Pub Date : 2026-02-05DOI: 10.1021/acs.macromol.5c03399
Min Wang, Jihang Yu, Yushu Tian, Jiadong Wang, Xuan Qin, Yonglai Lu
Fatigue-induced degradation of polyurethane elastomers (PUEs) significantly affects their long-term performance, yet the effect of the distribution state of hard domains on their fatigue durability remains poorly understood. In particular, the microstructural evolution under compression fatigue, especially when thermal effects are minimized, is scarcely studied. This study investigates how adjusting the hard segment content (HSC) regulates the distribution and hierarchical organization of hard domains. Low-frequency compression fatigue was employed to isolate purely mechanical damage mechanisms. This allows us to elucidate their influence on the fatigue behavior of PUEs. Characterization results show that the high-HSC sample (PU-H25) forms a continuous and highly ordered spherulitic hard segment network that carries most of the compressive load. However, this rigid architecture is susceptible to stress concentration, leading to progressive degradation of the hard network, and pronounced permanent deformation. In contrast, the low-HSC material (PU-H17) contains hard segments dispersed as isolated physical cross-links within the soft-segment matrix. Under cyclic loading, deformation is primarily accommodated by the soft phase, producing a progressive softening behavior. Although PU-H17 exhibits a larger initial strain, it demonstrates superior elastic recovery. The medium-HSC sample (PU-H21) develops a semicontinuous hard domain morphology that enables cooperative load transfer between hard and soft phases, resulting in the highest structural stability and the slowest fatigue-induced damage evolution. Overall, the results demonstrate that HSC is a key factor governing the fatigue response of PUEs by tailoring their microphase-separated morphology. As HSC increases, the dominant fatigue mechanism shifts from soft-phase-controlled stress dissipation, to cooperative load sharing between hard and soft phases, and finally to hard-phase-dominated load bearing and fracture. These mechanistic insights provide a basis for designing PUEs with tailored fatigue resistance for specific service conditions.
{"title":"Mechanical-Fatigue-Driven Hierarchical Structural Evolution in Polyurethane Elastomers with Different Hard Segment Contents","authors":"Min Wang, Jihang Yu, Yushu Tian, Jiadong Wang, Xuan Qin, Yonglai Lu","doi":"10.1021/acs.macromol.5c03399","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03399","url":null,"abstract":"Fatigue-induced degradation of polyurethane elastomers (PUEs) significantly affects their long-term performance, yet the effect of the distribution state of hard domains on their fatigue durability remains poorly understood. In particular, the microstructural evolution under compression fatigue, especially when thermal effects are minimized, is scarcely studied. This study investigates how adjusting the hard segment content (HSC) regulates the distribution and hierarchical organization of hard domains. Low-frequency compression fatigue was employed to isolate purely mechanical damage mechanisms. This allows us to elucidate their influence on the fatigue behavior of PUEs. Characterization results show that the high-HSC sample (PU-H25) forms a continuous and highly ordered spherulitic hard segment network that carries most of the compressive load. However, this rigid architecture is susceptible to stress concentration, leading to progressive degradation of the hard network, and pronounced permanent deformation. In contrast, the low-HSC material (PU-H17) contains hard segments dispersed as isolated physical cross-links within the soft-segment matrix. Under cyclic loading, deformation is primarily accommodated by the soft phase, producing a progressive softening behavior. Although PU-H17 exhibits a larger initial strain, it demonstrates superior elastic recovery. The medium-HSC sample (PU-H21) develops a semicontinuous hard domain morphology that enables cooperative load transfer between hard and soft phases, resulting in the highest structural stability and the slowest fatigue-induced damage evolution. Overall, the results demonstrate that HSC is a key factor governing the fatigue response of PUEs by tailoring their microphase-separated morphology. As HSC increases, the dominant fatigue mechanism shifts from soft-phase-controlled stress dissipation, to cooperative load sharing between hard and soft phases, and finally to hard-phase-dominated load bearing and fracture. These mechanistic insights provide a basis for designing PUEs with tailored fatigue resistance for specific service conditions.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"88 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116130","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 : 2026-02-05DOI: 10.1021/acs.macromol.5c03088
Noy Cohen
Poly(N-isopropylacrylamide) (PNIPAM) is a temperature-responsive polymer that undergoes large volumetric deformations through a transition from a swollen to a collapsed state at a volume phase transition temperature (VPTT). Locally, these deformations stem from the coil-to-globule transition of individual chains. In this contribution, I revisit the study of Suzuki, A.; Ishii, T. [ J. Chem. Phys.1999, 110, 2289–2296], which demonstrated that a PNIPAM rod can exhibit phase coexistence (i.e., comprise swollen and collapsed domains simultaneously) near the VPTT when subjected to mechanical constraints. Specifically, that paper showed that (1) collapsed domains gradually form in a fixed swollen rod with time and (2) swollen domains can nucleate in a collapsed rod under uniaxial extension. These behaviors originate from the local thermo-mechanical response of the chains, which transition between states in response to the applied mechanical loading. Here, I develop a statistical-mechanics based framework that captures the behavior of individual chains below and above the VPTT and propose a probabilistic model based on the local chain response that sheds light on the underlying mechanisms governing phase nucleation and growth. The model is validated through comparison with experimental data. The findings from this work suggest that in addition to the classical approaches, in which the VPTT is programmed through chemical composition and network topology, the transition can be tuned by mechanical constraints. Furthermore, the proposed framework offers a pathway to actively tailor the VPTT through the exertion of mechanical forces, enabling improved control and performance of PNIPAM hydrogels in modern applications.
{"title":"Phase Coexistence in Thermoresponsive PNIPAM Hydrogels Triggered by Mechanical Forces","authors":"Noy Cohen","doi":"10.1021/acs.macromol.5c03088","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03088","url":null,"abstract":"Poly(<i>N</i>-isopropylacrylamide) (PNIPAM) is a temperature-responsive polymer that undergoes large volumetric deformations through a transition from a swollen to a collapsed state at a volume phase transition temperature (VPTT). Locally, these deformations stem from the coil-to-globule transition of individual chains. In this contribution, I revisit the study of <contrib-group><span>Suzuki, A.</span>; <span>Ishii, T.</span></contrib-group> [ <cite><i>J. Chem. Phys.</i></cite> <span>1999</span>, <em>110</em>, 2289–2296], which demonstrated that a PNIPAM rod can exhibit phase coexistence (i.e., comprise swollen and collapsed domains simultaneously) near the VPTT when subjected to mechanical constraints. Specifically, that paper showed that (1) collapsed domains gradually form in a fixed swollen rod with time and (2) swollen domains can nucleate in a collapsed rod under uniaxial extension. These behaviors originate from the local thermo-mechanical response of the chains, which transition between states in response to the applied mechanical loading. Here, I develop a statistical-mechanics based framework that captures the behavior of individual chains below and above the VPTT and propose a probabilistic model based on the local chain response that sheds light on the underlying mechanisms governing phase nucleation and growth. The model is validated through comparison with experimental data. The findings from this work suggest that in addition to the classical approaches, in which the VPTT is programmed through chemical composition and network topology, the transition can be tuned by mechanical constraints. Furthermore, the proposed framework offers a pathway to actively tailor the VPTT through the exertion of mechanical forces, enabling improved control and performance of PNIPAM hydrogels in modern applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"9 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116129","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 : 2026-02-05DOI: 10.1021/acs.macromol.5c01752
Tianyi Jin, Connor W. Coley, Alfredo Alexander-Katz
Synthetic random heteropolymers (RHPs) offer a versatile platform for mimicking protein-like functions through their sequence and structure ensembles, providing a cost-effective and scalable alternative to natural proteins. Unlike the well-studied energy landscapes of protein folding, the energy landscape of RHP folding, or more generally, collapse, remains largely unexplored. Here, we investigate the energy landscape and structural stability of a recently emergent class of methyl methacrylate-based RHPs. By conducting microsecond-scale atomistic molecular dynamics simulations with umbrella sampling, we propose a hierarchically rugged free energy landscape characterized by high energy barriers separating broad minima with internally rugged basins that permit local structural fluctuations. Identical local sequences are found to be able to adopt diverse conformations. Using XGBoost and SHAP analysis, we identify key contact patterns critical for structural stability. These include specific residue–residue contacts reminiscent of those observed in protein folding, and position-nonspecific interactions, such as contacts between backbone and polar or hydrophobic side groups, which are related to monomer miscibility. This latter relationship resembles the design rules in plastics. Moreover, the inherent diversity of microenvironments in RHPs highlights their potential to incorporate functional ligands, enabling versatile applications such as catalysis. This work elucidates both the similarities and differences among RHPs, proteins, and plastics, providing fundamental insight into the collapse free energy landscape, structural stability, and functional adaptability of RHPs.
{"title":"Energy Landscape and Stability in Random Heteropolymers: Somewhere Between Protein Folding and Plastic Miscibility","authors":"Tianyi Jin, Connor W. Coley, Alfredo Alexander-Katz","doi":"10.1021/acs.macromol.5c01752","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c01752","url":null,"abstract":"Synthetic random heteropolymers (RHPs) offer a versatile platform for mimicking protein-like functions through their sequence and structure ensembles, providing a cost-effective and scalable alternative to natural proteins. Unlike the well-studied energy landscapes of protein folding, the energy landscape of RHP folding, or more generally, collapse, remains largely unexplored. Here, we investigate the energy landscape and structural stability of a recently emergent class of methyl methacrylate-based RHPs. By conducting microsecond-scale atomistic molecular dynamics simulations with umbrella sampling, we propose a hierarchically rugged free energy landscape characterized by high energy barriers separating broad minima with internally rugged basins that permit local structural fluctuations. Identical local sequences are found to be able to adopt diverse conformations. Using XGBoost and SHAP analysis, we identify key contact patterns critical for structural stability. These include specific residue–residue contacts reminiscent of those observed in protein folding, and position-nonspecific interactions, such as contacts between backbone and polar or hydrophobic side groups, which are related to monomer miscibility. This latter relationship resembles the design rules in plastics. Moreover, the inherent diversity of microenvironments in RHPs highlights their potential to incorporate functional ligands, enabling versatile applications such as catalysis. This work elucidates both the similarities and differences among RHPs, proteins, and plastics, providing fundamental insight into the collapse free energy landscape, structural stability, and functional adaptability of RHPs.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"287 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116120","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 : 2026-02-05DOI: 10.1021/acs.macromol.5c02814
Jaechul Ju, Ryan C. Hayward
Cocontinuous polymeric nanomaterials have gained attention for their ability to preserve distinct properties of constituent microphases within a single material. Randomly linked copolymer networks have shown very wide stability windows for disordered cocontinuous phases (extending over ≈ 30 wt % in composition), but the reliance on a network architecture prevents subsequent solution- or melt-processing. Furthermore, the key factors contributing to cocontinuity have remained unclear. We recently found that randomly linked star copolymers (RSCs) can exhibit a cocontinuous window as wide as 25 wt % in the case of 4-arm stars, suggesting that while a network architecture is not essential for the formation of disordered cocontinuous phases, the presence of random elastic forces in such architectures may indeed facilitate their formation. In addition, the behavior was found to be highly sensitive to arm number, with 6-arm RSCs exhibiting almost no cocontinuous phase. These results raised a key mechanistic question regarding the contribution of random elastic forces, originating from strands that bridge between junctions, in stabilizing disordered cocontinuous phases. In the current study, we synthesized randomly linked branched copolymers (RBCs) of polystyrene (PS) and poly(D,L-lactic acid) (PLA), which represent an intermediate architecture between networks and stars. This approach allows for the introduction of elastic contributions from strands bridging between different junctions, while still maintaining the processability advantages of a non-network architecture. The cocontinuous regions of the PS/PLA RBCs, with varying polymer and linker functionalities (fp and fl, respectively), were characterized by small-angle X-ray scattering, gravimetry, and scanning electron microscopy. We found that the cocontinuous windows of RBCs typically expanded with increasing elastic contributions and exhibited reduced sensitivity to junction-functionality compared to RSCs. Notably, RBCs with fp = 1.50 and fl = 3, which had large molecular weights due to proximity to the gel point, achieved a cocontinuous window of ≈ 34 wt %, which is almost twice as wide as analogous 3-arm RSCs and comparable to randomly linked networks. Leveraging this robust cocontinuity and solution-processability, we fabricated a film of interconnected nanoporous PS.
{"title":"Microphase Separation of Randomly Linked Branched Polystyrene/Polylactic Acid for Formation of Cocontinuous Nanostructures","authors":"Jaechul Ju, Ryan C. Hayward","doi":"10.1021/acs.macromol.5c02814","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02814","url":null,"abstract":"Cocontinuous polymeric nanomaterials have gained attention for their ability to preserve distinct properties of constituent microphases within a single material. Randomly linked copolymer networks have shown very wide stability windows for disordered cocontinuous phases (extending over ≈ 30 wt % in composition), but the reliance on a network architecture prevents subsequent solution- or melt-processing. Furthermore, the key factors contributing to cocontinuity have remained unclear. We recently found that randomly linked star copolymers (RSCs) can exhibit a cocontinuous window as wide as 25 wt % in the case of 4-arm stars, suggesting that while a network architecture is not essential for the formation of disordered cocontinuous phases, the presence of random elastic forces in such architectures may indeed facilitate their formation. In addition, the behavior was found to be highly sensitive to arm number, with 6-arm RSCs exhibiting almost no cocontinuous phase. These results raised a key mechanistic question regarding the contribution of random elastic forces, originating from strands that bridge between junctions, in stabilizing disordered cocontinuous phases. In the current study, we synthesized randomly linked branched copolymers (RBCs) of polystyrene (PS) and poly(D,L-lactic acid) (PLA), which represent an intermediate architecture between networks and stars. This approach allows for the introduction of elastic contributions from strands bridging between different junctions, while still maintaining the processability advantages of a non-network architecture. The cocontinuous regions of the PS/PLA RBCs, with varying polymer and linker functionalities (<i>f</i><sub>p</sub> and <i>f</i><sub>l</sub>, respectively), were characterized by small-angle X-ray scattering, gravimetry, and scanning electron microscopy. We found that the cocontinuous windows of RBCs typically expanded with increasing elastic contributions and exhibited reduced sensitivity to junction-functionality compared to RSCs. Notably, RBCs with <i>f</i><sub>p</sub> = 1.50 and <i>f</i><sub>l</sub> = 3, which had large molecular weights due to proximity to the gel point, achieved a cocontinuous window of ≈ 34 wt %, which is almost twice as wide as analogous 3-arm RSCs and comparable to randomly linked networks. Leveraging this robust cocontinuity and solution-processability, we fabricated a film of interconnected nanoporous PS.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"159 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116084","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 : 2026-02-04DOI: 10.1021/acs.macromol.5c03180
Somesh Kurahatti,Mariano E. Brito,David Beyer,Christian Holm
Elastic modulus, G, and equilibrium swelling ratio, QV, are two properties of hydrogels, which are linked by the scaling law G ∼ QVβ, where β = −1 and −9/4 in the low- and high-salt limits, respectively. Tuning them independently would enable the optimization of the material design for a wide variety of distinct applications. In this work, we investigate several possibilities to achieve this using various network heterogeneities. We employ implicit solvent coarse-grained molecular dynamics simulations to explore mechanical, structural, and thermodynamic properties of hydrogels with varying topologies in comparison to a regular reference gel. We explore regular gels with tetrafunctional cross-linkers arranged in a diamond-lattice fashion, which we take as a reference gel, together with bottlebrush gels, gels with dangling ends, and gels coexisting with floating chains. We observe that incorporating dangling ends changes the swelling ratio and bulk modulus following the relation obtained from the regular reference gel, whereas the bottlebrush and floating-chain gels show stronger deviations. Specifically, floating-chain gels resulted in higher moduli and higher swelling ratios, while bottlebrush gels resulted in lower moduli and lower swelling ratios than the regular counterparts. Concomitantly, a clear change in salt partitioning was observed for various hydrogel architectures. Our results show new ways to optimize the elastic modulus of gels with respect to their swelling behavior and allow for the optimization and on-demand design of hydrogels.
{"title":"Effect of Different Network Topologies on Swelling and Mechanical Properties of Polyelectrolyte Hydrogels","authors":"Somesh Kurahatti,Mariano E. Brito,David Beyer,Christian Holm","doi":"10.1021/acs.macromol.5c03180","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03180","url":null,"abstract":"Elastic modulus, G, and equilibrium swelling ratio, QV, are two properties of hydrogels, which are linked by the scaling law G ∼ QVβ, where β = −1 and −9/4 in the low- and high-salt limits, respectively. Tuning them independently would enable the optimization of the material design for a wide variety of distinct applications. In this work, we investigate several possibilities to achieve this using various network heterogeneities. We employ implicit solvent coarse-grained molecular dynamics simulations to explore mechanical, structural, and thermodynamic properties of hydrogels with varying topologies in comparison to a regular reference gel. We explore regular gels with tetrafunctional cross-linkers arranged in a diamond-lattice fashion, which we take as a reference gel, together with bottlebrush gels, gels with dangling ends, and gels coexisting with floating chains. We observe that incorporating dangling ends changes the swelling ratio and bulk modulus following the relation obtained from the regular reference gel, whereas the bottlebrush and floating-chain gels show stronger deviations. Specifically, floating-chain gels resulted in higher moduli and higher swelling ratios, while bottlebrush gels resulted in lower moduli and lower swelling ratios than the regular counterparts. Concomitantly, a clear change in salt partitioning was observed for various hydrogel architectures. Our results show new ways to optimize the elastic modulus of gels with respect to their swelling behavior and allow for the optimization and on-demand design of hydrogels.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"1 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146111073","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 : 2026-02-04DOI: 10.1021/acs.macromol.5c02877
Jelle De Ceulaer,Ruth Cardinaels,Peter Van Puyvelde
Dynamic covalent networks (DCNs) combine thermoset-like performance with thermoplastic reprocessability through dynamic covalent chemistry. Their properties are dictated by their microstructure, which is determined by the interplay between reversible covalent reactions and fixation mechanisms, such as crystallization. Here, the interplay of crystallization and cross-linking in poly(ε-caprolactone)-based DCNs is investigated by varying PCL precursor functionality from linear 2-functional to star-shaped 4- and 6-functional architectures. This design enables distinct cases ranging from linear chain extension to network formation occurring on similar time scales as crystallization. Nonisothermal and isothermal studies reveal that cross-linking slows down crystallization, lowers crystallization peak temperatures, and promotes secondary crystallization. Morphological analysis shows more irregular spherulites, while kinetic evaluation confirms adverse effects of cross-linking on both nucleation and crystal growth, except in short linear chains where nucleation is enhanced. In that case, molecular weight effects during cross-linking are likely to dominate the crystallization behavior. These results provide structural insight into tailoring crystallizable DCNs.
{"title":"Competing Crystallization and Cross-Linking Behavior in Multifunctional Poly(ε-Caprolactone)-Based Dynamic Covalent Networks","authors":"Jelle De Ceulaer,Ruth Cardinaels,Peter Van Puyvelde","doi":"10.1021/acs.macromol.5c02877","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02877","url":null,"abstract":"Dynamic covalent networks (DCNs) combine thermoset-like performance with thermoplastic reprocessability through dynamic covalent chemistry. Their properties are dictated by their microstructure, which is determined by the interplay between reversible covalent reactions and fixation mechanisms, such as crystallization. Here, the interplay of crystallization and cross-linking in poly(ε-caprolactone)-based DCNs is investigated by varying PCL precursor functionality from linear 2-functional to star-shaped 4- and 6-functional architectures. This design enables distinct cases ranging from linear chain extension to network formation occurring on similar time scales as crystallization. Nonisothermal and isothermal studies reveal that cross-linking slows down crystallization, lowers crystallization peak temperatures, and promotes secondary crystallization. Morphological analysis shows more irregular spherulites, while kinetic evaluation confirms adverse effects of cross-linking on both nucleation and crystal growth, except in short linear chains where nucleation is enhanced. In that case, molecular weight effects during cross-linking are likely to dominate the crystallization behavior. These results provide structural insight into tailoring crystallizable DCNs.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"24 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146111074","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}
A continuous network with short-range aggregation structures in an amorphous matrix is widely recognized for achieving optimal electronic and mechanical performance of conjugated polymer films. The size and structural order of these aggregates critically determine the ability to accommodate and dissipate strain without disrupting the charge transport pathways. Here, we systematically investigated the effect of polymer chain dynamics on the evolution of aggregation structure for the conjugated polymer poly(indacenodithiophene-co-benzothiadiazole) (IDTBT) by controlling the annealing temperature (Ta). In the as-cast film, the polymer backbone remains kinetically trapped in a distorted conformation, leading to a loosely packed and disordered morphology. Thermal annealing at 100 °C, between the backbone glass transition temperatures (Tg) and the disaggregation temperature (Tdisagg), activates the segment motion, enabling reorganization into small, short-range ordered aggregates with an extended conformation. When annealed at 260 °C (Ta > Tdisagg), full chain mobility permits assembly into larger, more ordered aggregates with dense molecular packing. Consequently, the charge mobility increases from 0.92 cm2 V–1 s–1 in the as-cast film to 3.14 cm2 V–1 s–1 after annealing at 260 °C. Under strain, the film annealed at 100 °C retains its short-range aggregates, which facilitates efficient stress dissipation through interlayer slip and preserves charge mobility. In contrast, the film annealed at 260 °C exhibits premature fracture of the large ordered aggregates accompanied by restricted chain alignment. As a result, the film annealed at 100 °C maintains a charge mobility of 0.86 cm2 V–1 s–1 under 100% strain, whereas the 260 °C-annealed film exhibits a substantially lower mobility of 0.14 cm2 V–1 s–1. These results underscore the critical role of short-range aggregation structures in achieving high-performance stretchable conjugated polymer films.
{"title":"The Short-Range Ordered Aggregation Structures Obtained by Controlling the Chain Segment Movement for Stretchable IDTBT Films","authors":"Junhang Li,Zicheng Ding,Zehao Wang,Yiting Liu,Tianya Jin,Xueting Yi,Rui Chen,Zhongxiang Peng,Rui Zhang,Yanchun Han","doi":"10.1021/acs.macromol.5c03533","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03533","url":null,"abstract":"A continuous network with short-range aggregation structures in an amorphous matrix is widely recognized for achieving optimal electronic and mechanical performance of conjugated polymer films. The size and structural order of these aggregates critically determine the ability to accommodate and dissipate strain without disrupting the charge transport pathways. Here, we systematically investigated the effect of polymer chain dynamics on the evolution of aggregation structure for the conjugated polymer poly(indacenodithiophene-co-benzothiadiazole) (IDTBT) by controlling the annealing temperature (Ta). In the as-cast film, the polymer backbone remains kinetically trapped in a distorted conformation, leading to a loosely packed and disordered morphology. Thermal annealing at 100 °C, between the backbone glass transition temperatures (Tg) and the disaggregation temperature (Tdisagg), activates the segment motion, enabling reorganization into small, short-range ordered aggregates with an extended conformation. When annealed at 260 °C (Ta > Tdisagg), full chain mobility permits assembly into larger, more ordered aggregates with dense molecular packing. Consequently, the charge mobility increases from 0.92 cm2 V–1 s–1 in the as-cast film to 3.14 cm2 V–1 s–1 after annealing at 260 °C. Under strain, the film annealed at 100 °C retains its short-range aggregates, which facilitates efficient stress dissipation through interlayer slip and preserves charge mobility. In contrast, the film annealed at 260 °C exhibits premature fracture of the large ordered aggregates accompanied by restricted chain alignment. As a result, the film annealed at 100 °C maintains a charge mobility of 0.86 cm2 V–1 s–1 under 100% strain, whereas the 260 °C-annealed film exhibits a substantially lower mobility of 0.14 cm2 V–1 s–1. These results underscore the critical role of short-range aggregation structures in achieving high-performance stretchable conjugated polymer films.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"8 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146111072","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 : 2026-02-04DOI: 10.1021/acs.macromol.5c02445
Chengwang Shi,Xiaodong Li,Hao Jiang,Xing Su,Xiaoxuan Wang,Xufeng Zhang,Meishuai Zou
Imine-functionalized epoxy resins have become a research hotspot due to their degradable and recyclable properties. However, the inherent thermodynamic instability of imine bonds poses a challenge in developing multifunctional novel epoxy resins that exhibit high strength and toughness, low-temperature resistance, and environmental stability. In this study, a molecular structure engineering strategy was employed to construct a dual-dynamic supramolecular acylhydrazone-functionalized epoxy network-EPCAN-5. Benefiting from the synergistic cross-linking effect between the reversible hydrogen-bonding network in the gradient-energy structure and the covalent cross-linking network with a rigid-flexible design, this material exhibits ultrahigh strength and toughness (tensile strength of 115 MPa, elongation at break of 12.3%, toughness of 11.01 MJ/m3). It maintains a tensile strength of 140 MPa with 6% elongation even at an extremely low temperature of −50 °C, and retains excellent mechanical stability and flexibility even when immersed in liquid nitrogen (−196 °C). Furthermore, it demonstrates outstanding resistance to water and weak acids, addressing the technical challenge of performance degradation in imine-based epoxy materials under service conditions. The gradient-energy hydrogen-bonding structure endows EPCAN-5 with excellent programmable heat-driven shape memory functionality; a designed hook structure can lift up to 5000 times its own weight and automatically release the load upon reaching the temperature threshold. Additionally, the material can be fully recovered via a catalyst-free closed-loop process, with the repolymerized material retaining 99% of the original mechanical properties. In summary, this work successfully constructed a covalent cross-linking system that integrates gradient hydrogen bonds, reversible covalent bonds, and a balanced combination of rigidity and flexibility. This system exhibits notable advantages, including high strength and toughness, low-temperature resistance, shape memory capability, and environmental stability.
{"title":"Highly Robust and Ultralow Temperature Resistant Epoxy Network Based on Acylhydrazone Bonds: Water Resistant, Shape Memory and Closed-Loop Recyclable","authors":"Chengwang Shi,Xiaodong Li,Hao Jiang,Xing Su,Xiaoxuan Wang,Xufeng Zhang,Meishuai Zou","doi":"10.1021/acs.macromol.5c02445","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02445","url":null,"abstract":"Imine-functionalized epoxy resins have become a research hotspot due to their degradable and recyclable properties. However, the inherent thermodynamic instability of imine bonds poses a challenge in developing multifunctional novel epoxy resins that exhibit high strength and toughness, low-temperature resistance, and environmental stability. In this study, a molecular structure engineering strategy was employed to construct a dual-dynamic supramolecular acylhydrazone-functionalized epoxy network-EPCAN-5. Benefiting from the synergistic cross-linking effect between the reversible hydrogen-bonding network in the gradient-energy structure and the covalent cross-linking network with a rigid-flexible design, this material exhibits ultrahigh strength and toughness (tensile strength of 115 MPa, elongation at break of 12.3%, toughness of 11.01 MJ/m3). It maintains a tensile strength of 140 MPa with 6% elongation even at an extremely low temperature of −50 °C, and retains excellent mechanical stability and flexibility even when immersed in liquid nitrogen (−196 °C). Furthermore, it demonstrates outstanding resistance to water and weak acids, addressing the technical challenge of performance degradation in imine-based epoxy materials under service conditions. The gradient-energy hydrogen-bonding structure endows EPCAN-5 with excellent programmable heat-driven shape memory functionality; a designed hook structure can lift up to 5000 times its own weight and automatically release the load upon reaching the temperature threshold. Additionally, the material can be fully recovered via a catalyst-free closed-loop process, with the repolymerized material retaining 99% of the original mechanical properties. In summary, this work successfully constructed a covalent cross-linking system that integrates gradient hydrogen bonds, reversible covalent bonds, and a balanced combination of rigidity and flexibility. This system exhibits notable advantages, including high strength and toughness, low-temperature resistance, shape memory capability, and environmental stability.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"19 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146111075","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 : 2026-02-04DOI: 10.1021/acs.macromol.5c03218
Hao Cai, Huan Gao, Zhe Ma, Li Pan, Yuesheng Li
Polypropylene-based elastomers (PP-Es) offer superior mechanical properties, heat resistance, and compatibility with PP matrices compared to polyethylene-based elastomers (PE-Es). This study developed high-performance PP-Es with low α-olefin consumption through catalyst selection and chain structure design. Employing a moderately stereo- and regioselective bis(phenolate-ether) hafnium catalyst, as opposed to a highly selective metallocene catalyst, afforded PP-Es with higher molecular weight, enhanced mechanical properties, and similar crystallinity at a reduced comonomer requirement. When used as tougheners for brittle iPP, PP-Es significantly enhance tensile performance, markedly increasing elongation at break, far exceeding commercial PE-E systems (e.g., Engage 7447 and 8842), while maintaining high strength and transparency. Added to incompatible HDPE/iPP blends (30/70 and 50/50), PP-Es effectively compatibilized the phases, significantly increasing elongation at break while largely retaining strength. Furthermore, the compatibilization behaviors of PP-Es and PE-Es were compared across different HDPE/iPP ratios, together with their tensile and impact properties, establishing a clear link between compatibilizer chain structure, phase composition, and performance enhancement.
{"title":"Designing Resource-Efficient Polypropylene-Based Elastomers via Moderately Selective Catalyst for Toughening and Compatibilization","authors":"Hao Cai, Huan Gao, Zhe Ma, Li Pan, Yuesheng Li","doi":"10.1021/acs.macromol.5c03218","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03218","url":null,"abstract":"Polypropylene-based elastomers (PP-Es) offer superior mechanical properties, heat resistance, and compatibility with PP matrices compared to polyethylene-based elastomers (PE-Es). This study developed high-performance PP-Es with low α-olefin consumption through catalyst selection and chain structure design. Employing a moderately stereo- and regioselective bis(phenolate-ether) hafnium catalyst, as opposed to a highly selective metallocene catalyst, afforded PP-Es with higher molecular weight, enhanced mechanical properties, and similar crystallinity at a reduced comonomer requirement. When used as tougheners for brittle <i>i</i>PP, PP-Es significantly enhance tensile performance, markedly increasing elongation at break, far exceeding commercial PE-E systems (e.g., Engage 7447 and 8842), while maintaining high strength and transparency. Added to incompatible HDPE/<i>i</i>PP blends (30/70 and 50/50), PP-Es effectively compatibilized the phases, significantly increasing elongation at break while largely retaining strength. Furthermore, the compatibilization behaviors of PP-Es and PE-Es were compared across different HDPE/<i>i</i>PP ratios, together with their tensile and impact properties, establishing a clear link between compatibilizer chain structure, phase composition, and performance enhancement.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"19 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116085","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 : 2026-02-04DOI: 10.1021/acs.macromol.5c03531
Jens Van Hoorde,Quinten Thijssen,Nezha Badi,Filip E. Du Prez
Sequence-defined macromolecules provide uniform chain composition and precise control over monomer order, yet their implementation in materials science has been constrained by challenges in achieving their scalable synthesis. Here, we report the multigram-scale (i.e., 120 g) preparation of telechelic sequence-defined oligourethanes incorporating distinct hydrogen-bonding motifs and their subsequent cross-linking into structurally well-defined model networks. This scalable access to such uniform structures enables comprehensive structural, thermal, and mechanical characterization, including precise analysis of network integrity through network-disassembly spectrometry. This in-depth analysis revealed clear correlations between the molecular design of the cross-linker and bulk network properties, including swelling behavior, hydrophilicity, and Young’s modulus. Importantly, the scalability of these macromolecules also allowed integration with volumetric 3D printing as a representative high-volume fabrication method, demonstrating that molecular-level sequence control can be reliably translated into advanced manufacturing applications.
{"title":"Linking Molecular Sequence to Material Performance: Model Networks and Volumetric 3D Printing of Sequence-Defined Oligourethanes","authors":"Jens Van Hoorde,Quinten Thijssen,Nezha Badi,Filip E. Du Prez","doi":"10.1021/acs.macromol.5c03531","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03531","url":null,"abstract":"Sequence-defined macromolecules provide uniform chain composition and precise control over monomer order, yet their implementation in materials science has been constrained by challenges in achieving their scalable synthesis. Here, we report the multigram-scale (i.e., 120 g) preparation of telechelic sequence-defined oligourethanes incorporating distinct hydrogen-bonding motifs and their subsequent cross-linking into structurally well-defined model networks. This scalable access to such uniform structures enables comprehensive structural, thermal, and mechanical characterization, including precise analysis of network integrity through network-disassembly spectrometry. This in-depth analysis revealed clear correlations between the molecular design of the cross-linker and bulk network properties, including swelling behavior, hydrophilicity, and Young’s modulus. Importantly, the scalability of these macromolecules also allowed integration with volumetric 3D printing as a representative high-volume fabrication method, demonstrating that molecular-level sequence control can be reliably translated into advanced manufacturing applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"41 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146111071","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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