Pub Date : 2026-11-02DOI: 10.1021/acs.macromol.6c01943
Lei Huang,Qiancheng Li,Tao Yang,Ruifang Cao,Qingliang Song,Weihua Li
Previous studies have shown that the thermodynamic equilibrium structure of cylinder-forming AB diblock copolymer thin films under the lateral confinement of regular triangles with neutral top and bottom surfaces is always perfectly hexagonally arranged perpendicular cylinders. However, for practical applications, a more critical question is whether these perfect hexagonal patterns can be kinetically realized within a reasonably short annealing time. In this work, we employ coarse-grained dissipative particle dynamics simulations to investigate the self-assembly of cylinder-forming diblock copolymers under regular triangular confinement, aiming to determine the size window for achieving perfect hexagonal cylindrical patterns within a given short simulation time. Our results show that when the side length of the triangle, L, is small, with no more than 7 cylinders along each side, perfect hexagonal patterns are always obtained. As L increases such that the number of cylinders per side ranges from 8 to 15, the L window for each hexagonal pattern remains wide, and defects only emerge near the boundaries between two adjacent windows, primarily due to the formation of different numbers of cylinders along different triangular sides. For even larger L, with up to 19 cylinders per side, a notable L window for perfect hexagonal patterns still persists. By mapping the single-chain diffusion time between simulation and experiment, the simulation times chosen in our work are estimated to correspond to very short annealing times in experiments. Our work demonstrates that triangular confinement can rapidly direct cylinder-forming block copolymers to self-assemble into perfectly hexagonally arranged perpendicular cylinders over a wide range of L, providing a simple strategy for the fabrication of large-scale ordered hexagonal patterns.
{"title":"Ordering Dynamics of Cylinder-Forming AB Diblock Copolymers under Triangular Confinement","authors":"Lei Huang,Qiancheng Li,Tao Yang,Ruifang Cao,Qingliang Song,Weihua Li","doi":"10.1021/acs.macromol.6c01943","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c01943","url":null,"abstract":"Previous studies have shown that the thermodynamic equilibrium structure of cylinder-forming AB diblock copolymer thin films under the lateral confinement of regular triangles with neutral top and bottom surfaces is always perfectly hexagonally arranged perpendicular cylinders. However, for practical applications, a more critical question is whether these perfect hexagonal patterns can be kinetically realized within a reasonably short annealing time. In this work, we employ coarse-grained dissipative particle dynamics simulations to investigate the self-assembly of cylinder-forming diblock copolymers under regular triangular confinement, aiming to determine the size window for achieving perfect hexagonal cylindrical patterns within a given short simulation time. Our results show that when the side length of the triangle, L, is small, with no more than 7 cylinders along each side, perfect hexagonal patterns are always obtained. As L increases such that the number of cylinders per side ranges from 8 to 15, the L window for each hexagonal pattern remains wide, and defects only emerge near the boundaries between two adjacent windows, primarily due to the formation of different numbers of cylinders along different triangular sides. For even larger L, with up to 19 cylinders per side, a notable L window for perfect hexagonal patterns still persists. By mapping the single-chain diffusion time between simulation and experiment, the simulation times chosen in our work are estimated to correspond to very short annealing times in experiments. Our work demonstrates that triangular confinement can rapidly direct cylinder-forming block copolymers to self-assemble into perfectly hexagonally arranged perpendicular cylinders over a wide range of L, providing a simple strategy for the fabrication of large-scale ordered hexagonal patterns.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"70 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149304209","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 : 2026-11-02DOI: 10.1021/acs.macromol.6c01637
Yisheng Sun,Basma Elshazly,Tara Y. Meyer
Tuning the degradation profile of resorbable polymers is a longstanding goal in materials design. Bottlebrush copolymers (BBCs) offer an additional handle, relative to linear polymers, which is the spatial arrangement of chemically distinct sidechains along a common backbone. We report that backbone sequence modulates the sidechain degradation rate in BBCs bearing poly(lactic acid) (PLA) and/or poly(lactic-co-glycolic acid) (PLGA, 50/50 L:G) sidechains. Using a grafting-through strategy with vinyl-terminated PLA and PLGA macromonomers, we prepared BBCs of matched overall composition but distinct sidechain distributions: random, alternating, gradient, and diblock. Hydrolytic degradation was tracked by 1H NMR spectroscopy, size-exclusion chromatography, and multi-angle light scattering. The architectures exhibit sequence-dependent PLA degradation rates in the order diblock < gradient < (random ≈ alternating), with random and alternating profiles indistinguishable within experimental error. This ordering is consistent with a neighboring effect wherein greater PLGA-PLA proximity accelerates PLA degradation. The finding that the random and alternating BBCs share a degradation profile despite different local adjacencies indicates that the effect is regional, set by the fraction of nearby fast-cleaving PLGA rather than by direct neighbor identity. Sidechain arrangement along the backbone is therefore a distinct handle for tuning hydrolytic degradation, alongside composition, molecular weight, stereochemistry, and microstructure.
{"title":"A Proximity-Driven Neighbor Effect in the Degradation of PLA/PLGA Bottlebrush Copolymers","authors":"Yisheng Sun,Basma Elshazly,Tara Y. Meyer","doi":"10.1021/acs.macromol.6c01637","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c01637","url":null,"abstract":"Tuning the degradation profile of resorbable polymers is a longstanding goal in materials design. Bottlebrush copolymers (BBCs) offer an additional handle, relative to linear polymers, which is the spatial arrangement of chemically distinct sidechains along a common backbone. We report that backbone sequence modulates the sidechain degradation rate in BBCs bearing poly(lactic acid) (PLA) and/or poly(lactic-co-glycolic acid) (PLGA, 50/50 L:G) sidechains. Using a grafting-through strategy with vinyl-terminated PLA and PLGA macromonomers, we prepared BBCs of matched overall composition but distinct sidechain distributions: random, alternating, gradient, and diblock. Hydrolytic degradation was tracked by 1H NMR spectroscopy, size-exclusion chromatography, and multi-angle light scattering. The architectures exhibit sequence-dependent PLA degradation rates in the order diblock < gradient < (random ≈ alternating), with random and alternating profiles indistinguishable within experimental error. This ordering is consistent with a neighboring effect wherein greater PLGA-PLA proximity accelerates PLA degradation. The finding that the random and alternating BBCs share a degradation profile despite different local adjacencies indicates that the effect is regional, set by the fraction of nearby fast-cleaving PLGA rather than by direct neighbor identity. Sidechain arrangement along the backbone is therefore a distinct handle for tuning hydrolytic degradation, alongside composition, molecular weight, stereochemistry, and microstructure.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"12 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149304189","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}
Although numerous catechol-containing adhesives have been reported, they generally suffer from the absence of real-time detection functionality, which limits their applications in intelligent manufacturing. Herein, we present a simulation-guided strategy via ring-opening metathesis polymerization (ROMP) and metal-ligand coordination to construct strong, electrically detectable catechol-containing adhesives. Initially, the homopolymer poly(3-(3,4-dihydroxy-phenyl)–2-[2-(3,5-dioxo-4-aza-tricyclo dec-8-en-4-yl)-ethoxycarbonylamino]-propionic acid methyl ester) (PDOPA200) exhibited a limited bonding strength of only 0.67 ± 0.02 MPa. To overcome this, molecular dynamics (MD) simulations were employed to investigate the influence of copolymers’ composition and structure on the bonding performance. The reactivity ratios of comonomers were determined to be 0.50 and 1.29, respectively, which suggests the formation of a gradient architecture during one-pot copolymerization. Both simulations and experiments confirmed that, compared to sequentially added block copolymers, the gradient copolymer with 40 mol % poly 4-(2-hydroxy-1-hydroxymethyl-1-methyl-ethyl)–4-aza-tricycl dec-8-ene-3,5-dione (P2OH) and a degree of polymerization of 200 achieved the highest bonding strength of 4.1 ± 0.08 MPa, which was further enhanced to 7.5 ± 0.06 MPa after complexation with Fe3+. Moreover, the obtained catechol–Fe3+ complex adhesives possess excellent solvent (acetonitrile, hexane, ethanol, acid solution, water, and artificial seawater) resistance and wide applications, especially in real-time crack/failure detection of the adhesive. The obtained catechol-containing adhesives can expand the variety of detectable adhesives and have great application prospects in intelligent manufacturing.
{"title":"Detectable Catechol-Containing Adhesives with High Performance Efficiently Prepared by ROMP and Complexation","authors":"Lifen Xiao,Jiahao Liao,yinshuang Ding,Youming Zhang,Chengxi Li,Geng Huang,Jie Li,Qingquan Tang","doi":"10.1021/acs.macromol.6c02306","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c02306","url":null,"abstract":"Although numerous catechol-containing adhesives have been reported, they generally suffer from the absence of real-time detection functionality, which limits their applications in intelligent manufacturing. Herein, we present a simulation-guided strategy via ring-opening metathesis polymerization (ROMP) and metal-ligand coordination to construct strong, electrically detectable catechol-containing adhesives. Initially, the homopolymer poly(3-(3,4-dihydroxy-phenyl)–2-[2-(3,5-dioxo-4-aza-tricyclo dec-8-en-4-yl)-ethoxycarbonylamino]-propionic acid methyl ester) (PDOPA200) exhibited a limited bonding strength of only 0.67 ± 0.02 MPa. To overcome this, molecular dynamics (MD) simulations were employed to investigate the influence of copolymers’ composition and structure on the bonding performance. The reactivity ratios of comonomers were determined to be 0.50 and 1.29, respectively, which suggests the formation of a gradient architecture during one-pot copolymerization. Both simulations and experiments confirmed that, compared to sequentially added block copolymers, the gradient copolymer with 40 mol % poly 4-(2-hydroxy-1-hydroxymethyl-1-methyl-ethyl)–4-aza-tricycl dec-8-ene-3,5-dione (P2OH) and a degree of polymerization of 200 achieved the highest bonding strength of 4.1 ± 0.08 MPa, which was further enhanced to 7.5 ± 0.06 MPa after complexation with Fe3+. Moreover, the obtained catechol–Fe3+ complex adhesives possess excellent solvent (acetonitrile, hexane, ethanol, acid solution, water, and artificial seawater) resistance and wide applications, especially in real-time crack/failure detection of the adhesive. The obtained catechol-containing adhesives can expand the variety of detectable adhesives and have great application prospects in intelligent manufacturing.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"255 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149304186","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}
Anionic polymerization of 1-cyclohexyl[3]dendralene (1CH3D) proceeded with potassium naphthalenide (K-Naph) or diphenylmethylpotassium (Ph2CHK) in tetrahydrofuran (THF) at –78 °C. Poly(1CH3D)s with the predicted molecular weights and narrow molecular weight distributions (MWD, Mw/Mn < 1.1) were quantitatively obtained. The polymerization of 1CH3D was attempted using sec-butyllithium (s-BuLi) in toluene to investigate the effect of solvent polarity. Sequential copolymerization of 1CH3D and 2-vinylpyridine was conducted using Ph2CHK to afford a poly(1CH3D)-b-poly(2-vinylpyridine) with well-defined chain structures, indicating the living character of the polymerization. Various nuclear magnetic resonance measurements revealed that the microstructure of poly(1CH3D) prepared in THF consisted of the 4,6-structure (80%) and 4,3-structure (20%). Meanwhile, the 4,6-structure content reached 94% in the polymer obtained in toluene. These results indicate that 1CH3D underwent propagation not only via conjugated addition mode but also via vinyl addition mode. The hydrogenation of poly(1CH3D) having a high 4,6-structure (>91%) was attempted to obtain an alternating copolymer, poly(ethylene-alt-1-butenylcyclohexane). The poly(1CH3D)s showed glass transition temperatures between 1 and 16 °C and a cross-linking property by heating over 270 °C.
{"title":"Living Anionic Polymerization of 1-Cyclohexyl[3]dendralene","authors":"Haruto Tanaka,Tomoyuki Toda,Katsuhiko Takenaka,Chihiro Homma,Takashi Ishizone","doi":"10.1021/acs.macromol.6c02252","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c02252","url":null,"abstract":"Anionic polymerization of 1-cyclohexyl[3]dendralene (1CH3D) proceeded with potassium naphthalenide (K-Naph) or diphenylmethylpotassium (Ph2CHK) in tetrahydrofuran (THF) at –78 °C. Poly(1CH3D)s with the predicted molecular weights and narrow molecular weight distributions (MWD, Mw/Mn < 1.1) were quantitatively obtained. The polymerization of 1CH3D was attempted using sec-butyllithium (s-BuLi) in toluene to investigate the effect of solvent polarity. Sequential copolymerization of 1CH3D and 2-vinylpyridine was conducted using Ph2CHK to afford a poly(1CH3D)-b-poly(2-vinylpyridine) with well-defined chain structures, indicating the living character of the polymerization. Various nuclear magnetic resonance measurements revealed that the microstructure of poly(1CH3D) prepared in THF consisted of the 4,6-structure (80%) and 4,3-structure (20%). Meanwhile, the 4,6-structure content reached 94% in the polymer obtained in toluene. These results indicate that 1CH3D underwent propagation not only via conjugated addition mode but also via vinyl addition mode. The hydrogenation of poly(1CH3D) having a high 4,6-structure (>91%) was attempted to obtain an alternating copolymer, poly(ethylene-alt-1-butenylcyclohexane). The poly(1CH3D)s showed glass transition temperatures between 1 and 16 °C and a cross-linking property by heating over 270 °C.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"19 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149304187","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 : 2026-10-30DOI: 10.1021/acs.macromol.6c01305
Long Chen,Zuming Wu,Ben Zhong Tang,Rongrong Hu
The exploration of phosphorus-containing polymer structures and development of their facile and efficient synthetic approaches are of great challenge and significance in polymer science. In this work, an efficient multicomponent polymerization of carbamates, chlorodiphenylphosphine, and aromatic aldehyde was developed for the facile access to a new group of phosphorus-containing polymers—poly(α-carbamatephosphineoxide)s. The polymerization went efficiently in 1,4-dioxane at 70 °C, without any catalyst or additive, producing poly(α-carbamatephosphineoxide)s with well-defined chemical structures, satisfying molecular weights (Mns up to 17,500 g/mol), and high yields (up to 91%). These poly(α-carbamatephosphineoxide)s possess abundant intermolecular hydrogen bonds, good thermal stability, and aggregation-induced emission property. The chlorophosphine-involving multicomponent polymerization could hence provide facile access to new phosphorus-containing polymer structures, promoting the advancement of phosphorus-containing polymer materials.
{"title":"Multicomponent Polymerization of Carbamates, Chlorodiphenylphosphine, and Aromatic Aldehyde toward Poly(α-carbamatephosphineoxide)s","authors":"Long Chen,Zuming Wu,Ben Zhong Tang,Rongrong Hu","doi":"10.1021/acs.macromol.6c01305","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c01305","url":null,"abstract":"The exploration of phosphorus-containing polymer structures and development of their facile and efficient synthetic approaches are of great challenge and significance in polymer science. In this work, an efficient multicomponent polymerization of carbamates, chlorodiphenylphosphine, and aromatic aldehyde was developed for the facile access to a new group of phosphorus-containing polymers—poly(α-carbamatephosphineoxide)s. The polymerization went efficiently in 1,4-dioxane at 70 °C, without any catalyst or additive, producing poly(α-carbamatephosphineoxide)s with well-defined chemical structures, satisfying molecular weights (Mns up to 17,500 g/mol), and high yields (up to 91%). These poly(α-carbamatephosphineoxide)s possess abundant intermolecular hydrogen bonds, good thermal stability, and aggregation-induced emission property. The chlorophosphine-involving multicomponent polymerization could hence provide facile access to new phosphorus-containing polymer structures, promoting the advancement of phosphorus-containing polymer materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"19 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149281873","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 : 2026-10-30DOI: 10.1021/acs.macromol.6c01309
Suyeon Kim,Taejin Kwon
Single-molecule probes are widely used to characterize dynamic heterogeneity in glass-forming liquids, but their measured dynamics can depend on how the probe couples to its host environment. Using molecular dynamics simulations of dilute dimer probes embedded in a supercooled polymer melt, we examine how probe–host affinity influences the correspondence between probe rotational relaxation and host dynamics. Increasing the probe–host interaction strength systematically modifies the relative temperature dependence of probe and host relaxation while leaving the intrinsic host dynamics essentially unperturbed. Lower-affinity probes exhibit stronger non-Gaussian translational motion and larger displacement fluctuations, whereas higher-affinity probes remain more localized and are statistically less exposed to the most dynamically active host environments. Comparison with wavevector-dependent host structural relaxation further identifies an effective matching wavevector at which the host structural relaxation exhibits the temperature dependence most similar to that of the probe, providing a phenomenological measure of the probe–host dynamical correspondence. Together with real-space analyses of the local environments sampled by the probe, these results show that probe–host affinity systematically influences the quantitative relationship between molecular-probe relaxation and heterogeneous host dynamics.
{"title":"Interaction-Dependent Molecular Probing of Heterogeneous Glassy Dynamics in Polymer Melts","authors":"Suyeon Kim,Taejin Kwon","doi":"10.1021/acs.macromol.6c01309","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c01309","url":null,"abstract":"Single-molecule probes are widely used to characterize dynamic heterogeneity in glass-forming liquids, but their measured dynamics can depend on how the probe couples to its host environment. Using molecular dynamics simulations of dilute dimer probes embedded in a supercooled polymer melt, we examine how probe–host affinity influences the correspondence between probe rotational relaxation and host dynamics. Increasing the probe–host interaction strength systematically modifies the relative temperature dependence of probe and host relaxation while leaving the intrinsic host dynamics essentially unperturbed. Lower-affinity probes exhibit stronger non-Gaussian translational motion and larger displacement fluctuations, whereas higher-affinity probes remain more localized and are statistically less exposed to the most dynamically active host environments. Comparison with wavevector-dependent host structural relaxation further identifies an effective matching wavevector at which the host structural relaxation exhibits the temperature dependence most similar to that of the probe, providing a phenomenological measure of the probe–host dynamical correspondence. Together with real-space analyses of the local environments sampled by the probe, these results show that probe–host affinity systematically influences the quantitative relationship between molecular-probe relaxation and heterogeneous host dynamics.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"31 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149304184","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 : 2026-10-30DOI: 10.1021/acs.macromol.6c02351
David T. Kennedy,Timothy J. White
Liquid crystalline elastomers (LCEs) couple liquid-crystalline order with elastomeric deformability. Their self-assembly reflects a balance between cohesive interactions among aromatic mesogenic cores and the fluidity imparted by aliphatic chains. Here, we examine the contribution of mesogen-mesogen packing to thermomechanical response by comparing LCEs prepared from nearly identical mesogens while holding spacer length, network chemistry, and stoichiometry constant. Relative to its unmethylated analogue C6Sym, the canonical methylated mesogen C6M forms a nematic LCE characterized by reduced packing coherence and a broader, lower-temperature actuation response. The correlation between mesogen-mesogen registry and actuation is further evident in LCEs prepared from isomeric smectogens C6Sym and C6Asym. Although both neat monomers form smectic phases, intermediate blends exhibit expanded mesogen spacing and reduced longitudinal coherence, losing smectic character. As with C6M, expanded lateral mesogen spacing in these blends accompanies weaker strain-temperature coupling and lower-temperature actuation. At 50% C6Sym, the temperature of maximum strain-temperature coupling is approximately 70–84 °C below those of the neat endpoints. Across both comparisons, disrupted packing and altered mesogen spacing correlate with weaker strain-temperature coupling and broader, lower-temperature actuation.
{"title":"Mesogen–Mesogen Registry Tunes Thermomechanical Actuation in Surface-Aligned Liquid Crystalline Elastomers","authors":"David T. Kennedy,Timothy J. White","doi":"10.1021/acs.macromol.6c02351","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c02351","url":null,"abstract":"Liquid crystalline elastomers (LCEs) couple liquid-crystalline order with elastomeric deformability. Their self-assembly reflects a balance between cohesive interactions among aromatic mesogenic cores and the fluidity imparted by aliphatic chains. Here, we examine the contribution of mesogen-mesogen packing to thermomechanical response by comparing LCEs prepared from nearly identical mesogens while holding spacer length, network chemistry, and stoichiometry constant. Relative to its unmethylated analogue C6Sym, the canonical methylated mesogen C6M forms a nematic LCE characterized by reduced packing coherence and a broader, lower-temperature actuation response. The correlation between mesogen-mesogen registry and actuation is further evident in LCEs prepared from isomeric smectogens C6Sym and C6Asym. Although both neat monomers form smectic phases, intermediate blends exhibit expanded mesogen spacing and reduced longitudinal coherence, losing smectic character. As with C6M, expanded lateral mesogen spacing in these blends accompanies weaker strain-temperature coupling and lower-temperature actuation. At 50% C6Sym, the temperature of maximum strain-temperature coupling is approximately 70–84 °C below those of the neat endpoints. Across both comparisons, disrupted packing and altered mesogen spacing correlate with weaker strain-temperature coupling and broader, lower-temperature actuation.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"20 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149304185","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 : 2026-10-29DOI: 10.1021/acs.macromol.6c01914
Xuchen Lyu,Kamani Sudhir K. Reddy,Tam Nguyen,Baozhong Zhang,Patric Jannasch
Poly(butylene adipate-co-terephthalate) (PBAT) is a widely used biodegradable polyester. Still, the range of applications may be further broadened by extending the property range and improving recyclability. To address this issue, we gradually exchanged the adipate and terephthalate units, respectively, of PBAT with rigid spiroacetal units. These units are incorporated by adding a biobased spiroacetal diester monomer, synthesized from glyoxylic acid, bio-pentaerythritol, and methanol, in the polycondensations. The synthesis exhibits a low environmental factor (E-factor = 0.47) with acid catalyst and methanol recycling, indicating environmental sustainability. Increasing contents of the spiroacetal units lead to increased glass transition temperatures (Tgs) and reduced crystallinity and melting points, consistent with the introduction of bulky cycloaliphatic structures into the backbone. Hence, the resulting polyesters show widely tunable Tgs (–20 to 63 °C) and viscoelastic properties while retaining the original molecular weight of PBAT. The spiroacetal units also introduce predetermined cleavage sites into the polyester backbone, which undergo selective cleavage of ester bonds adjacent to the spiroacetal units in neat methanol at room temperature, accompanied by rapid physical disintegration. Theoretical calculations reveal that the carbonyls of these ester groups are more electrophilic and have a lower barrier toward methoxide attack than the terephthalate ester groups, providing a molecular-level explanation for the observed bond selectivity. These results establish electronic differentiation between ester linkages as a molecular-design principle for programming selective deconstruction of the polyester backbones. Thus, the comonomer content controls not only the material properties but also the density of chemically programmed cleavage sites and, consequently, the degradation behavior of the polymer. The degradation products are readily recovered by filtration and are then re-polymerized. Moreover, the chemically recycled material shows an almost identical composition and performance to the virgin copolyester, demonstrating the effectiveness of the closed-loop chemical recycling.
{"title":"Introducing Spiroacetal Units to Tune Thermomechanical Properties and Enhance Chemical Recyclability of Poly(butylene adipate-co-terephthalate)","authors":"Xuchen Lyu,Kamani Sudhir K. Reddy,Tam Nguyen,Baozhong Zhang,Patric Jannasch","doi":"10.1021/acs.macromol.6c01914","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c01914","url":null,"abstract":"Poly(butylene adipate-co-terephthalate) (PBAT) is a widely used biodegradable polyester. Still, the range of applications may be further broadened by extending the property range and improving recyclability. To address this issue, we gradually exchanged the adipate and terephthalate units, respectively, of PBAT with rigid spiroacetal units. These units are incorporated by adding a biobased spiroacetal diester monomer, synthesized from glyoxylic acid, bio-pentaerythritol, and methanol, in the polycondensations. The synthesis exhibits a low environmental factor (E-factor = 0.47) with acid catalyst and methanol recycling, indicating environmental sustainability. Increasing contents of the spiroacetal units lead to increased glass transition temperatures (Tgs) and reduced crystallinity and melting points, consistent with the introduction of bulky cycloaliphatic structures into the backbone. Hence, the resulting polyesters show widely tunable Tgs (–20 to 63 °C) and viscoelastic properties while retaining the original molecular weight of PBAT. The spiroacetal units also introduce predetermined cleavage sites into the polyester backbone, which undergo selective cleavage of ester bonds adjacent to the spiroacetal units in neat methanol at room temperature, accompanied by rapid physical disintegration. Theoretical calculations reveal that the carbonyls of these ester groups are more electrophilic and have a lower barrier toward methoxide attack than the terephthalate ester groups, providing a molecular-level explanation for the observed bond selectivity. These results establish electronic differentiation between ester linkages as a molecular-design principle for programming selective deconstruction of the polyester backbones. Thus, the comonomer content controls not only the material properties but also the density of chemically programmed cleavage sites and, consequently, the degradation behavior of the polymer. The degradation products are readily recovered by filtration and are then re-polymerized. Moreover, the chemically recycled material shows an almost identical composition and performance to the virgin copolyester, demonstrating the effectiveness of the closed-loop chemical recycling.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"64 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149281938","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}
Long polymer chains are inevitably tangled in knots that compromise their mechanical strength, yet how knot complexity governs the molecular rupture mechanism remains poorly understood. Here, we study the mechanical failure of single polyethylene chains bearing knots of varying complexity (3–7 crossings) using reactive molecular dynamics simulations across multiple pulling rates. We identify a consistent three-stage failure mechanism comprising entropy-driven tightening, enthalpy-driven tightening, and bond rupture. The breaking force follows a stretched exponential decay with knot complexity, while the elastic modulus grows exponentially; topological confinement therefore plays two competing roles. Analysis of bond-breaking locations indicates a gradual crossover in the failure mechanism: knots with lower minimum crossing number (31, 41) break predominantly at the knot entrance/exit, whereas knots with higher minimum crossing number (71) rupture within the densely packed core. Bond angle analysis shows that the geometric distinction between entrance and core regions diminishes with increasing minimum crossing number, providing a structural rationale for the boundary-to-core shift and demonstrating that knot topology offers a tunable handle on both polymer strength and stiffness.
{"title":"Topology-Dependent Mechanical Failure of Knotted Polymer Chains from Reactive Molecular Dynamics","authors":"Zhirui Xiang,Tianhang Zhou,Francesco Zonta,Zhenghao Wu","doi":"10.1021/acs.macromol.6c01298","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c01298","url":null,"abstract":"Long polymer chains are inevitably tangled in knots that compromise their mechanical strength, yet how knot complexity governs the molecular rupture mechanism remains poorly understood. Here, we study the mechanical failure of single polyethylene chains bearing knots of varying complexity (3–7 crossings) using reactive molecular dynamics simulations across multiple pulling rates. We identify a consistent three-stage failure mechanism comprising entropy-driven tightening, enthalpy-driven tightening, and bond rupture. The breaking force follows a stretched exponential decay with knot complexity, while the elastic modulus grows exponentially; topological confinement therefore plays two competing roles. Analysis of bond-breaking locations indicates a gradual crossover in the failure mechanism: knots with lower minimum crossing number (31, 41) break predominantly at the knot entrance/exit, whereas knots with higher minimum crossing number (71) rupture within the densely packed core. Bond angle analysis shows that the geometric distinction between entrance and core regions diminishes with increasing minimum crossing number, providing a structural rationale for the boundary-to-core shift and demonstrating that knot topology offers a tunable handle on both polymer strength and stiffness.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"22 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149251045","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 : 2026-10-28DOI: 10.1021/acs.macromol.6c02433
Xuhong Zheng,Zhen Chen,Linghui Cui,Gaopeng Shi
Decoupling ion transport from segmental motion offers a promising route for solid polymer electrolytes, yet identifying its governing factor, whether the glass transition temperature (Tg), fragility index (m), or dynamic heterogeneity, remains challenging due to their inherent interdependence. Here, we systematically investigate this decoupling in poly(vinyl acetal)s by varying acetal group length, molecular weight, plasticization, and antiplasticization. It was found that decoupling strength is not dictated simply by Tg, m, or dynamic heterogeneity. Microstructurally, the dynamically heterogeneous “slow” domains are characterized by dense molecular packing and higher cohesive energy density, irrespective of plasticization or antiplasticization. This same characteristic is observed in poly(vinyl acetal) bearing short acetal groups, wherein a weak decoupling effect is also detectable as observed in the “slow” domains. Furthermore, a negative correlation between decoupling exponent and the square of solubility parameter (i.e., cohesive energy density) at room temperature was found, confirming that cohesive energy density plays a key role in governing decoupling. We suppose that the enhanced cohesive energy density impedes ion motion and confines it to proceed only in tandem with segmental relaxation. These findings not only provide new experimental evidence for the decoupling mechanism but also support relevant theoretical frameworks of glass formation.
{"title":"New Insights into the Decoupling Mechanism of Ion Motion from Segmental Relaxation in Glass-Forming Polymers: The Interplay of Cohesive Energy Density","authors":"Xuhong Zheng,Zhen Chen,Linghui Cui,Gaopeng Shi","doi":"10.1021/acs.macromol.6c02433","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c02433","url":null,"abstract":"Decoupling ion transport from segmental motion offers a promising route for solid polymer electrolytes, yet identifying its governing factor, whether the glass transition temperature (Tg), fragility index (m), or dynamic heterogeneity, remains challenging due to their inherent interdependence. Here, we systematically investigate this decoupling in poly(vinyl acetal)s by varying acetal group length, molecular weight, plasticization, and antiplasticization. It was found that decoupling strength is not dictated simply by Tg, m, or dynamic heterogeneity. Microstructurally, the dynamically heterogeneous “slow” domains are characterized by dense molecular packing and higher cohesive energy density, irrespective of plasticization or antiplasticization. This same characteristic is observed in poly(vinyl acetal) bearing short acetal groups, wherein a weak decoupling effect is also detectable as observed in the “slow” domains. Furthermore, a negative correlation between decoupling exponent and the square of solubility parameter (i.e., cohesive energy density) at room temperature was found, confirming that cohesive energy density plays a key role in governing decoupling. We suppose that the enhanced cohesive energy density impedes ion motion and confines it to proceed only in tandem with segmental relaxation. These findings not only provide new experimental evidence for the decoupling mechanism but also support relevant theoretical frameworks of glass formation.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"21 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149251054","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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