Pub Date : 2024-11-13DOI: 10.1021/acs.macromol.4c02386
Mustafa H. Ahmed, Jinhyo Hwang, Bufan Xiao, Matthew R. Schiavone, Jagrity Chaudhary, Min Chen, Jianguo Mei
n-Doped poly(benzodifurandione) (n-PBDF) is an n-type conducting polymer with characteristics such as high electrical conductivity, solution processability, and weathering stability. Here, we systematically investigate the structure property relationship on the impact of structural modifications through aromatic substitution on the photophysical, electrical, and structural properties of n-PBDF and its oligomeric derivatives. We demonstrated that an electron donation group (methyl) raised the highest occupied molecular orbital energy level (+0.15 eV), while electron-withdrawing halogens (Br and Cl) decreased the lowest unoccupied molecular orbital energy level (−0.12 and −0.13 eV, respectively) in the polymers. Additionally, in both the undoped and doped oligomeric systems, these substitutions introduce large torsion angles (θ > 17°), causing the material to twist significantly. Moreover, the methyl-substituted polymer, n-PBDF-Me, was evaluated for its potential as a transparent organic conductor, due to its high optical transmittance (T550 > 93%). However, n-PBDF-Me films have significantly lower conductivity than n-PBDF (0.40 vs 1330 S/cm) at similar thickness.
n 掺杂聚（苯并二呋喃二酮）（n-PBDF）是一种 n 型导电聚合物，具有高导电性、溶液加工性和耐候稳定性等特点。在此，我们系统地研究了通过芳香族取代进行结构修饰对 n-PBDF 及其低聚衍生物的光物理、电学和结构特性的影响。我们发现，电子捐献基团（甲基）提高了聚合物的最高占有分子轨道能级（+0.15 eV），而电子抽离卤素（溴和氯）则降低了聚合物的最低未占有分子轨道能级（分别为-0.12 和-0.13 eV）。此外，在未掺杂和掺杂的低聚物体系中，这些取代物引入了较大的扭转角（θ >17°），导致材料明显扭曲。此外，由于甲基取代聚合物 n-PBDF-Me 具有很高的透光率（T550 >93%），因此对其作为透明有机导体的潜力进行了评估。然而，在厚度相似的情况下，n-PBDF-Me 薄膜的导电率明显低于 n-PBDF（0.40 vs 1330 S/cm）。
{"title":"Synthesis and Characterization of n-Doped Poly(benzodifurandione) (n-PBDF) Derivatives via Aromatic Substitution","authors":"Mustafa H. Ahmed, Jinhyo Hwang, Bufan Xiao, Matthew R. Schiavone, Jagrity Chaudhary, Min Chen, Jianguo Mei","doi":"10.1021/acs.macromol.4c02386","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02386","url":null,"abstract":"n-Doped poly(benzodifurandione) (<b>n-PBDF</b>) is an n-type conducting polymer with characteristics such as high electrical conductivity, solution processability, and weathering stability. Here, we systematically investigate the structure property relationship on the impact of structural modifications through aromatic substitution on the photophysical, electrical, and structural properties of <b>n-PBDF</b> and its oligomeric derivatives. We demonstrated that an electron donation group (methyl) raised the highest occupied molecular orbital energy level (+0.15 eV), while electron-withdrawing halogens (Br and Cl) decreased the lowest unoccupied molecular orbital energy level (−0.12 and −0.13 eV, respectively) in the polymers. Additionally, in both the undoped and doped oligomeric systems, these substitutions introduce large torsion angles (θ > 17°), causing the material to twist significantly. Moreover, the methyl-substituted polymer, <b>n-PBDF-Me</b>, was evaluated for its potential as a transparent organic conductor, due to its high optical transmittance (<i>T</i><sub>550</sub> > 93%). However, <b>n-PBDF-Me</b> films have significantly lower conductivity than <b>n-PBDF</b> (0.40 vs 1330 S/cm) at similar thickness.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"16 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601586","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 : 2024-11-12DOI: 10.1021/acs.macromol.4c01464
Yiming Chen, Jie Jiang, Yue Zhao
Combining a liquid crystal elastomer (LCE) and a hydrogel opens a new avenue for the development of materials for soft actuators. Herein, we report a novel liquid crystalline hydrogel (LCH) consisting of a cross-linked main-chain LC polyester as the LCE and cross-linked poly(vinyl alcohol) (PVA) as the hydrogel, whose actuator, in contrast to existing main-chain LCE actuators, features perpendicular alignment of LC mesogens with respect to the stretching direction and exhibits positive thermal expansion in the stretching direction over the LC–isotropic phase transition. This peculiar actuating behavior arises from a reorientation process of mesogens, switching from parallel alignment right after stretching to perpendicular alignment after thermal equilibrium of the LCH in hot water followed by cooling, which appears to occur due to a rearrangement of the LCE domains during the thermal relaxation as well as the anisotropic swelling of the surrounding hydrogel domains and thus is unique to the LCH actuator. Unlike the hydrogel actuator, whose deformation is mostly based on a water-diffusion-induced volume change and thus is generally slow, the LCH actuator is driven by the order–disorder phase transition of mesogens and is much faster, with an actuation rate in seconds. Moreover, the LCH actuator not only brings together the reversible actuation of the LCE and the water-controlled shape memory effect of the PVA hydrogel but also is capable of optical welding, which facilitates the actuator design and fabrication.
{"title":"Liquid Crystalline Hydrogel Actuator with Positive Thermal Expansion over Order–Disorder Phase Transition","authors":"Yiming Chen, Jie Jiang, Yue Zhao","doi":"10.1021/acs.macromol.4c01464","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01464","url":null,"abstract":"Combining a liquid crystal elastomer (LCE) and a hydrogel opens a new avenue for the development of materials for soft actuators. Herein, we report a novel liquid crystalline hydrogel (LCH) consisting of a cross-linked main-chain LC polyester as the LCE and cross-linked poly(vinyl alcohol) (PVA) as the hydrogel, whose actuator, in contrast to existing main-chain LCE actuators, features perpendicular alignment of LC mesogens with respect to the stretching direction and exhibits positive thermal expansion in the stretching direction over the LC–isotropic phase transition. This peculiar actuating behavior arises from a reorientation process of mesogens, switching from parallel alignment right after stretching to perpendicular alignment after thermal equilibrium of the LCH in hot water followed by cooling, which appears to occur due to a rearrangement of the LCE domains during the thermal relaxation as well as the anisotropic swelling of the surrounding hydrogel domains and thus is unique to the LCH actuator. Unlike the hydrogel actuator, whose deformation is mostly based on a water-diffusion-induced volume change and thus is generally slow, the LCH actuator is driven by the order–disorder phase transition of mesogens and is much faster, with an actuation rate in seconds. Moreover, the LCH actuator not only brings together the reversible actuation of the LCE and the water-controlled shape memory effect of the PVA hydrogel but also is capable of optical welding, which facilitates the actuator design and fabrication.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"95 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601588","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 : 2024-11-12DOI: 10.1021/acs.macromol.4c01358
Vaishaly Duhan, Bimlesh Lochab
Natural abundant resources and safe chemicals are attractive feedstocks for achieving circular sustainability. A wide variety of biophenols and greener amines offered interesting avenues in the evolution of the upcoming class of phenolic thermosets, polybenzoxazines (PBZ). High dependence on formalin as a starting material for monomer synthesis has prompted exploration of alternative safe chemicals. In this study, we designed a family of glyoxal-based benzoxazine (BZ) monomers to synthesize formaldehyde-free biothermosets, leveraging a proximity and promiscuity oxazine–oxazine dependent polymerization. The bi-oxazine functionality at the reactive C2 center in the monomers demanded significantly low temperature for ring-opening polymerization with high polymerization enthalpy favoring an ease in polymer growth, overcoming challenges posed by earlier generation BZ monomers. Current work demonstrates the proof-of-concept for a highly efficient methodology for formaldehyde replacement in benzoxazine chemistry and holds promise for the exploration of a new platform chemical, glyoxal, toward the next generation of benzoxazine with unique reactivities.
{"title":"Glyoxal-Based Bi-Oxazine Benzoxazines: Formaldehyde-Free Biothermosets","authors":"Vaishaly Duhan, Bimlesh Lochab","doi":"10.1021/acs.macromol.4c01358","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01358","url":null,"abstract":"Natural abundant resources and safe chemicals are attractive feedstocks for achieving circular sustainability. A wide variety of biophenols and greener amines offered interesting avenues in the evolution of the upcoming class of phenolic thermosets, polybenzoxazines (PBZ). High dependence on formalin as a starting material for monomer synthesis has prompted exploration of alternative safe chemicals. In this study, we designed a family of glyoxal-based benzoxazine (BZ) monomers to synthesize formaldehyde-free biothermosets, leveraging a proximity and promiscuity oxazine–oxazine dependent polymerization. The bi-oxazine functionality at the reactive C<sub>2</sub> center in the monomers demanded significantly low temperature for ring-opening polymerization with high polymerization enthalpy favoring an ease in polymer growth, overcoming challenges posed by earlier generation BZ monomers. Current work demonstrates the proof-of-concept for a highly efficient methodology for formaldehyde replacement in benzoxazine chemistry and holds promise for the exploration of a new platform chemical, glyoxal, toward the next generation of benzoxazine with unique reactivities.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"2 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599587","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 : 2024-11-12DOI: 10.1021/acs.macromol.4c02034
Joshua Lequieu
Particle and field-theoretic simulations are both commonly used methods to study the equilibrium properties of polymeric materials. Yet despite the formal equivalence of the two methods, no comprehensive comparisons of particle and field-theoretic simulations exist in the literature. In this work, we seek to fill this gap by performing a systematic and quantitative comparison of particle and field-theoretic simulations. In our comparison, we consider four representative polymeric systems: a homopolymer melt/solution, a diblock copolymer melt, a polyampholyte solution, and a polyelectrolyte gel. For each of these systems, we first demonstrate that particle and field-theoretic simulations are equivalent and yield exactly the same results for the pressure and the chemical potential. We next quantify the performance of each method across a range of different conditions including variations in chain length, system density, interaction strength, system size, and polymer volume fraction. The outcome of these calculations is a comprehensive look into the performance of each method and the systems and conditions when either particle or field-theoretic simulations are preferred. We find that field-theoretic simulations are equal to or faster than particle simulations for nearly all of the systems and conditions examined. In many situations, field-theoretic simulations are several orders of magnitude faster than particle simulations, especially if the polymer chains are long, the system density is high, and long-range Coulombic interactions are present. We also demonstrate that field-theoretic simulations are considerably faster at calculating the chemical potential and bypass the challenges associated with particle-based Widom insertion techniques. Taken together, our results provide quantitative evidence that field-theoretic simulations can reach and sample equilibrium considerably faster than particle simulations while simultaneously producing equivalent results.
{"title":"Quantitative Equivalence and Performance Comparison of Particle and Field-Theoretic Simulations","authors":"Joshua Lequieu","doi":"10.1021/acs.macromol.4c02034","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02034","url":null,"abstract":"Particle and field-theoretic simulations are both commonly used methods to study the equilibrium properties of polymeric materials. Yet despite the formal equivalence of the two methods, no comprehensive comparisons of particle and field-theoretic simulations exist in the literature. In this work, we seek to fill this gap by performing a systematic and quantitative comparison of particle and field-theoretic simulations. In our comparison, we consider four representative polymeric systems: a homopolymer melt/solution, a diblock copolymer melt, a polyampholyte solution, and a polyelectrolyte gel. For each of these systems, we first demonstrate that particle and field-theoretic simulations are equivalent and yield exactly the same results for the pressure and the chemical potential. We next quantify the performance of each method across a range of different conditions including variations in chain length, system density, interaction strength, system size, and polymer volume fraction. The outcome of these calculations is a comprehensive look into the performance of each method and the systems and conditions when either particle or field-theoretic simulations are preferred. We find that field-theoretic simulations are equal to or faster than particle simulations for nearly all of the systems and conditions examined. In many situations, field-theoretic simulations are several orders of magnitude faster than particle simulations, especially if the polymer chains are long, the system density is high, and long-range Coulombic interactions are present. We also demonstrate that field-theoretic simulations are considerably faster at calculating the chemical potential and bypass the challenges associated with particle-based Widom insertion techniques. Taken together, our results provide quantitative evidence that field-theoretic simulations can reach and sample equilibrium considerably faster than particle simulations while simultaneously producing equivalent results.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"23 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599588","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 : 2024-11-12DOI: 10.1021/acs.macromol.4c01000
Reima A. Terho, Tuomo P. Kainulainen, Mikko Aleksi Salonen, Juho Antti Sirviö, Juha P. Heiskanen
The increasing interest in reducing the dependence on fossil-based resources by searching and replacing them with renewable biobased sources has intensified in both industrial and academic sectors. Especially, lignocellulose-based biomass can be utilized in the production of many aromatic platform chemicals suitable as substitutes for known fossil-based chemicals. For example, cellulose-derived 5-(hydroxymethyl)furfural has been utilized successfully for the aforementioned purposes. On the other hand, hemicellulose-derived furfural has received rather minor attention, even though recent studies show various excellent results in applications especially utilizing furfural. In this work, two novel furfural-derived epoxy resins were synthesized. Comparative studies were conducted with commercially available and widely used fossil-based epoxy resin, diglycidyl ether of bisphenol A. Resins were cured with methylhexahydrophthalic anhydride with optimized amounts of the 2-ethyl-4-methylimidazole initiator. Curing behaviors were studied with differential scanning calorimetry while thermomechanical properties were evaluated using dynamic mechanical analysis and thermal stabilities with thermogravimetric analysis. Adhesion strengths were tested with single-lap joint steel plate samples using a tensile tester. Tensile testing was also carried out for dog-bone-shaped resin specimens. Lastly, the water absorptions were evaluated through immersion in water. Results showed that the synthesized bioresins have great potential to replace diglycidyl ether of bisphenol A in various applications.
工业界和学术界对通过寻找和使用可再生生物资源来减少对化石资源的依赖越来越感兴趣。特别是，以木质纤维素为基础的生物质可用于生产许多芳香族平台化学品，适合作为已知化石基化学品的替代品。例如，纤维素衍生的 5-（羟甲基）糠醛已成功用于上述目的。另一方面，半纤维素衍生的糠醛却很少受到关注，尽管最近的研究表明，特别是在利用糠醛的应用方面取得了各种优异的成果。本研究合成了两种新型糠醛衍生环氧树脂。树脂用甲基六氢邻苯二甲酸酐和优化量的 2-乙基-4-甲基咪唑引发剂固化。使用差示扫描量热法研究了固化行为，使用动态机械分析评估了热机械性能，使用热重分析评估了热稳定性。使用拉伸试验机测试了单搭接钢板样品的粘合强度。还对狗骨形树脂试样进行了拉伸测试。最后，通过浸泡在水中对吸水性进行了评估。结果表明，合成的生物树脂具有在各种应用中替代双酚 A 二缩水甘油醚的巨大潜力。
{"title":"Renewable Furfural-Based Sulfur-Bridged Epoxy Resins with Excellent Adhesive Properties","authors":"Reima A. Terho, Tuomo P. Kainulainen, Mikko Aleksi Salonen, Juho Antti Sirviö, Juha P. Heiskanen","doi":"10.1021/acs.macromol.4c01000","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01000","url":null,"abstract":"The increasing interest in reducing the dependence on fossil-based resources by searching and replacing them with renewable biobased sources has intensified in both industrial and academic sectors. Especially, lignocellulose-based biomass can be utilized in the production of many aromatic platform chemicals suitable as substitutes for known fossil-based chemicals. For example, cellulose-derived 5-(hydroxymethyl)furfural has been utilized successfully for the aforementioned purposes. On the other hand, hemicellulose-derived furfural has received rather minor attention, even though recent studies show various excellent results in applications especially utilizing furfural. In this work, two novel furfural-derived epoxy resins were synthesized. Comparative studies were conducted with commercially available and widely used fossil-based epoxy resin, diglycidyl ether of bisphenol A. Resins were cured with methylhexahydrophthalic anhydride with optimized amounts of the 2-ethyl-4-methylimidazole initiator. Curing behaviors were studied with differential scanning calorimetry while thermomechanical properties were evaluated using dynamic mechanical analysis and thermal stabilities with thermogravimetric analysis. Adhesion strengths were tested with single-lap joint steel plate samples using a tensile tester. Tensile testing was also carried out for dog-bone-shaped resin specimens. Lastly, the water absorptions were evaluated through immersion in water. Results showed that the synthesized bioresins have great potential to replace diglycidyl ether of bisphenol A in various applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"29 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601587","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 : 2024-11-11DOI: 10.1021/acs.macromol.4c01863
Lei Lei, Naganatha Patil, Agathe Arnoux, Clémence Le Cœur, Yoann de Rancourt de Mimérand, Daniel Grande, Benjamin Le Droumaguet, Xiaoshuang Feng, Yves Gnanou, Benoit Couturaud
Semidegradable nanoparticles were synthesized in aqueous medium by photoinitiated polymerization-induced self-assembly, using a cleavable hydrophilic copolymer as a steric stabilizer that also served as a macromolecular chain transfer agent (mCTA) for the reversible addition–fragmentation chain transfer (RAFT) polymerization of 2-hydroxypropyl methacrylate (HPMA). This mCTA was obtained by modification of a pH-sensitive poly[(ethylene carbonate)-co-(ethylene oxide)] (PECEO) random copolymer that was end-fitted with a trithiocarbonate moiety. By adjusting the degree of polymerization of HPMA through RAFT, we achieved the synthesis of a series of amphiphilic block copolymers that self-assembled in various morphologies, including spheres, worms, and vesicles. Through characterization by 1H nuclear magnetic resonance, size exclusion chromatography, and transmission electron microscopy, it could be demonstrated that the carbonate linkages of their hydrophilic block and of their steric stabilizer undergo hydrolysis under alkaline conditions. The length of the PHPMA block and the balance between the hydrophilic and hydrophobic blocks are two parameters that have a significant impact on the self-assembly of these particles; a transition from steric to electrostatic stabilization of these nanoparticles could be witnessed during degradation for short PHPMA blocks. In summary, pH-sensitive nanoparticles sterically stabilized by degradable poly(ether-co-ether carbonate) copolymers gave rise under basic conditions to nanoparticles stabilized by electrostatic interaction.
{"title":"Transition from Steric to Electrostatic Stabilization in Shell-Degradable Waterborne Particles Obtained by Photopolymerization-Induced Self-Assembly","authors":"Lei Lei, Naganatha Patil, Agathe Arnoux, Clémence Le Cœur, Yoann de Rancourt de Mimérand, Daniel Grande, Benjamin Le Droumaguet, Xiaoshuang Feng, Yves Gnanou, Benoit Couturaud","doi":"10.1021/acs.macromol.4c01863","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01863","url":null,"abstract":"Semidegradable nanoparticles were synthesized in aqueous medium by photoinitiated polymerization-induced self-assembly, using a cleavable hydrophilic copolymer as a steric stabilizer that also served as a macromolecular chain transfer agent (mCTA) for the reversible addition–fragmentation chain transfer (RAFT) polymerization of 2-hydroxypropyl methacrylate (HPMA). This mCTA was obtained by modification of a pH-sensitive poly[(ethylene carbonate)-<i>co</i>-(ethylene oxide)] (PECEO) random copolymer that was end-fitted with a trithiocarbonate moiety. By adjusting the degree of polymerization of HPMA through RAFT, we achieved the synthesis of a series of amphiphilic block copolymers that self-assembled in various morphologies, including spheres, worms, and vesicles. Through characterization by <sup>1</sup>H nuclear magnetic resonance, size exclusion chromatography, and transmission electron microscopy, it could be demonstrated that the carbonate linkages of their hydrophilic block and of their steric stabilizer undergo hydrolysis under alkaline conditions. The length of the PHPMA block and the balance between the hydrophilic and hydrophobic blocks are two parameters that have a significant impact on the self-assembly of these particles; a transition from steric to electrostatic stabilization of these nanoparticles could be witnessed during degradation for short PHPMA blocks. In summary, pH-sensitive nanoparticles sterically stabilized by degradable poly(ether-<i>co</i>-ether carbonate) copolymers gave rise under basic conditions to nanoparticles stabilized by electrostatic interaction.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"35 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599136","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}
We introduce the Propagator-Biased Chain Generation (PBCG) algorithm, which generates initial configurations for coarse-grained molecular dynamics simulations of block copolymers presenting microphase separation. We build on the classical self-consistent field theory (SCFT) and show how its main statistical objects, the so-called forward and backward chain propagators, can be properly utilized to bias the configuration of coarse-grained bead–spring chains. Both the local volume fractions and the spatial segment distributions predicted by SCFT are accurately reproduced by configurations yielded by the algorithm. The PBCG algorithm supports the multiscale approach by allowing simulations to start in a state that is very close to the phase-separated equilibrium, typically much harder to obtain when starting from a random initial state. We demonstrate how to apply the algorithm to generic coarse-grained systems in reduced units as well as to chemically specific models of materials such as styrene-isoprene-styrene triblock copolymers.
{"title":"Propagator-Biased Chain Generation: Accurately Reverse Mapping Microphase-Separated Block Copolymers","authors":"Mateus Garcia Rodolfo, Joël Tchoufag, Florent Goujon, Alain Dequidt, Patrice Hauret, Patrice Malfreyt","doi":"10.1021/acs.macromol.4c01327","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01327","url":null,"abstract":"We introduce the Propagator-Biased Chain Generation (PBCG) algorithm, which generates initial configurations for coarse-grained molecular dynamics simulations of block copolymers presenting microphase separation. We build on the classical self-consistent field theory (SCFT) and show how its main statistical objects, the so-called forward and backward chain propagators, can be properly utilized to bias the configuration of coarse-grained bead–spring chains. Both the local volume fractions and the spatial segment distributions predicted by SCFT are accurately reproduced by configurations yielded by the algorithm. The PBCG algorithm supports the multiscale approach by allowing simulations to start in a state that is very close to the phase-separated equilibrium, typically much harder to obtain when starting from a random initial state. We demonstrate how to apply the algorithm to generic coarse-grained systems in reduced units as well as to chemically specific models of materials such as styrene-isoprene-styrene triblock copolymers.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"1 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599134","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 : 2024-11-08DOI: 10.1021/acs.macromol.4c02222
Fumihiko Tanaka
Chemical reactions in cross-linked polymer networks have long been a focus of polymer science because of their strong coupling to the network rheology. In particular, reversible reactions responding to various stimuli such as with thermal, pH, light, salt, and mechanical triggers promise broad applications to the development of new concepts and materials functions. Herein, rheological properties of cross-linked polymer networks made up of polymer chains, each undergoing reversible first-order chemical reaction A ⇄ B in response to such stimuli, are studied on the basis of the theoretical framework of the transient network model. We show that in general there are two fundamental relaxation times: one characterizing the rate of the reaction (chemical relaxation time) and the other the lifetime of the cross-links (rheological relaxation time). To see their interplay specifically, we focus on the formation of globules, flower micelles, loops, helices, etc., treated as first-order chemical reactions and calculate the dynamic mechanical moduli as functions of the rate constants of the reactions and the dissociation rate of the cross-links. In the limit of the permanent cross-links (reactive rubbers), we find a finite loss modulus that shows a peak at the frequency corresponding to the chemical relaxation time. The storage modulus is reduced but remains finite in the angular frequency range below this peak. The equilibrium storage modulus in the limit of ω = 0 is found as a function of the rate constants of the reaction. For the transient polymer networks with reversible cross-links of finite lifetime, competition of the two independent modes occurs: slow mode (rheological mode) and fast mode (chemical mode), corresponding to the two eigenvalues of the rate equation. Thus, we see that the complex modulus takes the form of the phenomenological Burgers model. Their relaxation times and plateau moduli are found in terms of molecular parameters. Viscoelastic properties of such reactive Burgersian fluids are studied in detail.
{"title":"Viscoelastic Properties of Stimuli-Responsive Transient Polymer Networks","authors":"Fumihiko Tanaka","doi":"10.1021/acs.macromol.4c02222","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02222","url":null,"abstract":"Chemical reactions in cross-linked polymer networks have long been a focus of polymer science because of their strong coupling to the network rheology. In particular, reversible reactions responding to various stimuli such as with thermal, pH, light, salt, and mechanical triggers promise broad applications to the development of new concepts and materials functions. Herein, rheological properties of cross-linked polymer networks made up of polymer chains, each undergoing reversible first-order chemical reaction A ⇄ B in response to such stimuli, are studied on the basis of the theoretical framework of the transient network model. We show that in general there are two fundamental relaxation times: one characterizing the rate of the reaction (chemical relaxation time) and the other the lifetime of the cross-links (rheological relaxation time). To see their interplay specifically, we focus on the formation of globules, flower micelles, loops, helices, etc., treated as first-order chemical reactions and calculate the dynamic mechanical moduli as functions of the rate constants of the reactions and the dissociation rate of the cross-links. In the limit of the permanent cross-links (reactive rubbers), we find a finite loss modulus that shows a peak at the frequency corresponding to the chemical relaxation time. The storage modulus is reduced but remains finite in the angular frequency range below this peak. The equilibrium storage modulus in the limit of ω = 0 is found as a function of the rate constants of the reaction. For the transient polymer networks with reversible cross-links of finite lifetime, competition of the two independent modes occurs: slow mode (rheological mode) and fast mode (chemical mode), corresponding to the two eigenvalues of the rate equation. Thus, we see that the complex modulus takes the form of the phenomenological Burgers model. Their relaxation times and plateau moduli are found in terms of molecular parameters. Viscoelastic properties of such reactive Burgersian fluids are studied in detail.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"9 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597627","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 : 2024-11-08DOI: 10.1021/acs.macromol.4c02147
Taejun Eom, Patrick T. Getty, Michael Czuczola, Christopher M. Bates, Craig J. Hawker
Silicone bottlebrush copolymers and networks derived from cyclic carbosiloxanes are reported and shown to have enhanced properties and recyclability compared with traditional dimethylsiloxane-based materials. The preparation of these materials is enabled by the synthesis of well-defined heterotelechelic macromonomers with Si–H and norbornene chain ends via anionic ring-opening polymerization of the hybrid carbosiloxane monomer 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane. These novel heterotelechelic α-Si–H/ω-norbornene macromonomers undergo efficient ring-opening metathesis copolymerization to yield functional bottlebrush polymers with accurate control over molecular weight and functional-group density. Si–H groups retained at the ends of side-chains after ring-opening metathesis copolymerization allow for the preparation of supersoft networks via hydrosilylation with cross-linkers such as tetrakis[dimethyl(vinyl)silyl]orthosilicate. In contrast to traditional PDMS systems, the incorporation of poly(carbosiloxane) side chains allows the resulting networks to be recycled back to the original monomer (>85% recovery) via depolymerization at elevated temperatures (250 °C) in the presence of base catalysts (potassium hydroxide and tetramethylammonium hydroxide). The recovered monomer was successfully repolymerized through anionic ring-opening polymerization with no decrease in structural fidelity or activity. In summary, this combination of unique (macro)monomer design and bottlebrush architecture creates new opportunities in sustainable practices by offering a robust, recyclable alternative to commercial silicone-based materials.
{"title":"Carbosiloxane Bottlebrush Networks for Enhanced Performance and Recyclability","authors":"Taejun Eom, Patrick T. Getty, Michael Czuczola, Christopher M. Bates, Craig J. Hawker","doi":"10.1021/acs.macromol.4c02147","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02147","url":null,"abstract":"Silicone bottlebrush copolymers and networks derived from cyclic carbosiloxanes are reported and shown to have enhanced properties and recyclability compared with traditional dimethylsiloxane-based materials. The preparation of these materials is enabled by the synthesis of well-defined heterotelechelic macromonomers with Si–H and norbornene chain ends via anionic ring-opening polymerization of the hybrid carbosiloxane monomer 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane. These novel heterotelechelic α-Si–H/ω-norbornene macromonomers undergo efficient ring-opening metathesis copolymerization to yield functional bottlebrush polymers with accurate control over molecular weight and functional-group density. Si–H groups retained at the ends of side-chains after ring-opening metathesis copolymerization allow for the preparation of supersoft networks via hydrosilylation with cross-linkers such as tetrakis[dimethyl(vinyl)silyl]orthosilicate. In contrast to traditional PDMS systems, the incorporation of poly(carbosiloxane) side chains allows the resulting networks to be recycled back to the original monomer (>85% recovery) via depolymerization at elevated temperatures (250 °C) in the presence of base catalysts (potassium hydroxide and tetramethylammonium hydroxide). The recovered monomer was successfully repolymerized through anionic ring-opening polymerization with no decrease in structural fidelity or activity. In summary, this combination of unique (macro)monomer design and bottlebrush architecture creates new opportunities in sustainable practices by offering a robust, recyclable alternative to commercial silicone-based materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"246 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597578","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 : 2024-11-08DOI: 10.1021/acs.macromol.4c02133
Chenhui Xu, Chuanbin An, Mengyuan Gao, Xuwen Zhang, Chunyong He, Weijia Dong, Tianzuo Wang, Yuqian Liu, Yunfeng Deng, Long Ye, Yang Han, Yanhou Geng
Morphological and electrical control over conjugated polymers has a great potential for the fabrication of high-performance organic thin-film transistors (OTFTs). Herein, we employed a multifunctional polymeric additive, namely, PBTTT-b-HTPB, to optimize the molecular packing order of an isoindigo-based model polymer (IIDSiC8) and simultaneously regulate the minority carriers for boosted transport properties in OTFTs via facile solution processing. By detailed comparative study, we demonstrated that PBTTT-b-HTPB remarkably improved the crystallinity of IIDSiC8 by forming elongated fibers with higher molecular order in a thin film, which originated from the larger size ordered solution aggregates due to the presence of the insulating block. On the other hand, the p-type conjugated block of PBTTT worked as a hole trapping center, resulting in significantly increased electron density, reduced off-current, and optimal n-type performance. Benefiting from the collaborative morphological and electrical regulation, IIDSiC8/PBTTT-b-HTPB films displayed well-aligned ordered morphology and a high electron mobility up close to 7 cm2 V–1 s–1 together with an on/off ratio of 106 in bar-coated OTFTs. The high electron mobility is among the top performance values reported for isoindigo-based polymers. Our work has achieved simultaneous optimization of film microstructures and carrier transport characteristics of polymer semiconductors, providing opportunities for the production of OTFT devices with a superior performance.
{"title":"Collaborative Morphological and Electrical Regulation of High-Mobility Conjugated Polymers via a Multifunctional Polymeric Additive","authors":"Chenhui Xu, Chuanbin An, Mengyuan Gao, Xuwen Zhang, Chunyong He, Weijia Dong, Tianzuo Wang, Yuqian Liu, Yunfeng Deng, Long Ye, Yang Han, Yanhou Geng","doi":"10.1021/acs.macromol.4c02133","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02133","url":null,"abstract":"Morphological and electrical control over conjugated polymers has a great potential for the fabrication of high-performance organic thin-film transistors (OTFTs). Herein, we employed a multifunctional polymeric additive, namely, PBTTT-<i>b</i>-HTPB, to optimize the molecular packing order of an isoindigo-based model polymer (IIDSiC8) and simultaneously regulate the minority carriers for boosted transport properties in OTFTs via facile solution processing. By detailed comparative study, we demonstrated that PBTTT-<i>b</i>-HTPB remarkably improved the crystallinity of IIDSiC8 by forming elongated fibers with higher molecular order in a thin film, which originated from the larger size ordered solution aggregates due to the presence of the insulating block. On the other hand, the p-type conjugated block of PBTTT worked as a hole trapping center, resulting in significantly increased electron density, reduced off-current, and optimal n-type performance. Benefiting from the collaborative morphological and electrical regulation, IIDSiC8/PBTTT-<i>b</i>-HTPB films displayed well-aligned ordered morphology and a high electron mobility up close to 7 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> together with an on/off ratio of 10<sup>6</sup> in bar-coated OTFTs. The high electron mobility is among the top performance values reported for isoindigo-based polymers. Our work has achieved simultaneous optimization of film microstructures and carrier transport characteristics of polymer semiconductors, providing opportunities for the production of OTFT devices with a superior performance.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"196 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597572","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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