Pub Date : 2026-03-25DOI: 10.1021/acs.macromol.6c00091
Erin C. Krist,Fu-Sheng Wang,Michael J. A. Hore,Aleksandr V. Zhukhovitskiy
Recent work established the viability of a supramolecular template approach to control the formation of trapped entanglements in polymer networks. However, characterization of the entangled networks has been limited to swelling and rheometry. Small-angle neutron and X-ray scattering techniques (SANS and SAXS, respectively) provide complementary ways to probe the size and conformation of polymer chains within the networks. Herein, we examine gels with trapped entanglements templated by bis(phenanthroline)copper(I) complexes via SANS and SAXS and compare the results against isomeric controls without templated entanglements. When the gels are swollen in deuterium oxide (D2O), a peak is observed in all cases at ∼0.08 Å–1 in both SANS and SAXS patterns, indicative of phenanthroline aggregation into scattering clusters. Tensile testing conducted with in situ SANS measurements of all the gels─with the bis(phenanthroline)copper(I) complexes intact and with the copper removed─revealed that templated entanglements prevent stress-induced dispersion of the scattering clusters in the copper-containing gels. Thus, this work illuminates how templated entanglements impact the stress response of metallogels and demonstrates the power of scattering techniques to characterize these elusive topological features of polymer networks.
{"title":"Investigation of Templated Entanglements in Polymer Networks via Small-Angle Scattering Techniques","authors":"Erin C. Krist,Fu-Sheng Wang,Michael J. A. Hore,Aleksandr V. Zhukhovitskiy","doi":"10.1021/acs.macromol.6c00091","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c00091","url":null,"abstract":"Recent work established the viability of a supramolecular template approach to control the formation of trapped entanglements in polymer networks. However, characterization of the entangled networks has been limited to swelling and rheometry. Small-angle neutron and X-ray scattering techniques (SANS and SAXS, respectively) provide complementary ways to probe the size and conformation of polymer chains within the networks. Herein, we examine gels with trapped entanglements templated by bis(phenanthroline)copper(I) complexes via SANS and SAXS and compare the results against isomeric controls without templated entanglements. When the gels are swollen in deuterium oxide (D2O), a peak is observed in all cases at ∼0.08 Å–1 in both SANS and SAXS patterns, indicative of phenanthroline aggregation into scattering clusters. Tensile testing conducted with in situ SANS measurements of all the gels─with the bis(phenanthroline)copper(I) complexes intact and with the copper removed─revealed that templated entanglements prevent stress-induced dispersion of the scattering clusters in the copper-containing gels. Thus, this work illuminates how templated entanglements impact the stress response of metallogels and demonstrates the power of scattering techniques to characterize these elusive topological features of polymer networks.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"16 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506407","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 : 2026-03-24DOI: 10.1021/acs.macromol.5c03137
Jun Woo Park,Taehyoung Kim,Linh N. T. Ho,Kyulee Jung,Dong-Gyun Kim,Sungmin Park,Hyun Kim,Woohwa Lee,Woo-Dong Jang,Yong Seok Kim,Chang-Geun Chae
A postpolymerization N-alkylamide functionalization strategy was employed to develop vinyl-addition polynorbornene (VA-PNB) derivatives capable of interchain hydrogen-bonding interactions. Vinyl-addition poly(5-methyl-2-norbornene-gradient-methyl 5-norbornene-2-carboxylate)s (VA-P(MeNB-grad-NBE)s) with varying methyl ester contents were synthesized using a catalyst system of Pd2(dba)3/PCy3/[Ph3C]+[B(C6F5)4]−. These copolymers reacted with various alkylamines under the catalysis of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, affording vinyl-addition poly[5-methyl-2-norbornene-gradient-(methyl 5-norbornene-2-carboxylate-random-N-alkyl 5-norbornene-2-carboxamide)]s (VA-P[MeNB-grad-(NBE-r-NBRA)]s; R = H (hexyl), O (octyl), D (decyl), DD (dodecyl)). These terpolymers, along with a homopolymer (VA-PMeNB) and precursor copolymers, were subjected to a comparative analysis of their physical properties to elucidate the effects of N-alkylamide functionalization. Notably, introducing only 10 mol % N-dodecylamide side chains effectively improved both tensile strength and toughness, while resulting in only a minor decrease in the glass transition temperature. The successful formation of an adaptable network is achieved by low steric congestion and the dynamic hydrogen-bonding behavior of the N-alkylamide side chains, both of which are controlled by their content and length.
{"title":"Postpolymerization N-Alkylamide Functionalization of Vinyl-Addition Polynorbornene Derivatives for Interchain Hydrogen-Bonding Interactions","authors":"Jun Woo Park,Taehyoung Kim,Linh N. T. Ho,Kyulee Jung,Dong-Gyun Kim,Sungmin Park,Hyun Kim,Woohwa Lee,Woo-Dong Jang,Yong Seok Kim,Chang-Geun Chae","doi":"10.1021/acs.macromol.5c03137","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03137","url":null,"abstract":"A postpolymerization N-alkylamide functionalization strategy was employed to develop vinyl-addition polynorbornene (VA-PNB) derivatives capable of interchain hydrogen-bonding interactions. Vinyl-addition poly(5-methyl-2-norbornene-gradient-methyl 5-norbornene-2-carboxylate)s (VA-P(MeNB-grad-NBE)s) with varying methyl ester contents were synthesized using a catalyst system of Pd2(dba)3/PCy3/[Ph3C]+[B(C6F5)4]−. These copolymers reacted with various alkylamines under the catalysis of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, affording vinyl-addition poly[5-methyl-2-norbornene-gradient-(methyl 5-norbornene-2-carboxylate-random-N-alkyl 5-norbornene-2-carboxamide)]s (VA-P[MeNB-grad-(NBE-r-NBRA)]s; R = H (hexyl), O (octyl), D (decyl), DD (dodecyl)). These terpolymers, along with a homopolymer (VA-PMeNB) and precursor copolymers, were subjected to a comparative analysis of their physical properties to elucidate the effects of N-alkylamide functionalization. Notably, introducing only 10 mol % N-dodecylamide side chains effectively improved both tensile strength and toughness, while resulting in only a minor decrease in the glass transition temperature. The successful formation of an adaptable network is achieved by low steric congestion and the dynamic hydrogen-bonding behavior of the N-alkylamide side chains, both of which are controlled by their content and length.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"49 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506412","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 novel strategy enables efficient end-functionalization of poly(3-hexylthiophene) (P3HT) with broad functional group tolerance under mild conditions. Following Kumada–Tamao catalyst-transfer condensation polymerization, the terminal nickel complex is converted to a reactive acyl intermediate through carbon monoxide insertion, which subsequently undergoes aminocarbonylation with various amines. This method successfully introduces functional groups incompatible with conventional Grignard-based approaches, including hydroxy, ester, carbonyl, and aryl halide moieties, achieving quantitative conversion within 1–12 h at room temperature. The strategy was successfully applied to synthesize well-defined P3HT-polyethylene glycol block copolymers, as confirmed by size-exclusion chromatography. Furthermore, the effective trapping of nickel(0) species by carbon monoxide prevents undesired side reactions, enabling unprecedented selective bifunctionalization of P3HT through sequential carbonylation and Suzuki–Miyaura coupling. This carbonylation-mediated approach significantly expands the structural diversity of end-functionalized conjugated polymers and provides a versatile platform for advanced materials design.
{"title":"Carbonylation-Mediated End-Functionalization of Poly(3-hexylthiophene) with Broad Functional Group Compatibility","authors":"Naoya Kanbayashi,Shunya Kitahara,Tomoki Uchida,Taka-aki Okamura,Kiyotaka Onitsuka","doi":"10.1021/acs.macromol.6c00042","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c00042","url":null,"abstract":"A novel strategy enables efficient end-functionalization of poly(3-hexylthiophene) (P3HT) with broad functional group tolerance under mild conditions. Following Kumada–Tamao catalyst-transfer condensation polymerization, the terminal nickel complex is converted to a reactive acyl intermediate through carbon monoxide insertion, which subsequently undergoes aminocarbonylation with various amines. This method successfully introduces functional groups incompatible with conventional Grignard-based approaches, including hydroxy, ester, carbonyl, and aryl halide moieties, achieving quantitative conversion within 1–12 h at room temperature. The strategy was successfully applied to synthesize well-defined P3HT-polyethylene glycol block copolymers, as confirmed by size-exclusion chromatography. Furthermore, the effective trapping of nickel(0) species by carbon monoxide prevents undesired side reactions, enabling unprecedented selective bifunctionalization of P3HT through sequential carbonylation and Suzuki–Miyaura coupling. This carbonylation-mediated approach significantly expands the structural diversity of end-functionalized conjugated polymers and provides a versatile platform for advanced materials design.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"83 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506409","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 : 2026-03-24DOI: 10.1021/acs.macromol.5c03333
Jiarui Hu,Hui Gao,Xiaoyan Wang,Yanlong Gu,Bien Tan
Flexible hyper-cross-linked polymers (HCPs) exhibit unique dynamic properties compared to their rigid counterparts, yet their synthesis remains challenging due to the inherent reactivity limitations of long-chain cross-linkers. In this work, we address the critical gaps in the synthetic difficulty in incorporating flexibility into HCPs and poorly understood structure–property relationships in flexible HCP systems. We report a novel strategy employing highly active p-toluenesulfonate (OTs)-terminated long-chain aliphatic cross-linkers to construct flexible HCPs with tunable dynamic behavior. Comprehensive characterization revealed two distinctive phenomena: pore collapse at ambient pressure and the pressure-induced gate-opening effect, as demonstrated through nitrogen sorption and methane storage experiments (measured up to 100 bar). The flexible HCPs exhibit pressure-responsive pore expansion, transitioning from contracted or even closed states at low pressure to expanded states at elevated pressures, achieving an exceptional methane working capacity of 251 cm3 (STP) cm–3 at 273 K and 5–100 bar, surpassing most reported rigid porous polymers. This study establishes a universal design principle for flexibility control in HCPs through OTs-based cross-linker length variation based on various building blocks and provides fundamental insights into dynamic structure–property relationships, paving the way for advanced applications of stimuli-responsive porous polymers.
{"title":"Flexible Hyper-Cross-Linked Polymers Knitted by OTs-Based Cross-Linkers and Their Pressure-Induced Gate-Opening Methane Adsorption","authors":"Jiarui Hu,Hui Gao,Xiaoyan Wang,Yanlong Gu,Bien Tan","doi":"10.1021/acs.macromol.5c03333","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03333","url":null,"abstract":"Flexible hyper-cross-linked polymers (HCPs) exhibit unique dynamic properties compared to their rigid counterparts, yet their synthesis remains challenging due to the inherent reactivity limitations of long-chain cross-linkers. In this work, we address the critical gaps in the synthetic difficulty in incorporating flexibility into HCPs and poorly understood structure–property relationships in flexible HCP systems. We report a novel strategy employing highly active p-toluenesulfonate (OTs)-terminated long-chain aliphatic cross-linkers to construct flexible HCPs with tunable dynamic behavior. Comprehensive characterization revealed two distinctive phenomena: pore collapse at ambient pressure and the pressure-induced gate-opening effect, as demonstrated through nitrogen sorption and methane storage experiments (measured up to 100 bar). The flexible HCPs exhibit pressure-responsive pore expansion, transitioning from contracted or even closed states at low pressure to expanded states at elevated pressures, achieving an exceptional methane working capacity of 251 cm3 (STP) cm–3 at 273 K and 5–100 bar, surpassing most reported rigid porous polymers. This study establishes a universal design principle for flexibility control in HCPs through OTs-based cross-linker length variation based on various building blocks and provides fundamental insights into dynamic structure–property relationships, paving the way for advanced applications of stimuli-responsive porous polymers.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"31 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506411","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 : 2026-03-24DOI: 10.1021/acs.macromol.5c03393
Johann L. Rapp,Eric P. Weeda,Ryan Sayko,Nick Legaux,Foad Vashahi,Sergei S. Sheiko,Andrey V. Dobrynin,Frank A. Leibfarth
Molar mass directly governs polymer properties, yet its routine measurement remains slow, offline, and largely confined to dilute solution conditions. This limitation restricts the rapid structure–property mapping needed for data-driven materials discovery and emerging self-driving laboratory workflows. Here we integrate semidilute polymer solution theory with practical in-line measurement to enable rapid determination of polymer weight-average molar mass (Mw) at concentrations typical of polymerization and processing (i.e., above the overlap concentration, c*). Building on modern scaling concepts that treat semidilute solutions as strings of correlation blobs, we establish a quantitative calibration linking solution specific viscosity to Mw for a concentration range c > c*. This framework allows Mw to be determined for unknown samples using a conventional rheometer in as little as 2 min. We implemented the same viscosity to Mw calibration under continuous flow by converting real-time pressure drop in a tubular module into solution viscosity and hence Mw. Together, the theory-grounded calibration and its flow-compatible implementation provide a practical route to rapid, Mw readout in a semidilute solution regime, enabling high-throughput synthesis and characterization workflows for materials development.
{"title":"In-Line Molar Mass Determination in Semidilute Polymer Solutions","authors":"Johann L. Rapp,Eric P. Weeda,Ryan Sayko,Nick Legaux,Foad Vashahi,Sergei S. Sheiko,Andrey V. Dobrynin,Frank A. Leibfarth","doi":"10.1021/acs.macromol.5c03393","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03393","url":null,"abstract":"Molar mass directly governs polymer properties, yet its routine measurement remains slow, offline, and largely confined to dilute solution conditions. This limitation restricts the rapid structure–property mapping needed for data-driven materials discovery and emerging self-driving laboratory workflows. Here we integrate semidilute polymer solution theory with practical in-line measurement to enable rapid determination of polymer weight-average molar mass (Mw) at concentrations typical of polymerization and processing (i.e., above the overlap concentration, c*). Building on modern scaling concepts that treat semidilute solutions as strings of correlation blobs, we establish a quantitative calibration linking solution specific viscosity to Mw for a concentration range c > c*. This framework allows Mw to be determined for unknown samples using a conventional rheometer in as little as 2 min. We implemented the same viscosity to Mw calibration under continuous flow by converting real-time pressure drop in a tubular module into solution viscosity and hence Mw. Together, the theory-grounded calibration and its flow-compatible implementation provide a practical route to rapid, Mw readout in a semidilute solution regime, enabling high-throughput synthesis and characterization workflows for materials development.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"20 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506410","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 : 2026-03-23DOI: 10.1021/acs.macromol.6c00013
Yue-Tong Dong,Jack F. Douglas,Wen-Sheng Xu
We present a molecular dynamics study of the influence of knot complexity and molecular mass on glass formation upon cooling in knotted ring polymer melts. We find that cooperative motion, rigidity, and glassy dynamics can be tuned over a wide range by knots. By leveraging these knotting constraints, we assess the validity of prevalent models of glass formation, including the string model based on the extent of cooperative particle motion, the localization model emphasizing fluctuations in local particle mobility, and the shoving model derived from emergent elastic properties in relation to the material stiffness. In line with our previous findings on polymeric and other glass-forming liquids, we demonstrate that all of these models of glass formation provide a quantitative description of segmental relaxation as a function of knot complexity, molecular mass, and temperature, despite their apparently distinct conceptual foundations. Our study thus provides additional evidence for an underlying unity among various theoretical frameworks of glass formation and for the presence of quantitative relations between the characteristic properties emphasized by these models. Furthermore, we discuss dynamic and elastic heterogeneities in relation to fragility and stiffness variations of knotted ring polymer melts, with a focus on how these trends relate to other glass-forming liquids, where fragility is tuned over a large range.
{"title":"Tunable Cooperative Motion, Rigidity, and Glassy Dynamics in Knotted Ring Polymer Melts","authors":"Yue-Tong Dong,Jack F. Douglas,Wen-Sheng Xu","doi":"10.1021/acs.macromol.6c00013","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c00013","url":null,"abstract":"We present a molecular dynamics study of the influence of knot complexity and molecular mass on glass formation upon cooling in knotted ring polymer melts. We find that cooperative motion, rigidity, and glassy dynamics can be tuned over a wide range by knots. By leveraging these knotting constraints, we assess the validity of prevalent models of glass formation, including the string model based on the extent of cooperative particle motion, the localization model emphasizing fluctuations in local particle mobility, and the shoving model derived from emergent elastic properties in relation to the material stiffness. In line with our previous findings on polymeric and other glass-forming liquids, we demonstrate that all of these models of glass formation provide a quantitative description of segmental relaxation as a function of knot complexity, molecular mass, and temperature, despite their apparently distinct conceptual foundations. Our study thus provides additional evidence for an underlying unity among various theoretical frameworks of glass formation and for the presence of quantitative relations between the characteristic properties emphasized by these models. Furthermore, we discuss dynamic and elastic heterogeneities in relation to fragility and stiffness variations of knotted ring polymer melts, with a focus on how these trends relate to other glass-forming liquids, where fragility is tuned over a large range.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"219 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506413","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}
High-density polyethylene’s (HDPE) chemical inertness, the foundation of its commercial success, renders it nearly impossible to chemically recycle. Furthermore, strict purity requirements limit mechanical recycling rates to ∼30% despite the legislative targets being 75%. Chemically recyclable polyolefin mimics containing cleavable ester linkages offer a solution, but their compatibility with commodity polyethylene waste streams remains unexplored, raising concerns that contamination could worsen rather than solve the global recycling crisis. Here, we demonstrate that HDPE-like polyesters (HDPE-like) exhibit complete miscibility with HDPE across all compositions (20–80 wt %), a crucial result given the expected difficulty to separate the HDPE-like from HDPE waste streams. Single melting transitions, cocrystallized lamellar structures, and retention of ductility confirm molecular-level mixing without mechanical failure. Strikingly, incorporation of just 20 wt %HDPE-like increases adhesion to aluminum by more than 10-fold (from 0.4 to 4.4 MPa), an effect that persists in postconsumer recycled HDPE, enabling upcycling of low-value waste into metal-laminate applications. Both components retain their recycling pathways: HDPE undergoes mechanical reprocessing, while HDPE-like achieves quantitative methanolysis to monomers that repolymerize with full property retention. By demonstrating that chemically recyclable polyesters can be miscible with, and functionally beneficial to, commodity polyolefins, this work establishes a dual-recycling framework where a contamination becomes a useful additive.
{"title":"Chemically Recyclable Polyester Miscible with HDPE Transforms Contamination into Functional Enhancement","authors":"Weronika Nowicka,Wojciech Szot,Artur Rozanski,Lanti Yang,Pankaj S. Gautam,Siva Chinta,Nikhil Verghese,Rob Duchateau,Lidia Jasinska-Walc","doi":"10.1021/acs.macromol.6c00488","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c00488","url":null,"abstract":"High-density polyethylene’s (HDPE) chemical inertness, the foundation of its commercial success, renders it nearly impossible to chemically recycle. Furthermore, strict purity requirements limit mechanical recycling rates to ∼30% despite the legislative targets being 75%. Chemically recyclable polyolefin mimics containing cleavable ester linkages offer a solution, but their compatibility with commodity polyethylene waste streams remains unexplored, raising concerns that contamination could worsen rather than solve the global recycling crisis. Here, we demonstrate that HDPE-like polyesters (HDPE-like) exhibit complete miscibility with HDPE across all compositions (20–80 wt %), a crucial result given the expected difficulty to separate the HDPE-like from HDPE waste streams. Single melting transitions, cocrystallized lamellar structures, and retention of ductility confirm molecular-level mixing without mechanical failure. Strikingly, incorporation of just 20 wt %HDPE-like increases adhesion to aluminum by more than 10-fold (from 0.4 to 4.4 MPa), an effect that persists in postconsumer recycled HDPE, enabling upcycling of low-value waste into metal-laminate applications. Both components retain their recycling pathways: HDPE undergoes mechanical reprocessing, while HDPE-like achieves quantitative methanolysis to monomers that repolymerize with full property retention. By demonstrating that chemically recyclable polyesters can be miscible with, and functionally beneficial to, commodity polyolefins, this work establishes a dual-recycling framework where a contamination becomes a useful additive.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"3 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506414","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}
To clarify the structural changes behind the viscoelastic build-up during fast free-radical polymerization, the photopolymerization of isobornyl acrylate (IBoA) was studied in detail from a synchronized viscoelastic-conversion perspective using time-resolved FT-MIR photorheology. Before effective elasticity development, polymerization proceeds in a viscous fluid state where the polymerization rate reaches a steady value after a steep ramp within the first 10% of conversion irrespective of the initiation conditions. For soft to moderate initiation the (semi)dilute entangled polymer regime before vitrification covers the second major conversion range after elasticity sets in. Interestingly, extrapolation to full conversion of the latter regime provides an alternative means to estimate the equilibrium plateau modulus and molar mass between entanglement for the bulk IBoA polymer. Further up the conversion path vitrification takes over as characterized by a steep modulus increase of at least 3 orders of magnitude over a small conversion window. Additionally, the acceleration and deceleration processes of the polymerization are discussed along the viscoelastic-conversion path.
{"title":"Viscoelastic-Conversion Scaling of the Free Radical Photopolymerization of Isobornyl Acrylate","authors":"Patrice Roose, Matthieu Roose, Jean-François Gohy, Benoit Loppinet","doi":"10.1021/acs.macromol.6c00028","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c00028","url":null,"abstract":"To clarify the structural changes behind the viscoelastic build-up during fast free-radical polymerization, the photopolymerization of isobornyl acrylate (IBoA) was studied in detail from a synchronized viscoelastic-conversion perspective using time-resolved FT-MIR photorheology. Before effective elasticity development, polymerization proceeds in a viscous fluid state where the polymerization rate reaches a steady value after a steep ramp within the first 10% of conversion irrespective of the initiation conditions. For soft to moderate initiation the (semi)dilute entangled polymer regime before vitrification covers the second major conversion range after elasticity sets in. Interestingly, extrapolation to full conversion of the latter regime provides an alternative means to estimate the equilibrium plateau modulus and molar mass between entanglement for the bulk IBoA polymer. Further up the conversion path vitrification takes over as characterized by a steep modulus increase of at least 3 orders of magnitude over a small conversion window. Additionally, the acceleration and deceleration processes of the polymerization are discussed along the viscoelastic-conversion path.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"22 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147496512","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 : 2026-03-23DOI: 10.1021/acs.macromol.5c03638
Jiayi Chen, Javier A. Vargas, Audrey Laventure
Materials with dynamic responses are pivotal for advances in soft robotics, flexible electronics, and additive manufacturing. Liquid crystal elastomers (LCEs) are especially promising due to their reversible shape changes and anisotropic mechanical properties, which depend on the molecular alignment induced during their processing and their capability to retain it afterward. While techniques such as hot-melt extrusion (HME) in 3D printing have been used to induce shear alignment of liquid crystalline domains, current approaches to reproduce, capture and characterize in real-time the evolution of this behavior are scarce. Here, we use a RM82-based oligomer liquid crystal photopolymerizable ink (LC ink) as a model system to monitor simultaneously the evolution of its order parameter ⟨P2⟩ and its rheological properties employing a rheo-IR equipment that integrates a strain-controlled rheometer with polarized attenuated total reflection infrared spectroscopy to reproduce the conditions experienced by the LC ink upon its HME. To preserve the shear-induced alignment in the RM82-based LC ink, a photopolymerization step is applied during HME, and a polarized photo-rheo-IR setup is employed to mimic the irradiation process upon extrusion. These experiments bridge the molecular and macroscopic scale, enabling us to gain valuable insights on the behavior of the LC ink upon its extrusion. This integrated approach provides direct, time-resolved insight into the interplay between processing conditions and resulting microstructure and properties, offering a promising pathway for rational processing guidelines to modulate and optimize the LCE performance, notably in actuators and soft robotics.
{"title":"Real-Time Polarized Photo-Rheo-IR Investigation of Shear-Induced Alignment in Liquid Crystal Elastomers","authors":"Jiayi Chen, Javier A. Vargas, Audrey Laventure","doi":"10.1021/acs.macromol.5c03638","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03638","url":null,"abstract":"Materials with dynamic responses are pivotal for advances in soft robotics, flexible electronics, and additive manufacturing. Liquid crystal elastomers (LCEs) are especially promising due to their reversible shape changes and anisotropic mechanical properties, which depend on the molecular alignment induced during their processing and their capability to retain it afterward. While techniques such as hot-melt extrusion (HME) in 3D printing have been used to induce shear alignment of liquid crystalline domains, current approaches to reproduce, capture and characterize in real-time the evolution of this behavior are scarce. Here, we use a RM82-based oligomer liquid crystal photopolymerizable ink (LC ink) as a model system to monitor simultaneously the evolution of its order parameter ⟨<i>P</i><sub>2</sub>⟩ and its rheological properties employing a rheo-IR equipment that integrates a strain-controlled rheometer with polarized attenuated total reflection infrared spectroscopy to reproduce the conditions experienced by the LC ink upon its HME. To preserve the shear-induced alignment in the RM82-based LC ink, a photopolymerization step is applied during HME, and a polarized photo-rheo-IR setup is employed to mimic the irradiation process upon extrusion. These experiments bridge the molecular and macroscopic scale, enabling us to gain valuable insights on the behavior of the LC ink upon its extrusion. This integrated approach provides direct, time-resolved insight into the interplay between processing conditions and resulting microstructure and properties, offering a promising pathway for rational processing guidelines to modulate and optimize the LCE performance, notably in actuators and soft robotics.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"14 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147496509","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 : 2026-03-23DOI: 10.1021/acs.macromol.5c03200
Zekun Lv, Yufei Liu, Mingfu Yu, Shaokun Yang, Tongkui Yue, Siqi Zhan, Liqun Zhang, Hengheng Zhao, Jun Liu
Enhancing polymer performance through nanocomposite strategies has emerged as an effective approach to achieve superior mechanical strength. We systematically investigated the mechanical reinforcement mechanisms of polymer composites containing ring-grafted chain nanoparticles (RGCPs) using molecular dynamics simulations. The effects of the grafted-chain assembly fraction φasse, polymer matrix chain stiffness k, and interfacial interaction strength εnp on stress transfer, entanglement formation, and overall mechanical performance were examined. Moderately short ring-grafted chains (φasse = 0.25) form a dense network of entanglements, resulting in the highest yield strength and optimal stress transfer at low to moderate strains. At high strains, however, extensive disentanglement of these entanglements causes the stress to fall below that of the φasse = 0.50 system. A matrix chain stiffness of k = 60ε/σ2 ensures sufficient chain penetrability while maintaining stable entangled structures, yielding the optimal mechanical performance. Interfacial interactions exhibit strain-dependent effects: a moderate increase in εnp promotes effective contact between grafted chains and polymers, enhancing entanglement and mechanical properties, whereas excessively strong attractive interactions cause the matrix chains to aggregate on the surfaces of the grafted rings, thereby suppressing their penetration and entanglement. Comparison with linear-grafted (LGCPs) and free-ring (RCPs) systems reveals that, relative to linear polymers with free ends, the closed-loop topology of ring-grafted chains uniquely facilitates entangled structures and improves material strength and toughness, although these entanglements are more prone to disentanglement under cyclic tensile loading. Furthermore, clustered nanoparticles reduce the mobility of ring-grafted chains, limiting their entanglement with the matrix chains. This work provides a microscopic understanding of the complex interplay among polymer conformation, entanglements, and chain dynamics in mechanical reinforcement, offering theoretical guidance for the design of high-strength and durable polymer composites.
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