wet from the polymer structures using a small dataset of 33 polymers. SMILES was used to generate Morgan fingerprints (MFPs) and SMILES-fragments (FLs), which serve as descriptors for the ML models. We used both random forest (RF) and ridge regression (RR) algorithms, and these algorithms were optimizing through grid search and cross-validation. The ML models using only chemical structure descriptors (MFP and FL) exhibited poor predictive performance and showed overfitting. However, when the values of Tg,dry were included as an explanatory variable, the RR model using MFP provided the best performance. These results highlight the importance of incorporating the data of Tg,dry to enhance the prediction of Tg,wet. Our model has the potential to facilitate the design of functional biomaterials. The glass transition temperature of the dry polymers (Tg,dry) is a useful parameter for predicting that of hydrated polymers (Tg,wet). By combining Tg,dry and chemical structures, simple machine learning models for Tg,wet can be constructed even with a small dataset.
{"title":"Simple machine learning model for the glass transition temperatures of hydrated polymers","authors":"Shin-nosuke Nishimura, Yuta Kashihara, Tomoyuki Koga","doi":"10.1038/s41428-024-00981-y","DOIUrl":"10.1038/s41428-024-00981-y","url":null,"abstract":"The glass transition temperature under dry conditions (Tg,dry) is an important factor for understanding the properties of polymeric materials; however, Tg,dry is often not a suitable factor for understanding the functions of biomaterials because these materials are used in water or are in contact with water. Therefore, the glass transition temperature under hydrated conditions (Tg,wet) is a crucial thermal property of polymers, particularly biomaterials. Traditional Tg,wet measurements require significant skill and are prone to error. To address this, we developed a machine learning (ML) model to predict Tg,wet from the polymer structures using a small dataset of 33 polymers. SMILES was used to generate Morgan fingerprints (MFPs) and SMILES-fragments (FLs), which serve as descriptors for the ML models. We used both random forest (RF) and ridge regression (RR) algorithms, and these algorithms were optimizing through grid search and cross-validation. The ML models using only chemical structure descriptors (MFP and FL) exhibited poor predictive performance and showed overfitting. However, when the values of Tg,dry were included as an explanatory variable, the RR model using MFP provided the best performance. These results highlight the importance of incorporating the data of Tg,dry to enhance the prediction of Tg,wet. Our model has the potential to facilitate the design of functional biomaterials. The glass transition temperature of the dry polymers (Tg,dry) is a useful parameter for predicting that of hydrated polymers (Tg,wet). By combining Tg,dry and chemical structures, simple machine learning models for Tg,wet can be constructed even with a small dataset.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 2","pages":"225-231"},"PeriodicalIF":2.3,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1038/s41428-024-00975-w
Yoshiyuki Kamo, Akikazu Matsumoto
While epoxy resins exhibit excellent mechanical and insulating properties as well as excellent stability against heat and chemicals, epoxy adhesives also have drawbacks such as brittleness and stress concentration. Rubber-based materials are often added to epoxy adhesives to increase toughness, but they are sensitive to heat and moisture, limiting their effectiveness in harsh environments. In this study, we propose a new sheet-type adhesive consisting of a conventional liquid epoxy adhesive and an epoxy monolith sheet with internal continuous pores, using the advantageous properties of the flexibility and toughness of the epoxy monolith to avoid stress concentration. We evaluated the adhesion strength for metal bonding using the sheet-type epoxy adhesives via a lap-shear tensile adhesion test at various temperatures. The total destruction energy was also estimated via a tapered double cantilever beam test. Furthermore, a heat cycle adhesion test was conducted using two types of metallic materials with different coefficients of thermal expansion to elucidate the effect of the monolith sheet on the improvement of interfacial failure induced by stress concentration. We propose a new sheet-type adhesive consisting of a conventional liquid epoxy adhesive and an epoxy monolith sheet with internal continuous pores to avoid stress concentration. We evaluated the adhesion strength for metal bonding using sheet-type epoxy adhesives via lap-shear tensile adhesion tests at various temperatures. The tapered double cantilever beam test revealed that the combination of the epoxy adhesive and the monolith sheet effectively increased the total fracture energy. Furthermore, a heat cycle adhesion test was conducted using two types of metallic materials with different coefficients of thermal expansion to elucidate the effect of the monolith sheet on the improvement of interfacial failure induced by stress concentration.
{"title":"Stress relaxation and improved fracture toughness of metal bonding using flexible monolith sheets and an epoxy adhesive","authors":"Yoshiyuki Kamo, Akikazu Matsumoto","doi":"10.1038/s41428-024-00975-w","DOIUrl":"10.1038/s41428-024-00975-w","url":null,"abstract":"While epoxy resins exhibit excellent mechanical and insulating properties as well as excellent stability against heat and chemicals, epoxy adhesives also have drawbacks such as brittleness and stress concentration. Rubber-based materials are often added to epoxy adhesives to increase toughness, but they are sensitive to heat and moisture, limiting their effectiveness in harsh environments. In this study, we propose a new sheet-type adhesive consisting of a conventional liquid epoxy adhesive and an epoxy monolith sheet with internal continuous pores, using the advantageous properties of the flexibility and toughness of the epoxy monolith to avoid stress concentration. We evaluated the adhesion strength for metal bonding using the sheet-type epoxy adhesives via a lap-shear tensile adhesion test at various temperatures. The total destruction energy was also estimated via a tapered double cantilever beam test. Furthermore, a heat cycle adhesion test was conducted using two types of metallic materials with different coefficients of thermal expansion to elucidate the effect of the monolith sheet on the improvement of interfacial failure induced by stress concentration. We propose a new sheet-type adhesive consisting of a conventional liquid epoxy adhesive and an epoxy monolith sheet with internal continuous pores to avoid stress concentration. We evaluated the adhesion strength for metal bonding using sheet-type epoxy adhesives via lap-shear tensile adhesion tests at various temperatures. The tapered double cantilever beam test revealed that the combination of the epoxy adhesive and the monolith sheet effectively increased the total fracture energy. Furthermore, a heat cycle adhesion test was conducted using two types of metallic materials with different coefficients of thermal expansion to elucidate the effect of the monolith sheet on the improvement of interfacial failure induced by stress concentration.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 2","pages":"203-214"},"PeriodicalIF":2.3,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-00975-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The selective deprotection of tertiary-butyl (tert-Bu) esters in diblock copolymers of polyesters was studied via heterogeneous acid catalysts and flow reactors. Diblock copolymers composed of n-butyl methacrylate (nBMA) as the 1st block and tert-butyl methacrylate (tBMA) as the 2nd block were prepared by group transfer polymerization (GTP) using diisobutyl ketone (DIBK) as the solvent. The selective deprotection of the tert-Bu ester in the poly(nBMA-b-tBMA) under flow conditions was examined. The results show that the selective deprotection of the tert-Bu ester was achieved successfully via an acidic macroreticular polymeric catalyst, Amberlyst 35DRY, packed in a flow reactor. The deprotection process required 15 min of residence at 180 °C to yield acidic poly(nBMA-b-methacrylic acid) with a polydispersity index (Ð) value as low as 1.28. The durability of the catalyst was also examined during a continuous process for 1500 min by an HPLC pump. Selective deprotection of tertiary-butyl (tert-Bu) ester in poly(n-butyl methacrylate-b-tert-butyl methacrylate) was studied via heterogeneous acid catalysts and flow reactors. We found that selective deprotection of tert-Bu ester was achieved successfully using an acidic macroreticular polymeric catalyst, Amberlyst 35DRY, packed in a flow reactor. The deprotection process required 15 min of residence time at 180 °C to give an acidic poly(n-butyl methacrylate-b-methacrylic acid) with a small polydispersity index (Ð) value such as 1.28.
{"title":"Deprotection of the tert-butyl ester of poly(n-butyl methacrylate-b-tert-butyl methacrylate) under flow conditions by heterogeneous catalysts leading to acidic diblock copolymers","authors":"Ryo Takabayashi, Stephan Feser, Hiroshi Yonehara, Mamoru Hyodo, Ilhyong Ryu, Takahide Fukuyama","doi":"10.1038/s41428-024-00978-7","DOIUrl":"10.1038/s41428-024-00978-7","url":null,"abstract":"The selective deprotection of tertiary-butyl (tert-Bu) esters in diblock copolymers of polyesters was studied via heterogeneous acid catalysts and flow reactors. Diblock copolymers composed of n-butyl methacrylate (nBMA) as the 1st block and tert-butyl methacrylate (tBMA) as the 2nd block were prepared by group transfer polymerization (GTP) using diisobutyl ketone (DIBK) as the solvent. The selective deprotection of the tert-Bu ester in the poly(nBMA-b-tBMA) under flow conditions was examined. The results show that the selective deprotection of the tert-Bu ester was achieved successfully via an acidic macroreticular polymeric catalyst, Amberlyst 35DRY, packed in a flow reactor. The deprotection process required 15 min of residence at 180 °C to yield acidic poly(nBMA-b-methacrylic acid) with a polydispersity index (Ð) value as low as 1.28. The durability of the catalyst was also examined during a continuous process for 1500 min by an HPLC pump. Selective deprotection of tertiary-butyl (tert-Bu) ester in poly(n-butyl methacrylate-b-tert-butyl methacrylate) was studied via heterogeneous acid catalysts and flow reactors. We found that selective deprotection of tert-Bu ester was achieved successfully using an acidic macroreticular polymeric catalyst, Amberlyst 35DRY, packed in a flow reactor. The deprotection process required 15 min of residence time at 180 °C to give an acidic poly(n-butyl methacrylate-b-methacrylic acid) with a small polydispersity index (Ð) value such as 1.28.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 2","pages":"215-224"},"PeriodicalIF":2.3,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-17DOI: 10.1038/s41428-024-00968-9
Kota Hashimoto, Natsuki Inaba, Keitaro Matsuoka, Kazuki Sada
Dual stimuli-responsiveness in non-aqueous media could allow various molecular designs using a system that is not compatible with aqueous media. However, the difficulty in controlling the desolvation of the polymer chains in non-aqueous media for lower critical solution temperature (LCST)-type phase separation at ambient temperature has hindered the attainment of dual stimuli-responsiveness based on chemical stimuli. In this study, we rationally designed dual chemo- and thermo-responsive phase separations of poly(4-hydroxystyrene) in non-aqueous media. The LCST-type thermo-responsiveness of poly(4-hydroxystyrene) in 1,4-dioxane/toluene was considerably altered by the addition of small amounts of hydrogen-bonding molecules as chemical stimuli. Secondary amines or molecules containing two hydrogen-bonding functional groups formed stronger hydrogen bonds with the polymer chains than 1,4-dioxane, which altered the solvation state and induced the UCST-type thermo-responsiveness or insolubility of PHS. This dual stimuli-responsive system could serve as a chemical sensor to detect the presence of acids. Dual chemo- and thermo-responsive phase separations of poly(4-hydroxystyrene) in non-aqueous media were demonstrated. The addition of small amounts of hydrogen-bonding molecules as chemical stimuli caused a considerable change of LCST-type thermo-responsiveness of poly(4-hydroxystyrene) in 1,4-dioxane/toluene. Secondary amines or molecules containing two hydrogen-bonding functional groups could cross-link the polymer chains through the hydrogen bonds, which altered the solvation state and induced the UCST-type thermo-responsiveness or insolubility of the polymer. This dual stimuli-responsive system worked as a chemical sensor to detect the presence of acids.
{"title":"Rational design of dual Chemo- and Thermo-responsive phase separation of Poly(4-hydroxystyrene) in non-aqueous media","authors":"Kota Hashimoto, Natsuki Inaba, Keitaro Matsuoka, Kazuki Sada","doi":"10.1038/s41428-024-00968-9","DOIUrl":"10.1038/s41428-024-00968-9","url":null,"abstract":"Dual stimuli-responsiveness in non-aqueous media could allow various molecular designs using a system that is not compatible with aqueous media. However, the difficulty in controlling the desolvation of the polymer chains in non-aqueous media for lower critical solution temperature (LCST)-type phase separation at ambient temperature has hindered the attainment of dual stimuli-responsiveness based on chemical stimuli. In this study, we rationally designed dual chemo- and thermo-responsive phase separations of poly(4-hydroxystyrene) in non-aqueous media. The LCST-type thermo-responsiveness of poly(4-hydroxystyrene) in 1,4-dioxane/toluene was considerably altered by the addition of small amounts of hydrogen-bonding molecules as chemical stimuli. Secondary amines or molecules containing two hydrogen-bonding functional groups formed stronger hydrogen bonds with the polymer chains than 1,4-dioxane, which altered the solvation state and induced the UCST-type thermo-responsiveness or insolubility of PHS. This dual stimuli-responsive system could serve as a chemical sensor to detect the presence of acids. Dual chemo- and thermo-responsive phase separations of poly(4-hydroxystyrene) in non-aqueous media were demonstrated. The addition of small amounts of hydrogen-bonding molecules as chemical stimuli caused a considerable change of LCST-type thermo-responsiveness of poly(4-hydroxystyrene) in 1,4-dioxane/toluene. Secondary amines or molecules containing two hydrogen-bonding functional groups could cross-link the polymer chains through the hydrogen bonds, which altered the solvation state and induced the UCST-type thermo-responsiveness or insolubility of the polymer. This dual stimuli-responsive system worked as a chemical sensor to detect the presence of acids.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 2","pages":"181-188"},"PeriodicalIF":2.3,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The stress relaxation test is an effective and facile method for clarifying the nonlinear rheological behavior of soft materials. A thorough analysis of the stress relaxation behavior offers valuable insights into the molecular dynamics. However, the stress relaxation behavior and underlying molecular dynamics of polymer/particle mixtures remain poorly understood, despite their widespread industrial application. In this study, we systematically investigated the nonlinear stress relaxation behavior of a simple-structured poly(ethylene oxide) (PEO)/silica nanoparticle aqueous mixture. Time‒strain separability was observed at high polymer concentrations, with the stress relaxation attributable to the relaxation of the polymer matrix. At lower polymer concentrations, the time‒strain separability was no longer valid, and changes in absorbance over time suggested that stress relaxation originated from the relaxation of the aggregated structures. A transition from time‒strain separability to inseparability was observed when the estimated number of PEO molecules forming interparticle bridges was less than 1; this suggests that structural changes during shear loading occur only when new interparticle polymer bridges are formed, leading to the development of clustered structures. These results provide a basic understanding of the relationship between deformation and relaxation, which is crucial for systematically understanding the nonlinear rheology of polymeric materials. Normalized relaxation time as a function of the estimated number of interparticle polymer bridges (nbridge). Images show the molecular dynamics pertaining to nbridge < 1 and 1 < nbridge.
{"title":"Nonlinear stress relaxation and failure of time‒strain separability of aqueous poly(ethylene oxide)/silica nanoparticle mixtures","authors":"Saki Kusakabe, Takuya Katashima, Ichiro Sakuma, Yuki Akagi","doi":"10.1038/s41428-024-00974-x","DOIUrl":"10.1038/s41428-024-00974-x","url":null,"abstract":"The stress relaxation test is an effective and facile method for clarifying the nonlinear rheological behavior of soft materials. A thorough analysis of the stress relaxation behavior offers valuable insights into the molecular dynamics. However, the stress relaxation behavior and underlying molecular dynamics of polymer/particle mixtures remain poorly understood, despite their widespread industrial application. In this study, we systematically investigated the nonlinear stress relaxation behavior of a simple-structured poly(ethylene oxide) (PEO)/silica nanoparticle aqueous mixture. Time‒strain separability was observed at high polymer concentrations, with the stress relaxation attributable to the relaxation of the polymer matrix. At lower polymer concentrations, the time‒strain separability was no longer valid, and changes in absorbance over time suggested that stress relaxation originated from the relaxation of the aggregated structures. A transition from time‒strain separability to inseparability was observed when the estimated number of PEO molecules forming interparticle bridges was less than 1; this suggests that structural changes during shear loading occur only when new interparticle polymer bridges are formed, leading to the development of clustered structures. These results provide a basic understanding of the relationship between deformation and relaxation, which is crucial for systematically understanding the nonlinear rheology of polymeric materials. Normalized relaxation time as a function of the estimated number of interparticle polymer bridges (nbridge). Images show the molecular dynamics pertaining to nbridge < 1 and 1 < nbridge.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 2","pages":"163-170"},"PeriodicalIF":2.3,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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