Pub Date : 2026-01-26DOI: 10.1021/acs.macromol.5c03344
Dietrich Gloger, János Molnár, Dietmar Salaberger, Davide Tranchida, Markus Gahleitner, Wolfgang H. Binder, René Androsch
We demonstrate that long-chain branched polypropylene (LCB PP) exhibits pronounced melt memory above the equilibrium melting point due to topological constraints and gel-like structures that slow the relaxation of non-equilibrium chain states. These states, formed during synthesis and subsequent melt processing, act as self-nuclei in differential scanning calorimetry (DSC) experiments and persist beyond the conventional 5 min equilibration used in standard DSC protocols. The decay of self-nuclei, monitored via the isothermal crystallization rate, follows a power-law dependence with the equilibration time. This behavior agrees with diffusive relaxation of non-equilibrium clusters in a topologically complex environment. Morphological analyses show that self-nucleation produces nucleation densities (Nd) up to 1011 cm–3, which suppresses spherulitic growth and induces anisotropic lamellar textures. The self-nuclei are most effectively reduced in a prior solution treatment of the polymer, which decreases Nd and crystallization rate but also increases the viscoelastic relaxation time, demonstrating the link between melt structure and crystallization.
{"title":"Long Memory in Large Molecules: Self-Nucleation in Long-Chain Branched Polypropylene Melts","authors":"Dietrich Gloger, János Molnár, Dietmar Salaberger, Davide Tranchida, Markus Gahleitner, Wolfgang H. Binder, René Androsch","doi":"10.1021/acs.macromol.5c03344","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03344","url":null,"abstract":"We demonstrate that long-chain branched polypropylene (LCB PP) exhibits pronounced melt memory above the equilibrium melting point due to topological constraints and gel-like structures that slow the relaxation of non-equilibrium chain states. These states, formed during synthesis and subsequent melt processing, act as self-nuclei in differential scanning calorimetry (DSC) experiments and persist beyond the conventional 5 min equilibration used in standard DSC protocols. The decay of self-nuclei, monitored via the isothermal crystallization rate, follows a power-law dependence with the equilibration time. This behavior agrees with diffusive relaxation of non-equilibrium clusters in a topologically complex environment. Morphological analyses show that self-nucleation produces nucleation densities (<i>N</i><sub>d</sub>) up to 10<sup>11</sup> cm<sup>–3</sup>, which suppresses spherulitic growth and induces anisotropic lamellar textures. The self-nuclei are most effectively reduced in a prior solution treatment of the polymer, which decreases <i>N</i><sub>d</sub> and crystallization rate but also increases the viscoelastic relaxation time, demonstrating the link between melt structure and crystallization.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"24 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044769","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 : 2026-01-26DOI: 10.1021/acs.macromol.5c03019
Shin Inagaki,Hideki Abe
The development of fully metal-free strategies for the synthesis and functionalization of polymers is crucial for advancing sustainable materials. This study introduces a platform that integrates metal-free reversible addition–fragmentation chain-transfer (RAFT) polymerization with sulfur(VI) fluoride exchange (SuFEx) chemistry to enable the controlled polymerization and postpolymerization side-chain modification of renewable polymers. Silyl-protected poly(vinylphenol) (PSVP)s and poly(vinyl catechol) (PSVC) derived from cinnamic acid analogs were synthesized and subsequently functionalized with a range of sulfonyl fluorides bearing electron-donating or electron-withdrawing substituents. High degrees of modification were achieved for para-substituted PSVP, while meta-substituted PSVP and their corresponding block copolymers exhibited high conversions with minimal side reactions. By contrast, ortho-substituted PSVP and PSVC systems generally exhibited moderate efficiencies, consistent with steric hindrance. This fully metal-free sequence provides a sustainable and versatile strategy for the functionalization of biobased polymers, expanding the scope of SuFEx chemistry and contributing to the development of environmentally sustainable polymer materials.
{"title":"SuFEx Chemistry Enables Sustainable Side-Chain Modification of Renewable Phenylpropanoid Polymers","authors":"Shin Inagaki,Hideki Abe","doi":"10.1021/acs.macromol.5c03019","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03019","url":null,"abstract":"The development of fully metal-free strategies for the synthesis and functionalization of polymers is crucial for advancing sustainable materials. This study introduces a platform that integrates metal-free reversible addition–fragmentation chain-transfer (RAFT) polymerization with sulfur(VI) fluoride exchange (SuFEx) chemistry to enable the controlled polymerization and postpolymerization side-chain modification of renewable polymers. Silyl-protected poly(vinylphenol) (PSVP)s and poly(vinyl catechol) (PSVC) derived from cinnamic acid analogs were synthesized and subsequently functionalized with a range of sulfonyl fluorides bearing electron-donating or electron-withdrawing substituents. High degrees of modification were achieved for para-substituted PSVP, while meta-substituted PSVP and their corresponding block copolymers exhibited high conversions with minimal side reactions. By contrast, ortho-substituted PSVP and PSVC systems generally exhibited moderate efficiencies, consistent with steric hindrance. This fully metal-free sequence provides a sustainable and versatile strategy for the functionalization of biobased polymers, expanding the scope of SuFEx chemistry and contributing to the development of environmentally sustainable polymer materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"40 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146045012","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}
Developing high-performance polyurethane (PU) elastomers requires overcoming the inherent trade-off between strength and toughness through precise control of the microphase separation morphology. Advances in nanostructure control and nondestructive microstructural detection are therefore essential. Herein, we report a hyperbranched PU elastomer (PU-HPAEx) synthesized using hyperbranched poly(amino ester) (HPAE) as a dual-function macromonomer that acts simultaneously as a chain extender and a nonconventional fluorescent probe. The hyperbranched architecture creates a three-dimensional network enriched with high-density sacrificial hydrogen bonds (H-bonds) and a well-defined microphase-separated morphology, resulting in exceptional strength (65.80 MPa), elongation (1031.70%), and toughness (185.3 MJ m–3)─overcoming classical strength–toughness conflicts. In addition, the hyperbranched topology promotes efficient cluster-triggered emission (CTE) via through-space conjugation (TSC), endowing PU-HPAEx with exceptionally strong fluorescence (quantum yield 11.16%). Critically, HPAE serves as an intrinsic fluorescent probe, enabling in situ visualization of micrometer-scale phase separation and its dynamic evolution, thereby providing key insights into the morphology–performance relationship. Furthermore, HPAE exhibits stimuli-responsive fluorescence under both mechanical strain and humidity, highlighting its potential application in smart sensing. By leveraging topological structure regulation, this work successfully establishes a novel strategy for fluorescent PU elastomers that integrates high performance with nondestructive visualization of microphase morphology.
{"title":"In Situ Visualization of Microphase Separation in High-Performance Hyperbranched Polyurethane","authors":"Jingyuan Wei,Yufei Zhang,Huan Ma,Jia Li,Junzhuo Cheng,Haotian Ma,Shenggui Du,Kai Cheng,Hefeng Zhang,Tianqi Zhou,Yu Jiang,Daohong Zhang,Nikos Hadjichristidis","doi":"10.1021/acs.macromol.5c02875","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02875","url":null,"abstract":"Developing high-performance polyurethane (PU) elastomers requires overcoming the inherent trade-off between strength and toughness through precise control of the microphase separation morphology. Advances in nanostructure control and nondestructive microstructural detection are therefore essential. Herein, we report a hyperbranched PU elastomer (PU-HPAEx) synthesized using hyperbranched poly(amino ester) (HPAE) as a dual-function macromonomer that acts simultaneously as a chain extender and a nonconventional fluorescent probe. The hyperbranched architecture creates a three-dimensional network enriched with high-density sacrificial hydrogen bonds (H-bonds) and a well-defined microphase-separated morphology, resulting in exceptional strength (65.80 MPa), elongation (1031.70%), and toughness (185.3 MJ m–3)─overcoming classical strength–toughness conflicts. In addition, the hyperbranched topology promotes efficient cluster-triggered emission (CTE) via through-space conjugation (TSC), endowing PU-HPAEx with exceptionally strong fluorescence (quantum yield 11.16%). Critically, HPAE serves as an intrinsic fluorescent probe, enabling in situ visualization of micrometer-scale phase separation and its dynamic evolution, thereby providing key insights into the morphology–performance relationship. Furthermore, HPAE exhibits stimuli-responsive fluorescence under both mechanical strain and humidity, highlighting its potential application in smart sensing. By leveraging topological structure regulation, this work successfully establishes a novel strategy for fluorescent PU elastomers that integrates high performance with nondestructive visualization of microphase morphology.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"64 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146045015","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 : 2026-01-26DOI: 10.1021/acs.macromol.5c03069
Yen-Ling Kuan,Yu-Chun Chiu,Yun-Sheng Ye,Shiao-Wei Kuo
In this study, the chain end of a reversible addition–fragmentation chain transfer (RAFT) polymerization agent of poly(cyclohexene carbonate) (PCHC) was synthesized via the ring-opening copolymerization of CO2 and cyclohexene oxide (CHO) by using s-dodecyl-s’-(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (DDMAT) as a chain transfer agent. Various block copolymers of poly(cyclohexene carbonate)-b-poly(styrene-alt-N-(hydroxyphenyl)maleimide) (PCHC-b-PSHPMI) were subsequently synthesized by the RAFT copolymerization of styrene and N-(hydroxyphenyl)maleimide (HPMI) in the presence of azobis(isobutyronitrile) (AIBN), which were characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). DSC thermal analyses indicated that the single Tg values were observed for all PCHC-b-PSHPMI copolymers, indicating miscible behavior, and the Tg value was 194 °C for the PCHC-b-PSHPMI78 copolymer. One- and two-dimensional (2D) FTIR spectroscopy revealed that these PCHC-b-PSHPMI copolymers actually provide relatively weak intermolecular O–H···O═C hydrogen bonding, which was attenuated by the self-association of hydrogen bonding within the pure PCHC and pure PSHPMI segments. In the solid-state 13C NMR spectra, a pronounced chemical shift variation of the C–OH and C═O units of the PSHPMI segment and C═O units of the PCHC segment was also observed, which is attributable to the intermolecular hydrogen interactions in these PCHC-b-PSHPMI copolymers. Rotating-frame 1H spin–lattice relaxation [T1ρ(H)] analyses also indicated the complete miscible behavior of these block copolymers within the 2–3 nm length scale, and the relaxation times exhibited positive deviations from the linear predicted rule. These results suggest that the loose chain structure was formed because of the weaker intermolecular hydrogen bonding between the PCHC and PSHPMI segments in the block copolymers.
{"title":"Highly Thermally Stable and Miscible CO2-Based Block Copolymers by the Combination of Ring-Opening and RAFT Copolymerizations through Mediated Hydrogen Bonding Interactions","authors":"Yen-Ling Kuan,Yu-Chun Chiu,Yun-Sheng Ye,Shiao-Wei Kuo","doi":"10.1021/acs.macromol.5c03069","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03069","url":null,"abstract":"In this study, the chain end of a reversible addition–fragmentation chain transfer (RAFT) polymerization agent of poly(cyclohexene carbonate) (PCHC) was synthesized via the ring-opening copolymerization of CO2 and cyclohexene oxide (CHO) by using s-dodecyl-s’-(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (DDMAT) as a chain transfer agent. Various block copolymers of poly(cyclohexene carbonate)-b-poly(styrene-alt-N-(hydroxyphenyl)maleimide) (PCHC-b-PSHPMI) were subsequently synthesized by the RAFT copolymerization of styrene and N-(hydroxyphenyl)maleimide (HPMI) in the presence of azobis(isobutyronitrile) (AIBN), which were characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). DSC thermal analyses indicated that the single Tg values were observed for all PCHC-b-PSHPMI copolymers, indicating miscible behavior, and the Tg value was 194 °C for the PCHC-b-PSHPMI78 copolymer. One- and two-dimensional (2D) FTIR spectroscopy revealed that these PCHC-b-PSHPMI copolymers actually provide relatively weak intermolecular O–H···O═C hydrogen bonding, which was attenuated by the self-association of hydrogen bonding within the pure PCHC and pure PSHPMI segments. In the solid-state 13C NMR spectra, a pronounced chemical shift variation of the C–OH and C═O units of the PSHPMI segment and C═O units of the PCHC segment was also observed, which is attributable to the intermolecular hydrogen interactions in these PCHC-b-PSHPMI copolymers. Rotating-frame 1H spin–lattice relaxation [T1ρ(H)] analyses also indicated the complete miscible behavior of these block copolymers within the 2–3 nm length scale, and the relaxation times exhibited positive deviations from the linear predicted rule. These results suggest that the loose chain structure was formed because of the weaker intermolecular hydrogen bonding between the PCHC and PSHPMI segments in the block copolymers.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"7 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146045011","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}
Developing high-performance polyurethane (PU) elastomers requires overcoming the inherent trade-off between strength and toughness through precise control of the microphase separation morphology. Advances in nanostructure control and nondestructive microstructural detection are therefore essential. Herein, we report a hyperbranched PU elastomer (PU-HPAEx) synthesized using hyperbranched poly(amino ester) (HPAE) as a dual-function macromonomer that acts simultaneously as a chain extender and a nonconventional fluorescent probe. The hyperbranched architecture creates a three-dimensional network enriched with high-density sacrificial hydrogen bonds (H-bonds) and a well-defined microphase-separated morphology, resulting in exceptional strength (65.80 MPa), elongation (1031.70%), and toughness (185.3 MJ m–3)─overcoming classical strength–toughness conflicts. In addition, the hyperbranched topology promotes efficient cluster-triggered emission (CTE) via through-space conjugation (TSC), endowing PU-HPAEx with exceptionally strong fluorescence (quantum yield 11.16%). Critically, HPAE serves as an intrinsic fluorescent probe, enabling in situ visualization of micrometer-scale phase separation and its dynamic evolution, thereby providing key insights into the morphology–performance relationship. Furthermore, HPAE exhibits stimuli-responsive fluorescence under both mechanical strain and humidity, highlighting its potential application in smart sensing. By leveraging topological structure regulation, this work successfully establishes a novel strategy for fluorescent PU elastomers that integrates high performance with nondestructive visualization of microphase morphology.
{"title":"In Situ Visualization of Microphase Separation in High-Performance Hyperbranched Polyurethane","authors":"Jingyuan Wei,Yufei Zhang,Huan Ma,Jia Li,Junzhuo Cheng,Haotian Ma,Shenggui Du,Kai Cheng,Hefeng Zhang,Tianqi Zhou,Yu Jiang,Daohong Zhang,Nikos Hadjichristidis","doi":"10.1021/acs.macromol.5c02875","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02875","url":null,"abstract":"Developing high-performance polyurethane (PU) elastomers requires overcoming the inherent trade-off between strength and toughness through precise control of the microphase separation morphology. Advances in nanostructure control and nondestructive microstructural detection are therefore essential. Herein, we report a hyperbranched PU elastomer (PU-HPAEx) synthesized using hyperbranched poly(amino ester) (HPAE) as a dual-function macromonomer that acts simultaneously as a chain extender and a nonconventional fluorescent probe. The hyperbranched architecture creates a three-dimensional network enriched with high-density sacrificial hydrogen bonds (H-bonds) and a well-defined microphase-separated morphology, resulting in exceptional strength (65.80 MPa), elongation (1031.70%), and toughness (185.3 MJ m–3)─overcoming classical strength–toughness conflicts. In addition, the hyperbranched topology promotes efficient cluster-triggered emission (CTE) via through-space conjugation (TSC), endowing PU-HPAEx with exceptionally strong fluorescence (quantum yield 11.16%). Critically, HPAE serves as an intrinsic fluorescent probe, enabling in situ visualization of micrometer-scale phase separation and its dynamic evolution, thereby providing key insights into the morphology–performance relationship. Furthermore, HPAE exhibits stimuli-responsive fluorescence under both mechanical strain and humidity, highlighting its potential application in smart sensing. By leveraging topological structure regulation, this work successfully establishes a novel strategy for fluorescent PU elastomers that integrates high performance with nondestructive visualization of microphase morphology.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"75 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146045014","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 : 2026-01-26DOI: 10.1021/acs.macromol.5c02962
Thanh-Tam Mai, Daichi Nozaki, Yuki Tokudome, Katsuhiko Tsunoda, Kenji Urayama
We investigate the coupled evolution of heterogeneous strain, crystallinity, and stress fields in natural rubber (NR) sheets containing a circular hole during uniaxial stretching, with a focus on how strain-induced crystallization (SIC) influences local stress concentration at structural discontinuities. By high-resolution digital image correlation, an empirical strain-crystallinity relationship and a hyperelasticity analysis firmly grounded in stress–strain data obtained under diverse deformation modes, we quantitatvely map the spatial distributions of strain, SIC, and stress in the extreme vicinity (≈0.2 mm) of the defect. Local strain concentration at the lateral hole edges triggers pronounced SIC, resulting in strong stiffening and a stress concentration factor (Kt*) as high as 4.5─significantly exceeding classical elastic predictions. Upon further stretching, Kt* plateaus, eventually as SIC develops in the far-field region, promoting a more homogeneous stress distribution. The SIC-induced stiffening also generates a highly anisotropic stress field near the hole edges due to preferential reinforcement along the crystalline orientation. The localized SIC causes characteristic hole-shape evolution, where the hole becomes increasingly elongated along the stretching axis compared with the fully amorphous state. These findings elucidate the fundamental interplay between SIC and local stress concentration in elastomers with structural discontinuities and provide mechanistic insights for designing defect-tolerant, high-toughness rubber materials.
{"title":"Coupled Evolution of Local Stress and Strain-Induced Crystallization Near a Circular Defect in Stretched Natural Rubber","authors":"Thanh-Tam Mai, Daichi Nozaki, Yuki Tokudome, Katsuhiko Tsunoda, Kenji Urayama","doi":"10.1021/acs.macromol.5c02962","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02962","url":null,"abstract":"We investigate the coupled evolution of heterogeneous strain, crystallinity, and stress fields in natural rubber (NR) sheets containing a circular hole during uniaxial stretching, with a focus on how strain-induced crystallization (SIC) influences local stress concentration at structural discontinuities. By high-resolution digital image correlation, an empirical strain-crystallinity relationship and a hyperelasticity analysis firmly grounded in stress–strain data obtained under diverse deformation modes, we quantitatvely map the spatial distributions of strain, SIC, and stress in the extreme vicinity (≈0.2 mm) of the defect. Local strain concentration at the lateral hole edges triggers pronounced SIC, resulting in strong stiffening and a stress concentration factor (<i>K</i><sub>t</sub>*) as high as 4.5─significantly exceeding classical elastic predictions. Upon further stretching, <i>K</i><sub>t</sub>* plateaus, eventually as SIC develops in the far-field region, promoting a more homogeneous stress distribution. The SIC-induced stiffening also generates a highly anisotropic stress field near the hole edges due to preferential reinforcement along the crystalline orientation. The localized SIC causes characteristic hole-shape evolution, where the hole becomes increasingly elongated along the stretching axis compared with the fully amorphous state. These findings elucidate the fundamental interplay between SIC and local stress concentration in elastomers with structural discontinuities and provide mechanistic insights for designing defect-tolerant, high-toughness rubber materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"16 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044768","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 : 2026-01-25DOI: 10.1021/acs.macromol.5c03176
Xueqin Xi, Yaning Gao, Jinhong Jia, Hui Sun
The controlled preparation of stimulus-responsive soft nanomaterials, especially those with anisotropic nanostructures, has attracted wide attention. Herein, a series of N-(2-(6-(4-(diphenylamino)phenyl)-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)ethyl)acrylamide (TNAA, n = 0, 1, 2, 3, or 4)-containing luminescent monomers with an adjustable flexible spacer length are randomly copolymerized with N-isopropylacrylamide (NIPAM) to afford thermoresponsive polymers with a tunable cloud point temperature (CP) and fluorescence emission. By adjusting the molar ratio of TNAA to NIPAM, the CP of the polymers can be regulated from 49.1 ± 0.7 to 26.0 ± 0.8 °C, while the emission wavelength is controlled from 598 to 633 nm as the length of the flexible spacer shortens. Density functional theory calculation results verify that as the length of flexible spacers increases, the path for intramolecular electron transfer becomes longer. It induces an elevation in the energy required for electrons to transfer from the highest occupied molecular orbital to the lowest unoccupied molecular orbital, leading to the increase in the energy gap. Importantly, nanobowls with controlled diameter, opening size, and inherited thermoresponsive and tunable fluorescence properties are formed by self-assembly. As the temperature increases from below the CP of the polymer to 60 °C, the hydrophilic-to-hydrophobic transition of PNIPAM segments occurs, leading to the enhancement of the hydrophobic interactions and a more compact aggregation of the polymer chains. Consequently, the nanobowls also change from their original loose and porous structure to a relatively dense state. Overall, thermoresponsive luminescent nanobowls with controlled dimensions and fluorescence properties are achieved by manipulating the spacer length between fluorophores and the polymer backbone.
{"title":"Thermoresponsive Luminescent Nanobowls with Controlled Fluorescence Properties: The Role of a Flexible Spacer Length","authors":"Xueqin Xi, Yaning Gao, Jinhong Jia, Hui Sun","doi":"10.1021/acs.macromol.5c03176","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03176","url":null,"abstract":"The controlled preparation of stimulus-responsive soft nanomaterials, especially those with anisotropic nanostructures, has attracted wide attention. Herein, a series of <i>N</i>-(2-(6-(4-(diphenylamino)phenyl)-1,3-dioxo-1<i>H</i>-benzo[de]isoquinolin-2(3<i>H</i>)-yl)ethyl)acrylamide (TNAA, <i>n</i> = 0, 1, 2, 3, or 4)-containing luminescent monomers with an adjustable flexible spacer length are randomly copolymerized with <i>N</i>-isopropylacrylamide (NIPAM) to afford thermoresponsive polymers with a tunable cloud point temperature (CP) and fluorescence emission. By adjusting the molar ratio of TNAA to NIPAM, the CP of the polymers can be regulated from 49.1 ± 0.7 to 26.0 ± 0.8 °C, while the emission wavelength is controlled from 598 to 633 nm as the length of the flexible spacer shortens. Density functional theory calculation results verify that as the length of flexible spacers increases, the path for intramolecular electron transfer becomes longer. It induces an elevation in the energy required for electrons to transfer from the highest occupied molecular orbital to the lowest unoccupied molecular orbital, leading to the increase in the energy gap. Importantly, nanobowls with controlled diameter, opening size, and inherited thermoresponsive and tunable fluorescence properties are formed by self-assembly. As the temperature increases from below the CP of the polymer to 60 °C, the hydrophilic-to-hydrophobic transition of PNIPAM segments occurs, leading to the enhancement of the hydrophobic interactions and a more compact aggregation of the polymer chains. Consequently, the nanobowls also change from their original loose and porous structure to a relatively dense state. Overall, thermoresponsive luminescent nanobowls with controlled dimensions and fluorescence properties are achieved by manipulating the spacer length between fluorophores and the polymer backbone.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"87 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044736","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}
Owing to their biocompatibility and thermal responsiveness, Agar hydrogels are extensively applied in chemistry and biology fields. However, their fixed water content and rigid sugar ring structure normally exhibit limited mechanical strength, while introducing additional networks possibly deteriorates the intrinsic thermoreversible cross-linking properties of Agar hydrogel. In this work, we achieve the mechanical enhancement and tunability of Agar-based single-network hydrogels based on the Hofmeister effect via a preforming postimmersion method without the need for supplementary networks. After being immersed in different solutions of the Hofmeister salt series, the tensile strength and toughness of Agar hydrogels can be regulated between 54.7–412.1 kPa and 5.5–94.1 kJ m–3. Macroscopic and microscopic analyses via SEM and SAXS, together with molecular dynamics simulations, were employed to reveal the systematic mechanisms from the number of hydrogen bonds to the aggregation state and ultimately to the mechanical properties. Since the gelation of Agar relies on double-helix formation, the Hofmeister series and regulation behaviors are different from typical synthetic polymer hydrogels. These results further promoted the elucidation of the water state regulation in the hydration layer of Agar hydrogels. This work provides an understanding of the correlation between the cross-linking state of molecular chains and the resultant Agar hydrogel properties based on the Hofmeister effect, which inspires research on the mechanical regulation mechanisms of natural polysaccharide-based hydrogels.
{"title":"The Hofmeister Effect on Agar Hydrogels with Mechanical Tunability and Molecular Mechanism","authors":"Jueying Yang, Weiting Huang, Jingyu Deng, Jian Li, Shahrudin Ibrahim, Younghwan Choe, Chang Su Lim, Lijie Li, Yu Chen, Nam-Joon Cho","doi":"10.1021/acs.macromol.5c03189","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03189","url":null,"abstract":"Owing to their biocompatibility and thermal responsiveness, Agar hydrogels are extensively applied in chemistry and biology fields. However, their fixed water content and rigid sugar ring structure normally exhibit limited mechanical strength, while introducing additional networks possibly deteriorates the intrinsic thermoreversible cross-linking properties of Agar hydrogel. In this work, we achieve the mechanical enhancement and tunability of Agar-based single-network hydrogels based on the Hofmeister effect via a preforming postimmersion method without the need for supplementary networks. After being immersed in different solutions of the Hofmeister salt series, the tensile strength and toughness of Agar hydrogels can be regulated between 54.7–412.1 kPa and 5.5–94.1 kJ m<sup>–3</sup>. Macroscopic and microscopic analyses via SEM and SAXS, together with molecular dynamics simulations, were employed to reveal the systematic mechanisms from the number of hydrogen bonds to the aggregation state and ultimately to the mechanical properties. Since the gelation of Agar relies on double-helix formation, the Hofmeister series and regulation behaviors are different from typical synthetic polymer hydrogels. These results further promoted the elucidation of the water state regulation in the hydration layer of Agar hydrogels. This work provides an understanding of the correlation between the cross-linking state of molecular chains and the resultant Agar hydrogel properties based on the Hofmeister effect, which inspires research on the mechanical regulation mechanisms of natural polysaccharide-based hydrogels.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"395 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044772","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}
Confined assembly of chiral block copolymers (BCPs*) affords an effective approach to preparing controllable chiral nanostructures, yet the interplay among molecular hydrophilicity, assembled morphology, and chiroptical properties remains unclear. In this study, we reported hydrophilicity-mediated three-dimensional (3D) confined assembly of poly(2-vinylpyridine)-block-poly(L-lactide) (P2VP-b-PLLA) and P2VP-block-poly(D-lactide) (P2VP-b-PDLA) in evaporative emulsion droplets. The assembled morphology and the chiral transfer from a molecular configuration to a microphase-separated structure was found strongly dependent on the molecular mass (Mn) and the PLA volume fraction (fPLA) due to the amphiphilic feature of the P2VP block. Specifically, BCPs* with Mn ≥ 17.7 kDa and fPLA between 17 and 28% possessed relatively high hydrophobicity and formed solid spheres with an internal helical structure. In contrast, BCPs* with lower Mn and hence higher hydrophilicity gave rise to hollow assemblies lacking an evident chiral morphology. Moreover, the addition of protonic species such as H+ further enhanced the hydrophilicity of BCP* chains via the protonation of P2VP, thus modulating the assembly behavior of BCPs*. Similar manipulation could be achieved by the addition of Lewis acidic species, such as Cu2+ and Fe3+, which hydrolyzed and released H+. Chiroptical measurements revealed that the dissymmetry factor (g-factor) strongly depended on the assembled morphology: solid spheres with an internal helical structure exhibited significantly stronger circular dichroism responses than hollow morphologies. This work demonstrated hydrophilicity as a governing parameter for confined chiral assembly and chiroptical modulation and provided new insights into the development of functional chiral materials via hydrophilicity-mediated self-assembly.
{"title":"Hydrophilicity-Mediated Three-Dimensional Confined Assembly of Chiral Block Copolymers","authors":"Hao Li, Bijin Xiong, Yutong Gao, Wei Xi, Jintao Zhu, Zhihong Nie, Jiangping Xu","doi":"10.1021/acs.macromol.5c02890","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02890","url":null,"abstract":"Confined assembly of chiral block copolymers (BCPs*) affords an effective approach to preparing controllable chiral nanostructures, yet the interplay among molecular hydrophilicity, assembled morphology, and chiroptical properties remains unclear. In this study, we reported hydrophilicity-mediated three-dimensional (3D) confined assembly of poly(2-vinylpyridine)-<i>block</i>-poly(<i>L</i>-lactide) (P2VP-<i>b</i>-PLLA) and P2VP-<i>block</i>-poly(<i>D</i>-lactide) (P2VP-<i>b</i>-PDLA) in evaporative emulsion droplets. The assembled morphology and the chiral transfer from a molecular configuration to a microphase-separated structure was found strongly dependent on the molecular mass (<i>M</i><sub>n</sub>) and the PLA volume fraction (<i>f</i><sub>PLA</sub>) due to the amphiphilic feature of the P2VP block. Specifically, BCPs* with <i>M</i><sub>n</sub> ≥ 17.7 kDa and <i>f</i><sub>PLA</sub> between 17 and 28% possessed relatively high hydrophobicity and formed solid spheres with an internal helical structure. In contrast, BCPs* with lower <i>M</i><sub>n</sub> and hence higher hydrophilicity gave rise to hollow assemblies lacking an evident chiral morphology. Moreover, the addition of protonic species such as H<sup>+</sup> further enhanced the hydrophilicity of BCP* chains via the protonation of P2VP, thus modulating the assembly behavior of BCPs*. Similar manipulation could be achieved by the addition of Lewis acidic species, such as Cu<sup>2+</sup> and Fe<sup>3+</sup>, which hydrolyzed and released H<sup>+</sup>. Chiroptical measurements revealed that the dissymmetry factor (<i>g</i>-factor) strongly depended on the assembled morphology: solid spheres with an internal helical structure exhibited significantly stronger circular dichroism responses than hollow morphologies. This work demonstrated hydrophilicity as a governing parameter for confined chiral assembly and chiroptical modulation and provided new insights into the development of functional chiral materials via hydrophilicity-mediated self-assembly.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"48 17 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044770","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 : 2026-01-24DOI: 10.1021/acs.macromol.5c03411
Wenbo Zhao, Yingxiang Li, Yan Wang, Lijun Ma, Guojie Zhang, Hong Liu
Catenated “Olympic” networks of ring polymers are emerging as versatile platforms in biology-inspired materials and MOF-catenane hybrids, yet how their pore dimensions are regulated by topology remains poorly understood. Here we use coarse-grained molecular dynamics to investigate two idealized two-dimensional Olympic networks: a square-lattice (SQR) and a hexagonal-lattice (HEX) membrane of interlocked rings. We introduce a pore-size definition based on the largest rigid sphere that can pass through a lattice pore. By varying all chain bending stiffness and a topological tension of the catenated membrane, we map out the pore-size landscape and identify two competing mechanisms: conformational entropy, which favors ring compaction and larger pores, and ring rotational degrees of freedom, allow stiff rings to invade the pore cross-section and create smaller apertures. Their competition yields a bimodal pore-size distribution in the SQR network under intermediate conditions. Using Maxwell counting and topological mechanics, we show that the isostatic SQR lattice exhibits strong nearest neighbor correlations in pore size. For hypostatic HEX lattice, with additional zero modes. This structure largely suppresses such correlations. These results establish a physical picture linking catenane topology, chain mechanics, and pore size, and provide design principles for topologically engineered polymer networks with tunable porosity and dynamic gating of guest transport.
{"title":"Topological Catenation Induced Pore Size in 2D Olympic Network","authors":"Wenbo Zhao, Yingxiang Li, Yan Wang, Lijun Ma, Guojie Zhang, Hong Liu","doi":"10.1021/acs.macromol.5c03411","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03411","url":null,"abstract":"Catenated “Olympic” networks of ring polymers are emerging as versatile platforms in biology-inspired materials and MOF-catenane hybrids, yet how their pore dimensions are regulated by topology remains poorly understood. Here we use coarse-grained molecular dynamics to investigate two idealized two-dimensional Olympic networks: a square-lattice (SQR) and a hexagonal-lattice (HEX) membrane of interlocked rings. We introduce a pore-size definition based on the largest rigid sphere that can pass through a lattice pore. By varying all chain bending stiffness and a topological tension of the catenated membrane, we map out the pore-size landscape and identify two competing mechanisms: conformational entropy, which favors ring compaction and larger pores, and ring rotational degrees of freedom, allow stiff rings to invade the pore cross-section and create smaller apertures. Their competition yields a bimodal pore-size distribution in the SQR network under intermediate conditions. Using Maxwell counting and topological mechanics, we show that the isostatic SQR lattice exhibits strong nearest neighbor correlations in pore size. For hypostatic HEX lattice, with additional zero modes. This structure largely suppresses such correlations. These results establish a physical picture linking catenane topology, chain mechanics, and pore size, and provide design principles for topologically engineered polymer networks with tunable porosity and dynamic gating of guest transport.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"31 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034205","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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