A photoresponsive Fe3+-cross-linked poly(acrylic acid) hydrogel showing tunable healing, photopatterning, and light sensing is reported. The hydrogel is fabricated by simply mixing acrylic acid, Ag+, ammonium persulfate, Fe3+, and citric acid in water at room temperature. A gelation kinetics investigation demonstrates a short network occurrence time of 86 ± 3.5 s. The citric acid in the hydrogel inhibits covalent cross-linking and enables the photocleavage of Fe3+-COOH cross-linking by reducing Fe3+ to Fe2+, resulting in a solid-to-liquid transition. When the oxidizer H2O2 or O2 is imposed on the photoliquefied hydrogel, the Fe3+-COOH cross-linking is restored and the liquid-to-solid transition can be achieved. The photoresponsive hydrogel is demonstrated to be self-healable due to the dynamic nature of Fe3+-COOH cross-linking. It also shows fast light/H2O2-assisted healing through time-controlled photoliquefaction. The hydrogel sheet is also used to print portraits of people and a photo of a dog by photopatterning. We finally demonstrate that the hydrogel shows reversible electric resistance change in response to photoirradiation. We expect that the COOH-containing monomer/APS/CA/metal ion gelation chemistry can not only serve as a general strategy to readily and rapidly produce healable hydrogels, but also enrich the toolbox of manufacturing photopatterning materials and light sensors.
{"title":"One-Pot and Fast Synthesis of Hydrogels with Photoswitchable Dynamic Coordination Cross-Linking for Tunable Healing, Photopatterning, and Light Sensing","authors":"Xinyuan Wan, Kai Gou, Yongqi Liu, Jingzhi Tang, Qiuli Tan, Gengsheng Weng","doi":"10.1021/acs.macromol.5c00198","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00198","url":null,"abstract":"A photoresponsive Fe<sup>3+</sup>-cross-linked poly(acrylic acid) hydrogel showing tunable healing, photopatterning, and light sensing is reported. The hydrogel is fabricated by simply mixing acrylic acid, Ag<sup>+</sup>, ammonium persulfate, Fe<sup>3+</sup>, and citric acid in water at room temperature. A gelation kinetics investigation demonstrates a short network occurrence time of 86 ± 3.5 s. The citric acid in the hydrogel inhibits covalent cross-linking and enables the photocleavage of Fe<sup>3+</sup>-COOH cross-linking by reducing Fe<sup>3+</sup> to Fe<sup>2+</sup>, resulting in a solid-to-liquid transition. When the oxidizer H<sub>2</sub>O<sub>2</sub> or O<sub>2</sub> is imposed on the photoliquefied hydrogel, the Fe<sup>3+</sup>-COOH cross-linking is restored and the liquid-to-solid transition can be achieved. The photoresponsive hydrogel is demonstrated to be self-healable due to the dynamic nature of Fe<sup>3+</sup>-COOH cross-linking. It also shows fast light/H<sub>2</sub>O<sub>2</sub>-assisted healing through time-controlled photoliquefaction. The hydrogel sheet is also used to print portraits of people and a photo of a dog by photopatterning. We finally demonstrate that the hydrogel shows reversible electric resistance change in response to photoirradiation. We expect that the COOH-containing monomer/APS/CA/metal ion gelation chemistry can not only serve as a general strategy to readily and rapidly produce healable hydrogels, but also enrich the toolbox of manufacturing photopatterning materials and light sensors.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"121 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-22DOI: 10.1021/acs.macromol.5c00136
Xin Zheng, Zhixin Liu, Luyao Yang, Kang Li, Lei Zhang, Yuxing Song, Yongjin Li
Polypropylene (PP) is widely used due to its excellent properties, but its linear structure and corresponding low melt strength greatly limit its application. We herein investigate the preparation of long chain branched polypropylene (LCB-PP) via reactive processing with the employment of a novel monomer, 4-vinylguaiacol (4-VG). The results show that the introduction of 4-VG effectively hinders the degradation of PP during the reactive processing and promotes the formation of long chain branched structures, which was confirmed by high-temperature gel permeation chromatography. The branching degree of prepared LCB-PPs could be easily controlled by adjusting the molar ratio of 4-VG to the dicumyl peroxide (DCP) initiator. It has been demonstrated by the Mark–Houwink plots that LCB-PP2 exhibits the highest branching degree when the molar ratio of 4-VG to DCP is approximately 2:1. Besides, LCB-PPs with a higher branching degree also possess a higher melt strength and higher expansion ratio after being foamed. Notably, LCB-PP2 shows remarkably high melt strength and expansion ratio of up to 1.7 × 104 Pa s and 30.7, which are 10 and 28 times those of PP, respectively. Also, pronounced tensile strain hardening behavior is observed for these LCB-PPs. It is believed that the unique combination of conjugated double bonds and the phenolic hydroxyl group in 4-VG plays an important role in hindering degradation and introducing long branches during the reactive processing of PP. This work provides a new perspective for the preparation of high-performance and functionalized PP materials.
{"title":"Facile Formation of Long Chain Branched Polypropylene via Reactive Processing","authors":"Xin Zheng, Zhixin Liu, Luyao Yang, Kang Li, Lei Zhang, Yuxing Song, Yongjin Li","doi":"10.1021/acs.macromol.5c00136","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00136","url":null,"abstract":"Polypropylene (PP) is widely used due to its excellent properties, but its linear structure and corresponding low melt strength greatly limit its application. We herein investigate the preparation of long chain branched polypropylene (LCB-PP) via reactive processing with the employment of a novel monomer, 4-vinylguaiacol (4-VG). The results show that the introduction of 4-VG effectively hinders the degradation of PP during the reactive processing and promotes the formation of long chain branched structures, which was confirmed by high-temperature gel permeation chromatography. The branching degree of prepared LCB-PPs could be easily controlled by adjusting the molar ratio of 4-VG to the dicumyl peroxide (DCP) initiator. It has been demonstrated by the Mark–Houwink plots that LCB-PP<sub>2</sub> exhibits the highest branching degree when the molar ratio of 4-VG to DCP is approximately 2:1. Besides, LCB-PPs with a higher branching degree also possess a higher melt strength and higher expansion ratio after being foamed. Notably, LCB-PP<sub>2</sub> shows remarkably high melt strength and expansion ratio of up to 1.7 × 10<sup>4</sup> Pa s and 30.7, which are 10 and 28 times those of PP, respectively. Also, pronounced tensile strain hardening behavior is observed for these LCB-PPs. It is believed that the unique combination of conjugated double bonds and the phenolic hydroxyl group in 4-VG plays an important role in hindering degradation and introducing long branches during the reactive processing of PP. This work provides a new perspective for the preparation of high-performance and functionalized PP materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"219 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-21DOI: 10.1021/acs.macromol.5c00501
Yiwen Zheng, Vikas Varshney, Aniruddh Vashisth
Vitrimers are a novel class of sustainable polymers with dynamic covalent adaptive networks driven by bond-exchange reactions between different constituents, making vitrimers reprocessable and recyclable. Current modeling approaches of bond-exchange reactions fall short in realistically capturing the complete reaction pathways, which limits our understanding of the viscoelastic properties of vitrimers. This research addresses these limitations by extending and employing the Accelerated reactive molecular dynamics (ReaxFF) technique, thus enabling a more accurate representation of vitrimer viscoelastic behavior at the molecular level. Bayesian optimization is employed to select force field parameters within the Accelerated ReaxFF framework, and an empirical function is proposed to model temperature dependence, thereby controlling the reaction probabilities under varying temperatures. The extended framework is employed to simulate nonisothermal creep behavior of vitrimers under different applied stress levels, heating rates, and numbers of reactions. The simulation results agree with experimental findings in the literature, validating the robustness of the framework.
{"title":"Accelerated ReaxFF Simulations of Vitrimers with Dynamic Covalent Adaptive Networks","authors":"Yiwen Zheng, Vikas Varshney, Aniruddh Vashisth","doi":"10.1021/acs.macromol.5c00501","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00501","url":null,"abstract":"Vitrimers are a novel class of sustainable polymers with dynamic covalent adaptive networks driven by bond-exchange reactions between different constituents, making vitrimers reprocessable and recyclable. Current modeling approaches of bond-exchange reactions fall short in realistically capturing the complete reaction pathways, which limits our understanding of the viscoelastic properties of vitrimers. This research addresses these limitations by extending and employing the Accelerated reactive molecular dynamics (ReaxFF) technique, thus enabling a more accurate representation of vitrimer viscoelastic behavior at the molecular level. Bayesian optimization is employed to select force field parameters within the Accelerated ReaxFF framework, and an empirical function is proposed to model temperature dependence, thereby controlling the reaction probabilities under varying temperatures. The extended framework is employed to simulate nonisothermal creep behavior of vitrimers under different applied stress levels, heating rates, and numbers of reactions. The simulation results agree with experimental findings in the literature, validating the robustness of the framework.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"268 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The remarkable ductility and enhanced toughness of metal–ligand-based hydrogels caused by physical cross-links that improve their mechanical properties have proven the efficacy of hydrogels in various engineering applications. Here, we bring the first comprehensive investigation of hydrogels under bulge testing. The multiaxial response of these materials is crucial for enhanced durability and load-bearing capability. In this study, we derive a hyperelastic constitutive model with a description of failure and validate it experimentally. The latter model is further used to analyze cavitation in these materials. This study demonstrates that incorporating imidazole–Ni2+ metal–ligand cross-links can significantly enhance several mechanical properties. For instance, increasing the imidazole content from 40 to 70 mol % improves the elastic modulus by 400% and the ultimate equibiaxial stress by 80%. The detailed experimental investigation reveals that the inflation of these hydrogels strongly depends on structural evolution. The current study paves the way for the development of novel experimental techniques and constitutive models to fine-tune the mechanical properties of hydrogels as per user requirements.
{"title":"Mechanics of Physically Cross-Linked Hydrogels: Experiments and Theoretical Modeling","authors":"Mohit Goswami, Agniva Dutta, Rishi Kulshreshtha, Gleb Vasilyev, Eyal Zussman, Konstantin Volokh","doi":"10.1021/acs.macromol.5c00486","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00486","url":null,"abstract":"The remarkable ductility and enhanced toughness of metal–ligand-based hydrogels caused by physical cross-links that improve their mechanical properties have proven the efficacy of hydrogels in various engineering applications. Here, we bring the first comprehensive investigation of hydrogels under bulge testing. The multiaxial response of these materials is crucial for enhanced durability and load-bearing capability. In this study, we derive a hyperelastic constitutive model with a description of failure and validate it experimentally. The latter model is further used to analyze cavitation in these materials. This study demonstrates that incorporating imidazole–Ni<sup>2+</sup> metal–ligand cross-links can significantly enhance several mechanical properties. For instance, increasing the imidazole content from 40 to 70 mol % improves the elastic modulus by 400% and the ultimate equibiaxial stress by 80%. The detailed experimental investigation reveals that the inflation of these hydrogels strongly depends on structural evolution. The current study paves the way for the development of novel experimental techniques and constitutive models to fine-tune the mechanical properties of hydrogels as per user requirements.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"8 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-21DOI: 10.1021/acs.macromol.5c00318
Zhehao Hu, Tianyi Wang, Jiaping Lin, Liquan Wang
Copolymerization, producing varying copolymer sequences, is a practical method to control the glass transition temperature, which can broaden the temperature range of their use and adapt to different scenarios. However, the connection of copolymer sequences with glass transition temperatures is still unclear. In this work, we employed an all-atom molecular dynamics simulation to explore the sequence effect on the glass transition temperature of silicone-containing copolymers. The results indicated that the Flory–Fox equation and linear relation effectively describe the correlation between glass transition temperatures and compositions of poly(methylphenyl-co-methylvinyl) siloxane with alternating block sequences, while diblock sequences exhibit positive deviations. In comparison, the glass transition temperatures of poly(methylphenyl-co-dimethyl) siloxane with all sequences deviate positively from the Flory–Fox equation and linear relation. The analysis revealed that the self-concentration effect plays a dominant role in the positive deviations, which is closely associated with the rigidity of the monomers constituting the copolymers. The result provides a fundamental understanding of the sequence effect on the glass transition temperature of copolymers and could guide the rational design of silicone-containing copolymers with controlled glass transition temperatures.
{"title":"Sequence Effects on the Glass Transition Temperature of Silicone-Containing Copolymers","authors":"Zhehao Hu, Tianyi Wang, Jiaping Lin, Liquan Wang","doi":"10.1021/acs.macromol.5c00318","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00318","url":null,"abstract":"Copolymerization, producing varying copolymer sequences, is a practical method to control the glass transition temperature, which can broaden the temperature range of their use and adapt to different scenarios. However, the connection of copolymer sequences with glass transition temperatures is still unclear. In this work, we employed an all-atom molecular dynamics simulation to explore the sequence effect on the glass transition temperature of silicone-containing copolymers. The results indicated that the Flory–Fox equation and linear relation effectively describe the correlation between glass transition temperatures and compositions of poly(methylphenyl-<i>co</i>-methylvinyl) siloxane with alternating block sequences, while diblock sequences exhibit positive deviations. In comparison, the glass transition temperatures of poly(methylphenyl-<i>co</i>-dimethyl) siloxane with all sequences deviate positively from the Flory–Fox equation and linear relation. The analysis revealed that the self-concentration effect plays a dominant role in the positive deviations, which is closely associated with the rigidity of the monomers constituting the copolymers. The result provides a fundamental understanding of the sequence effect on the glass transition temperature of copolymers and could guide the rational design of silicone-containing copolymers with controlled glass transition temperatures.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"24 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-19DOI: 10.1021/acs.macromol.5c00535
Yuto Eguchi, Sadahito Aoshima, Arihiro Kanazawa
In this study, we investigated the cationic terpolymerization of styrene derivatives, oxiranes, and aromatic aldehydes to achieve precise sequence control. Cationic terpolymerization of p-methoxystyrene (pMOS), 1,2-epoxy-4-vinylcyclohexane (VCHO), and benzaldehyde (BzA) proceeded via crossover reactions, yielding terpolymers with high molecular weights (MWs). In addition, selective crossover reactions consisting of pMOS → VCHO, VCHO → BzA, and BzA → pMOS proceeded, resulting in terpolymers with controlled [(pMOS)x–(VCHO)y–BzA]n sequences. The BzA-derived propagating end, which has a structure similar to that of the styrene-derived propagating end, was important for effective terpolymerization as judged by inefficient crossover reactions using methyl ethyl ketone instead of benzaldehyde. By optimizing polymerization conditions, homopropagation reactions of styrene derivatives and oxiranes were almost suppressed in the terpolymerization of 4-tert-butoxystyrene, VCHO, and 2,4-dimethoxybenzaldehyde, resulting in terpolymers with ABC-type periodic sequences. The terpolymers were degraded into low-MW products by acid or oxidant via the cleavage of the crossover reaction-derived, secondary benzylic ether moieties in the main chain.
{"title":"Sequence-Controlled Cationic Terpolymerization of Styrene Derivatives, Oxiranes, and Aromatic Aldehydes: Synthesis of Acidically or Oxidatively Degradable Terpolymers","authors":"Yuto Eguchi, Sadahito Aoshima, Arihiro Kanazawa","doi":"10.1021/acs.macromol.5c00535","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00535","url":null,"abstract":"In this study, we investigated the cationic terpolymerization of styrene derivatives, oxiranes, and aromatic aldehydes to achieve precise sequence control. Cationic terpolymerization of <i>p</i>-methoxystyrene (pMOS), 1,2-epoxy-4-vinylcyclohexane (VCHO), and benzaldehyde (BzA) proceeded via crossover reactions, yielding terpolymers with high molecular weights (MWs). In addition, selective crossover reactions consisting of pMOS → VCHO, VCHO → BzA, and BzA → pMOS proceeded, resulting in terpolymers with controlled [(pMOS)<sub><i>x</i></sub>–(VCHO)<sub><i>y</i></sub>–BzA]<sub><i>n</i></sub> sequences. The BzA-derived propagating end, which has a structure similar to that of the styrene-derived propagating end, was important for effective terpolymerization as judged by inefficient crossover reactions using methyl ethyl ketone instead of benzaldehyde. By optimizing polymerization conditions, homopropagation reactions of styrene derivatives and oxiranes were almost suppressed in the terpolymerization of 4-<i>tert</i>-butoxystyrene, VCHO, and 2,4-dimethoxybenzaldehyde, resulting in terpolymers with ABC-type periodic sequences. The terpolymers were degraded into low-MW products by acid or oxidant via the cleavage of the crossover reaction-derived, secondary benzylic ether moieties in the main chain.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"28 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143849895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-19DOI: 10.1021/acs.macromol.5c00573
Ke Wang, Xiaofang Liu, Ziyan Li, Fan Zhao, Guiyan Liu, Yongfei Zeng
A new family of multistimuli-responsive acrylamide-based homopolymers with different end pendant substituents were prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization. They include three types of multistimuli-response: temperature/pH/CO2-response, temperature/pH/redox-response, and temperature/pH/light-response. When the terminal substituent was ethyl and tetrahydropyran, P(Et-N-AM) and P(THP-N-AM) exhibited lower critical solution temperature (LCST) behavior in water, which can be adjusted by degree of polymerization (DP) and concentration of polymer, additives, pH, and the injection of CO2/N2 to the solution. When the terminal substituents were phenyl, ferrocene, and azobenzene, P(Ph-N-AM), P(Fc-N-AM), and P(Azo-N-AM) were insoluble in water due to the increase of hydrophobicity, but the upper critical solution temperature (UCST) was exhibited in the mixed solution of nBuOH/water and can be adjusted by the addition of acid or base. P(Fc-N-AM) was also redox-responsive, and its UV/vis absorption peaks changed with the addition of FeCl3/VC. P(Azo-N-AM) was also light-responsive, and under UV/blue light radiation, the characteristic peaks of its UV/vis absorption spectrum changed reversibly. In addition, the three homopolymers were amphiphilic, which can self-assemble in solution, and the obtained micelles were also responsive. Finally, nile red (NR) was used as a hydrophobic drug model, and the controlled release behavior of NR-loaded micelles of P(Fc-N-AM) and P(Azo-N-AM) under different stimuli was investigated. This work has greatly enriched the family of multistimuli-responsive poly(N-substituted acrylamide)s, and the synthetic steps of homopolymers were simple; the responsive behavior was sensitive, and the species were rich. It provides a reference for the design of novel stimuli-responsive polymers and has a good application prospect in self-assembly, drug release, and other fields.
{"title":"New Family of Multistimuli-Responsive Acrylamide-Based Homopolymers: Synthesis, Responsive Behavior, and Application in Controlled Release","authors":"Ke Wang, Xiaofang Liu, Ziyan Li, Fan Zhao, Guiyan Liu, Yongfei Zeng","doi":"10.1021/acs.macromol.5c00573","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00573","url":null,"abstract":"A new family of multistimuli-responsive acrylamide-based homopolymers with different end pendant substituents were prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization. They include three types of multistimuli-response: temperature/pH/CO<sub>2</sub>-response, temperature/pH/redox-response, and temperature/pH/light-response. When the terminal substituent was ethyl and tetrahydropyran, P(Et-N-AM) and P(THP-N-AM) exhibited lower critical solution temperature (LCST) behavior in water, which can be adjusted by degree of polymerization (DP) and concentration of polymer, additives, pH, and the injection of CO<sub>2</sub>/N<sub>2</sub> to the solution. When the terminal substituents were phenyl, ferrocene, and azobenzene, P(Ph-N-AM), P(Fc-N-AM), and P(Azo-N-AM) were insoluble in water due to the increase of hydrophobicity, but the upper critical solution temperature (UCST) was exhibited in the mixed solution of <sup><i>n</i></sup>BuOH/water and can be adjusted by the addition of acid or base. P(Fc-N-AM) was also redox-responsive, and its UV/vis absorption peaks changed with the addition of FeCl<sub>3</sub>/VC. P(Azo-N-AM) was also light-responsive, and under UV/blue light radiation, the characteristic peaks of its UV/vis absorption spectrum changed reversibly. In addition, the three homopolymers were amphiphilic, which can self-assemble in solution, and the obtained micelles were also responsive. Finally, nile red (NR) was used as a hydrophobic drug model, and the controlled release behavior of NR-loaded micelles of P(Fc-N-AM) and P(Azo-N-AM) under different stimuli was investigated. This work has greatly enriched the family of multistimuli-responsive poly(<i>N</i>-substituted acrylamide)s, and the synthetic steps of homopolymers were simple; the responsive behavior was sensitive, and the species were rich. It provides a reference for the design of novel stimuli-responsive polymers and has a good application prospect in self-assembly, drug release, and other fields.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"28 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143849898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-19DOI: 10.1021/acs.macromol.5c00344
Jiayi Huang, Artem M. Rumyantsev
Conjugated polymers comprise alternating single and double bonds along the backbones, which ensures their electrical conductivity. Herein, charge transport in them is modeled as a diffusion process, with two types of mechanisms involved: intra- and interchain hopping characterized by τ1 and τ2 times, respectively. Charge carriers’ diffusivity in isotropic melts and semidilute solutions of conjugated polymers under a weak electric field is calculated. By extending de Gennes’ approach [Phys. A: Stat. Mech. Appl.1986, 138, 206–219], we identify three universal regimes of charge transport. In the free regime, charges rapidly hop between different chains so that the charge carrier diffusivity is DF ∼ τ1–1N0. In the semifree regime, interchain hopping is slow compared to intrachain hopping, which makes diffusivity dependent on both characteristic times, DSF ∼ (τ1τ2)−1/2N0. Finally, in the captive regime, interchain hopping is strongly hindered, causing the charge carriers to traverse the entire chain before hopping to another. For flexible polymers, this leads to diffusivity increasing linearly with the chain length N, DC ∼ τ2–1N1. These laws also hold for semiflexible polymers and/or semidilute solutions, where the pairwise contact probability depends on the polymer volume fraction. Weakly and strongly fluctuating solutions are considered within the mean-field and scaling approaches, respectively. In addition to the diffusion (charge hopping) model, the conductivity of polymer systems is quantitatively described by considering them as finite resistor ladders. The charge carrier’s diffusivity and the resulting conductivity in alternating current (AC) are predicted as a function of its frequency. We believe that our findings will facilitate the rational design of polymer-based flexible and stretchable electronic devices.
{"title":"Scaling Laws for Charge Transport in Isotropic Bulks and Solutions of Conjugated Polymers","authors":"Jiayi Huang, Artem M. Rumyantsev","doi":"10.1021/acs.macromol.5c00344","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00344","url":null,"abstract":"Conjugated polymers comprise alternating single and double bonds along the backbones, which ensures their electrical conductivity. Herein, charge transport in them is modeled as a diffusion process, with two types of mechanisms involved: intra- and interchain hopping characterized by τ<sub>1</sub> and τ<sub>2</sub> times, respectively. Charge carriers’ diffusivity in isotropic melts and semidilute solutions of conjugated polymers under a weak electric field is calculated. By extending de Gennes’ approach [<i>Phys. A: Stat. Mech. Appl.</i> <b>1986</b>, <i>138</i>, 206–219], we identify three universal regimes of charge transport. In the free regime, charges rapidly hop between different chains so that the charge carrier diffusivity is <i>D</i><sub>F</sub> ∼ τ<sub>1</sub><sup>–1</sup><i>N</i><sup>0</sup>. In the semifree regime, interchain hopping is slow compared to intrachain hopping, which makes diffusivity dependent on both characteristic times, <i>D</i><sub>SF</sub> ∼ (τ<sub>1</sub>τ<sub>2</sub>)<sup>−1/2</sup><i>N</i><sup>0</sup>. Finally, in the captive regime, interchain hopping is strongly hindered, causing the charge carriers to traverse the entire chain before hopping to another. For flexible polymers, this leads to diffusivity increasing linearly with the chain length <i>N</i>, <i>D</i><sub>C</sub> ∼ τ<sub>2</sub><sup>–1</sup><i>N</i><sup>1</sup>. These laws also hold for semiflexible polymers and/or semidilute solutions, where the pairwise contact probability depends on the polymer volume fraction. Weakly and strongly fluctuating solutions are considered within the mean-field and scaling approaches, respectively. In addition to the diffusion (charge hopping) model, the conductivity of polymer systems is quantitatively described by considering them as finite resistor ladders. The charge carrier’s diffusivity and the resulting conductivity in alternating current (AC) are predicted as a function of its frequency. We believe that our findings will facilitate the rational design of polymer-based flexible and stretchable electronic devices.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"29 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143849894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-18DOI: 10.1021/acs.macromol.5c00099
Pietro Chiarantoni, Andrea Tagliabue, Massimo Mella, Cristian Micheletti
We use Langevin simulations to study the effect of ring composition on the structure and dynamics of model polycatenanes with copolyelectrolyte rings, each made of one charged and one neutral block. Key observables have a nonmonotonic dependence on ring composition, including the radius of gyration, mechanical bond length, orientational correlations, and rotational relaxation times. Microscopic analysis shows that these nonmonotonicities arise from the competition between electrostatic repulsion, pulling rings apart, and topological constraints, enforcing the proximity of neighboring rings. By locking charged-neutral interfaces at the mechanically bonded regions, this interplay can induce a strong chemical orientational order along the catenane while also hindering the local relaxation dynamics. Chemical orientation defects, manifesting as neutral–neutral interfaces, can emerge too and migrate along the catenane via coupled reorientations of neighboring rings. Our results clarify how ring composition and mechanical bonds can define the properties of topological materials across different scales.
{"title":"Effect of Ring Composition on the Statics and Dynamics of Block Copolyelectrolyte Catenanes","authors":"Pietro Chiarantoni, Andrea Tagliabue, Massimo Mella, Cristian Micheletti","doi":"10.1021/acs.macromol.5c00099","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00099","url":null,"abstract":"We use Langevin simulations to study the effect of ring composition on the structure and dynamics of model polycatenanes with copolyelectrolyte rings, each made of one charged and one neutral block. Key observables have a nonmonotonic dependence on ring composition, including the radius of gyration, mechanical bond length, orientational correlations, and rotational relaxation times. Microscopic analysis shows that these nonmonotonicities arise from the competition between electrostatic repulsion, pulling rings apart, and topological constraints, enforcing the proximity of neighboring rings. By locking charged-neutral interfaces at the mechanically bonded regions, this interplay can induce a strong chemical orientational order along the catenane while also hindering the local relaxation dynamics. Chemical orientation defects, manifesting as neutral–neutral interfaces, can emerge too and migrate along the catenane via coupled reorientations of neighboring rings. Our results clarify how ring composition and mechanical bonds can define the properties of topological materials across different scales.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"16 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polymerization-induced self-assembly (PISA) has gained widespread recognition as a potent tool for accessing nano-objects with diverse morphologies. To facilitate its practical application, further development of the self-assembly method is still urgent and challenging. We herein report an innovative self-assembly approach termed heat-induced self-assembly (HISA), enabling the preparation of nano-objects with abundant morphologies by direct thermal dissolution of solid block copolymers (BCPs) in selective solvents at elevated concentration (20% w/w). The BCPs of polyisoprene-b-polystyrene (PI-b-PS), polyisoprene-b-poly(methyl methacrylate) (PI-b-PMMA), and polyisoprene-b-poly(4-vinylpyridine) (PI-b-P4VP) were prepared by living anionic polymerization (LAP) for HISA investigation. Furthermore, this methodology was extended to heat-induced cooperative assembly (HICA) comprising PI-b-PSm/PSn (ABm/Bn) and PI-b-PSm/PI-b-PSn (ABm/ABn), where B represented the PS core-forming block. The feasibility of HISA and HICA processes was investigated, and a library of morphologies, including spheres, worms, vesicles, nanotubes, and sponges, were collected. The pseudophase diagrams were constructed for both ABm/Bn and ABm/ABn systems to provide guiding principles for the tailored morphologies. To evaluate the universality of HISA and HICA techniques, the ACm/Cn and ABm/ACn systems (C represented PMMA or P4VP core-forming block) were further investigated. The corresponding glass transition temperatures (Tgs) of BCPs in both dry and solvated states were analyzed to gain further insights into the HISA and HICA techniques. These high-concentration assembly strategies including HISA and HICA combined operational simplicity with morphological diversity, showing significant potential in practical applications.
{"title":"Expanding the Scope of Self-Assembly: Heat-Induced Self-Assembly of Block Copolymers with High Solids","authors":"Jingwei Zhang, Boyang Shi, Xiaoxiao Wu, Xiaotong Fang, Xinyue Liang, Zhou Peng, Guowei Wang","doi":"10.1021/acs.macromol.4c02808","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02808","url":null,"abstract":"Polymerization-induced self-assembly (PISA) has gained widespread recognition as a potent tool for accessing nano-objects with diverse morphologies. To facilitate its practical application, further development of the self-assembly method is still urgent and challenging. We herein report an innovative self-assembly approach termed heat-induced self-assembly (HISA), enabling the preparation of nano-objects with abundant morphologies by direct thermal dissolution of solid block copolymers (BCPs) in selective solvents at elevated concentration (20% w/w). The BCPs of polyisoprene-<i>b</i>-polystyrene (PI-<i>b</i>-PS), polyisoprene-<i>b</i>-poly(methyl methacrylate) (PI-<i>b</i>-PMMA), and polyisoprene-<i>b</i>-poly(4-vinylpyridine) (PI-<i>b</i>-P4VP) were prepared by living anionic polymerization (LAP) for HISA investigation. Furthermore, this methodology was extended to heat-induced cooperative assembly (HICA) comprising PI-<i>b</i>-PS<sub><i>m</i></sub>/PS<sub><i>n</i></sub> (AB<sub><i>m</i></sub>/B<sub><i>n</i></sub>) and PI-<i>b</i>-PS<sub><i>m</i></sub>/PI-<i>b</i>-PS<sub><i>n</i></sub> (AB<sub><i>m</i></sub>/AB<sub><i>n</i></sub>), where B represented the PS core-forming block. The feasibility of HISA and HICA processes was investigated, and a library of morphologies, including spheres, worms, vesicles, nanotubes, and sponges, were collected. The pseudophase diagrams were constructed for both AB<sub><i>m</i></sub>/B<sub><i>n</i></sub> and AB<sub><i>m</i></sub>/AB<sub><i>n</i></sub> systems to provide guiding principles for the tailored morphologies. To evaluate the universality of HISA and HICA techniques, the AC<sub><i>m</i></sub>/C<sub><i>n</i></sub> and AB<sub><i>m</i></sub>/AC<sub><i>n</i></sub> systems (C represented PMMA or P4VP core-forming block) were further investigated. The corresponding glass transition temperatures (<i>T</i><sub>g</sub>s) of BCPs in both dry and solvated states were analyzed to gain further insights into the HISA and HICA techniques. These high-concentration assembly strategies including HISA and HICA combined operational simplicity with morphological diversity, showing significant potential in practical applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"49 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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