Pub Date : 2024-06-27DOI: 10.1021/acs.macromol.4c00847
Aya Katto, Sadahito Aoshima, Arihiro Kanazawa
Sugar-derived cyclic acetals were demonstrated to undergo cationic copolymerization with a vinyl ether (VE) via the vinyl-addition and ring-opening mechanisms. Cyclic acetals were synthesized by the condensation reactions of sugar alcohols (mannitol, xylose, erythritol, and sorbitol) with aldehydes or ketones. These cyclic acetals differ in the number of cyclic acetal moieties, the number of ring members, substituents, and stereo configuration. Such structural features greatly affected the copolymerization behavior. For example, erythritol-derived cyclic acetals consisting of two isolated five-membered cyclic acetal moieties undergo copolymerization with 2-chloroethyl VE, while mannitol-derived cyclic acetals consisting of three fused seven- and six-membered cyclic acetal moieties were not incorporated into polymer chains. Moreover, a xylose-derived cyclic acetal that has a p-methoxyphenyl substituent at the carbon atom adjacent to two oxygen atoms underwent copolymerization most effectively among the cyclic acetals examined in this study, which is likely due to the efficient generation of a carbocation via ring-opening. In addition, cationic initiators or Lewis acid catalysts affected the frequency of crossover reactions, resulting in a difference in incorporated ratios of sugar-derived cyclic acetals in polymer chains. The copolymers synthesized from VEs and sugar-derived cyclic acetals were degraded by acid via cleavage of the VE-to-cyclic acetal crossover reaction-derived acetal moieties in the main chain. A gluconic acid-derived cyclic acetal that has both cyclic acetal and cyclic hemiacetal ester moieties was ineffective for copolymerization with a VE, whereas an oxirane was successfully copolymerized with the gluconic acid-derived monomer via the ring-opening of the cyclic hemiacetal ester moiety.
研究证明，糖类衍生环缩醛可通过乙烯基加成和开环机制与乙烯基醚（VE）发生阳离子共聚。环状缩醛是通过糖醇（甘露醇、木糖、赤藓糖醇和山梨醇）与醛或酮的缩合反应合成的。这些环状缩醛在环状缩醛分子的数量、环状成员的数量、取代基和立体构型方面各不相同。这些结构特征在很大程度上影响了共聚行为。例如，赤藓糖醇衍生的环缩醛由两个孤立的五元环缩醛分子组成，可与 2-Cloroethyl VE 发生共聚，而甘露醇衍生的环缩醛由三个融合的七元和六元环缩醛分子组成，不能与聚合物链结合。此外，在本研究考察的环缩醛中，木糖衍生的环缩醛在邻近两个氧原子的碳原子上具有对甲氧基苯基取代基，能最有效地进行共聚，这可能是由于通过开环有效地生成了碳位。此外，阳离子引发剂或路易斯酸催化剂也会影响交叉反应的频率，从而导致聚合物链中糖环乙醛的掺入比例不同。由 VE 和糖衍生环缩醛合成的共聚物在酸的作用下通过裂解主链中 VE 到环缩醛交叉反应衍生的缩醛分子而降解。同时具有环缩醛和环半缩醛酯分子的葡萄糖酸衍生环缩醛无法与 VE 进行共聚，而环氧乙烷则可以通过环半缩醛酯分子的开环反应成功地与葡萄糖酸衍生单体进行共聚。
{"title":"Sugar-Derived Cyclic Acetals as Comonomers for Cationic Copolymerization with Vinyl Ethers","authors":"Aya Katto, Sadahito Aoshima, Arihiro Kanazawa","doi":"10.1021/acs.macromol.4c00847","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c00847","url":null,"abstract":"Sugar-derived cyclic acetals were demonstrated to undergo cationic copolymerization with a vinyl ether (VE) via the vinyl-addition and ring-opening mechanisms. Cyclic acetals were synthesized by the condensation reactions of sugar alcohols (mannitol, xylose, erythritol, and sorbitol) with aldehydes or ketones. These cyclic acetals differ in the number of cyclic acetal moieties, the number of ring members, substituents, and stereo configuration. Such structural features greatly affected the copolymerization behavior. For example, erythritol-derived cyclic acetals consisting of two isolated five-membered cyclic acetal moieties undergo copolymerization with 2-chloroethyl VE, while mannitol-derived cyclic acetals consisting of three fused seven- and six-membered cyclic acetal moieties were not incorporated into polymer chains. Moreover, a xylose-derived cyclic acetal that has a <i>p</i>-methoxyphenyl substituent at the carbon atom adjacent to two oxygen atoms underwent copolymerization most effectively among the cyclic acetals examined in this study, which is likely due to the efficient generation of a carbocation via ring-opening. In addition, cationic initiators or Lewis acid catalysts affected the frequency of crossover reactions, resulting in a difference in incorporated ratios of sugar-derived cyclic acetals in polymer chains. The copolymers synthesized from VEs and sugar-derived cyclic acetals were degraded by acid via cleavage of the VE-to-cyclic acetal crossover reaction-derived acetal moieties in the main chain. A gluconic acid-derived cyclic acetal that has both cyclic acetal and cyclic hemiacetal ester moieties was ineffective for copolymerization with a VE, whereas an oxirane was successfully copolymerized with the gluconic acid-derived monomer via the ring-opening of the cyclic hemiacetal ester moiety.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462066","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 report a direct topological reorganization between intermolecularly cross-linked polymers and single-chain nanoparticles (SCNPs) via thermal exchange reactions based on bis(2,2,6,6-tetramethylpiperidin-1-yl)disulfide (BiTEMPS) linkages. The network architecture of cross-linked poly(hexyl methacrylate) incorporating BiTEMPS at the cross-linking points can be directly transformed to SCNPs merely by heating in a dilute solution. Diffusion-ordered NMR spectroscopy and GPC analyses confirmed the smaller hydrodynamic radii of the SCNPs compared to those of the chain polymers obtained by de-cross-linking the original networks. The reverse transformation from the SCNPs to the polymer networks was achieved simply by heating under solvent-free conditions. Time-course monitoring of the storage moduli showed a clear increase as a function of heating time due to the restoration of the intermolecular cross-links via disulfide-exchange reactions. The restored cross-linked polymers exhibited comparable cross-linking densities and mechanical properties to those of the original cross-linked polymers, and the properties were again replicated well after an additional network–SCNP transformation cycle. Such an on-demand network-modulation feature enables a postsynthetic adjustment of the elastomer properties by, e.g., fusing SCNPs prepared from cross-linked polymers with different cross-linking densities.
{"title":"Direct and Reversible Transformations between Intermolecular Polymer Networks and Single-Chain Nanoparticles Based on Thermally Dissociable Bis(hindered amino)disulfide Linkages","authors":"Gota Tomono, Hirogi Yokochi, Akira Takahashi, Daisuke Aoki, Hideyuki Otsuka","doi":"10.1021/acs.macromol.4c00359","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c00359","url":null,"abstract":"We report a direct topological reorganization between intermolecularly cross-linked polymers and single-chain nanoparticles (SCNPs) via thermal exchange reactions based on bis(2,2,6,6-tetramethylpiperidin-1-yl)disulfide (BiTEMPS) linkages. The network architecture of cross-linked poly(hexyl methacrylate) incorporating BiTEMPS at the cross-linking points can be directly transformed to SCNPs merely by heating in a dilute solution. Diffusion-ordered NMR spectroscopy and GPC analyses confirmed the smaller hydrodynamic radii of the SCNPs compared to those of the chain polymers obtained by de-cross-linking the original networks. The reverse transformation from the SCNPs to the polymer networks was achieved simply by heating under solvent-free conditions. Time-course monitoring of the storage moduli showed a clear increase as a function of heating time due to the restoration of the intermolecular cross-links via disulfide-exchange reactions. The restored cross-linked polymers exhibited comparable cross-linking densities and mechanical properties to those of the original cross-linked polymers, and the properties were again replicated well after an additional network–SCNP transformation cycle. Such an on-demand network-modulation feature enables a postsynthetic adjustment of the elastomer properties by, e.g., fusing SCNPs prepared from cross-linked polymers with different cross-linking densities.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462001","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 : 2024-06-27DOI: 10.1021/acs.macromol.4c00895
Shengjie Wang, Xing Wang, Junshuai Ding, Zihao Zhu, Jingmin Wang, Li Shen, Alim Abdurahman, Geyu Lu, Jianpu Wang, Qiming Peng
Controlling the spin states to modulate their optical properties is crucial for spintronics and emerging quantum technologies. Open-shell luminescent diradicals are promising candidates for achieving this goal due to the independent spins. However, achieving spin-optical modulation in traditional diradicals still faces significant challenges owing to low luminescence efficiency and inevitable aggregate effects. In this study, we first achieved efficient luminescence of a diradical by suspending luminescent diradicals on a polymer main chain. The resulting diradical polymer exhibits a high photoluminescence efficiency of 44.0% in the condensed state along with excellent photostability. Most importantly, we have demonstrated successful spin-state manipulation through temperature control and application of a magnetic field. These findings open up new avenues for spin-optical modulation based on luminescent diradical materials, providing important guidance for the development spin-optoelectronics.
{"title":"Spin-State Manipulation in a Luminescent Diradical Polymer","authors":"Shengjie Wang, Xing Wang, Junshuai Ding, Zihao Zhu, Jingmin Wang, Li Shen, Alim Abdurahman, Geyu Lu, Jianpu Wang, Qiming Peng","doi":"10.1021/acs.macromol.4c00895","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c00895","url":null,"abstract":"Controlling the spin states to modulate their optical properties is crucial for spintronics and emerging quantum technologies. Open-shell luminescent diradicals are promising candidates for achieving this goal due to the independent spins. However, achieving spin-optical modulation in traditional diradicals still faces significant challenges owing to low luminescence efficiency and inevitable aggregate effects. In this study, we first achieved efficient luminescence of a diradical by suspending luminescent diradicals on a polymer main chain. The resulting diradical polymer exhibits a high photoluminescence efficiency of 44.0% in the condensed state along with excellent photostability. Most importantly, we have demonstrated successful spin-state manipulation through temperature control and application of a magnetic field. These findings open up new avenues for spin-optical modulation based on luminescent diradical materials, providing important guidance for the development spin-optoelectronics.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462121","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 : 2024-06-27DOI: 10.1021/acs.macromol.4c00981
Jialin Wang, Longfei Zhang, Du Chen, Chenyu Wang, Ziye Ren, Zhao Wang
Radical ring-opening polymerization (rROP) of vinylcyclopropanes (VCPs) represents an important class of polymerization reactions. Despite the versatility of atom transfer radical polymerization (ATRP) in accessing well-defined polymers, the rROP of VCPs by Cu-catalyzed ATRP remains a formidable challenge. In this study, we propose an efficient mechanically controlled ATRP (mechano-ATRP) approach for different VCPs. This process utilized a mesoporous ZnO (m-ZnO), which effectively prevents Cu catalyst poisoning and promotes the rROP process. The coordination environment of VCP with Cu and a polymer on the m-ZnO surface was confirmed by experimental observations and calculations. The mechano-ATRP yielded poly(VCPs) with a predictable molecular weight, low dispersity, and high chain-end fidelity. This method was employed in the vinylcyclopropane-based resin curing process. The incorporation of m-ZnO can enhance the mechanical properties and reduce the volume shrinkage of the resin. Furthermore, the application of the m-ZnO film as an external catalyst enabled the production of a transparent resin.
{"title":"A Mechanoredox Catalyst Facilitates ATRP of Vinylcyclopropanes","authors":"Jialin Wang, Longfei Zhang, Du Chen, Chenyu Wang, Ziye Ren, Zhao Wang","doi":"10.1021/acs.macromol.4c00981","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c00981","url":null,"abstract":"Radical ring-opening polymerization (rROP) of vinylcyclopropanes (VCPs) represents an important class of polymerization reactions. Despite the versatility of atom transfer radical polymerization (ATRP) in accessing well-defined polymers, the rROP of VCPs by Cu-catalyzed ATRP remains a formidable challenge. In this study, we propose an efficient mechanically controlled ATRP (mechano-ATRP) approach for different VCPs. This process utilized a mesoporous ZnO (m-ZnO), which effectively prevents Cu catalyst poisoning and promotes the rROP process. The coordination environment of VCP with Cu and a polymer on the m-ZnO surface was confirmed by experimental observations and calculations. The mechano-ATRP yielded poly(VCPs) with a predictable molecular weight, low dispersity, and high chain-end fidelity. This method was employed in the vinylcyclopropane-based resin curing process. The incorporation of m-ZnO can enhance the mechanical properties and reduce the volume shrinkage of the resin. Furthermore, the application of the m-ZnO film as an external catalyst enabled the production of a transparent resin.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141463735","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 : 2024-06-26DOI: 10.1021/acs.macromol.4c01098
Yahui Li, Yao Li, Renkuan Cao, Jiayu Xie, Wei Chen
Mechanical behavior of the cross-linked polymer system is modulated by various cross-linkings, i.e., chemical and physical cross-linking. The poly(vinyl alcohol) (PVA)–boric acid (BA) cross-linking system is known to exhibit cross-linking-induced stiffening behavior. In this study, the step-cycle mechanical tests reveal that the addition of BA not only enhances the chain modulus but also amplifies the mechanical resilience within a BA concentration range of 0.1–2.0 wt %. This structural origin is attributed to the effect of BA on the interpenetrated network consisting of (i) a crystallite-based network and (ii) a chain network in the amorphous domain. For the crystallite-based network, the lamella thickness of crystallites remains nearly constant at middle BA addition levels (0.1 wt % < cBA < 2.0 wt %), whereas the selective destruction of (100) and (200) planes over (101)/(101̅) planes is observed, as evidenced by synchrotron radiation X-ray scattering (wide- and small-angle X-ray scattering). This preserves the skeleton of the crystallite-based network. Various time-domain nuclear magnetic resonance techniques, i.e., 1H T2 relaxometry and 1H double-quantum NMR, quantitatively present the linear relationship between cross-linking density and modulus in the amorphous domain. These findings contribute to the understanding of the deformation mechanism of the PVA–BA cross-linking system during loading–unloading tests.
交联聚合物体系的机械性能受各种交联（即化学和物理交联）的影响。众所周知，聚乙烯醇（PVA）-硼酸（BA）交联体系表现出交联诱导的刚性行为。在这项研究中，阶跃循环机械测试表明，在 BA 浓度为 0.1-2.0 wt % 的范围内，添加 BA 不仅能提高链模量，还能增强机械回弹性。这种结构起源于 BA 对互渗网络的影响，该网络由 (i) 基于晶体的网络和 (ii) 非晶态域中的链网络组成。对于基于晶粒的网络，在中间 BA 添加水平（0.1 wt % < cBA < 2.0 wt %）下，晶粒的薄片厚度几乎保持不变，而同步辐射 X 射线散射（广角和小角 X 射线散射）证明，(100) 和 (200) 平面比 (101)/(101̅) 平面有选择性地破坏。这保留了基于晶体的网络骨架。各种时域核磁共振技术，即 1H T2 弛豫测定法和 1H 双量子核磁共振，定量呈现了交联密度与无定形域模量之间的线性关系。这些发现有助于理解 PVA-BA 交联体系在加载-卸载试验中的变形机制。
{"title":"Amplifying the Mechanical Resilience of Chemically Cross-Linked Poly(vinyl alcohol) Films with the Addition of Boric Acid","authors":"Yahui Li, Yao Li, Renkuan Cao, Jiayu Xie, Wei Chen","doi":"10.1021/acs.macromol.4c01098","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01098","url":null,"abstract":"Mechanical behavior of the cross-linked polymer system is modulated by various cross-linkings, i.e., chemical and physical cross-linking. The poly(vinyl alcohol) (PVA)–boric acid (BA) cross-linking system is known to exhibit cross-linking-induced stiffening behavior. In this study, the step-cycle mechanical tests reveal that the addition of BA not only enhances the chain modulus but also amplifies the mechanical resilience within a BA concentration range of 0.1–2.0 wt %. This structural origin is attributed to the effect of BA on the interpenetrated network consisting of (i) a crystallite-based network and (ii) a chain network in the amorphous domain. For the crystallite-based network, the lamella thickness of crystallites remains nearly constant at middle BA addition levels (0.1 wt % < <i>c</i><sub>BA</sub> < 2.0 wt %), whereas the selective destruction of (100) and (200) planes over (101)/(101̅) planes is observed, as evidenced by synchrotron radiation X-ray scattering (wide- and small-angle X-ray scattering). This preserves the skeleton of the crystallite-based network. Various time-domain nuclear magnetic resonance techniques, i.e., <sup>1</sup>H <i>T</i><sub>2</sub> relaxometry and <sup>1</sup>H double-quantum NMR, quantitatively present the linear relationship between cross-linking density and modulus in the amorphous domain. These findings contribute to the understanding of the deformation mechanism of the PVA–BA cross-linking system during loading–unloading tests.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141463738","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 : 2024-06-26DOI: 10.1021/acs.macromol.4c01018
Michael J. Boyle, Ravi Radhakrishnan, Russell J. Composto
Because surface-grafted polyelectrolyte brushes (PEBs) are responsive to external stimuli, such as electric fields and ionic strength, PEBs are attractive for applications ranging from drug delivery to separation technologies. Essential to PEB utilization is understanding how critical parameters like grafting density (σ) impact the PEB structure and the dynamics of the PEB and counterions. To study the effect of σ on PEB and the counterion structure and dynamics, we fine-tune a coarse-grained model that retains the chemical specificity of a strong polyelectrolyte, poly[(2-(methacryloyloxy)ethyl) trimethylammonium chloride] (PMETAC), using the MARTINI force field. Using “salt-free” conditions where the counterion concentration balances the charge on the brush, we build coarse-grained (CG) molecular dynamics simulations for MARTINI PMETAC brushes (N = 150 monomers; MW = 31.2 kg/mol) at experimentally relevant values of σ = 0.05, 0.10, 0.20, and 0.40 chains/nm2. Using 5 μs simulations, we investigate the effects of grafting density on the PEB structure, ion dissociation dynamics, polymer mobility, and counterion diffusivity. Results show that competition between electrostatic interactions, steric hindrance, and polymer mobility controls counterion diffusivity. The interplay of these factors leads to diffusivity that depends non-monotonically on σ, with counterion diffusivity peaking at an intermediate σ = 0.10 chains/nm2.
{"title":"Molecular Dynamics Study of the Effect of Grafting Density on Ion Diffusivity in a MARTINI Coarse-Grained Strong Polyelectrolyte Brush","authors":"Michael J. Boyle, Ravi Radhakrishnan, Russell J. Composto","doi":"10.1021/acs.macromol.4c01018","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01018","url":null,"abstract":"Because surface-grafted polyelectrolyte brushes (PEBs) are responsive to external stimuli, such as electric fields and ionic strength, PEBs are attractive for applications ranging from drug delivery to separation technologies. Essential to PEB utilization is understanding how critical parameters like grafting density (σ) impact the PEB structure and the dynamics of the PEB and counterions. To study the effect of σ on PEB and the counterion structure and dynamics, we fine-tune a coarse-grained model that retains the chemical specificity of a strong polyelectrolyte, poly[(2-(methacryloyloxy)ethyl) trimethylammonium chloride] (PMETAC), using the MARTINI force field. Using “salt-free” conditions where the counterion concentration balances the charge on the brush, we build coarse-grained (CG) molecular dynamics simulations for MARTINI PMETAC brushes (<i>N</i> = 150 monomers; <i>M</i><sub>W</sub> = 31.2 kg/mol) at experimentally relevant values of σ = 0.05, 0.10, 0.20, and 0.40 chains/nm<sup>2</sup>. Using 5 μs simulations, we investigate the effects of grafting density on the PEB structure, ion dissociation dynamics, polymer mobility, and counterion diffusivity. Results show that competition between electrostatic interactions, steric hindrance, and polymer mobility controls counterion diffusivity. The interplay of these factors leads to diffusivity that depends non-monotonically on σ, with counterion diffusivity peaking at an intermediate σ = 0.10 chains/nm<sup>2</sup>.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141463748","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 better understanding of the dynamic behavior of polymer chains on solid surfaces is indispensable for the design and construction of high-performance polymer composites. We herein visualized the in-plane movement of isolated poly(methyl methacrylate) (PMMA) and poly(tert-butyl methacrylate) (PtBMA) single chains on hydrophilic silicon wafers under ambient conditions by atomic force microscopy. Isolated PMMA chains adsorbed to the substrate, whereas PtBMA chains diffused, the degree of which was dependent on the humidity. Neutron reflectivity revealed the formation of a layer of condensed water on the substrate. All-atomistic molecular dynamics simulations implied that the diffusivity difference of the two polymers was based on the submerged depth in which a part of a chain existed. That is, the interaction of a polymer with the surface of the hydrophilic substrate primarily governs its lateral movement, or adsorption behavior, facilitated by the presence of water.
{"title":"In-Plane Movement of Isolated Poly(methacrylate) Chains on a Hydrophilic Solid Surface","authors":"Masayuki Kawano, Yuma Morimitsu, Yuwei Liu, Noboru Miyata, Tsukasa Miyazaki, Hiroyuki Aoki, Daisuke Kawaguchi, Satoru Yamamoto, Keiji Tanaka","doi":"10.1021/acs.macromol.4c00724","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c00724","url":null,"abstract":"A better understanding of the dynamic behavior of polymer chains on solid surfaces is indispensable for the design and construction of high-performance polymer composites. We herein visualized the in-plane movement of isolated poly(methyl methacrylate) (PMMA) and poly(<i>tert</i>-butyl methacrylate) (P<i>t</i>BMA) single chains on hydrophilic silicon wafers under ambient conditions by atomic force microscopy. Isolated PMMA chains adsorbed to the substrate, whereas P<i>t</i>BMA chains diffused, the degree of which was dependent on the humidity. Neutron reflectivity revealed the formation of a layer of condensed water on the substrate. All-atomistic molecular dynamics simulations implied that the diffusivity difference of the two polymers was based on the submerged depth in which a part of a chain existed. That is, the interaction of a polymer with the surface of the hydrophilic substrate primarily governs its lateral movement, or adsorption behavior, facilitated by the presence of water.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462059","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}
Herein, a peculiar phase transition between the mesochiral and achiral networks can be found in the self-assembly of chiral block copolymers. A chiral network phase, an alternating gyroid (GA), with controlled helicity can be achieved by the self-assembly of chiral triblock terpolymers, polyisoprene-block-polystyrene-block-poly(l-lactide) (PI–PS-PLLA), and polyisoprene-block-polystyrene-block-poly(d-lactide) (PI–PS-PDLA). An interesting phase transition between chiral GA with negative PLLA network and positive PI network within the PS matrix and core–shell double gyroid (DG) with a pair of PLLA networks but opposite handedness with PS shells in the PI matrix can be found, reflecting a phase transformation between the dispersed PI network and PI matrix with minor compositional variation. Similar results can also be found in the case of PDLA but with opposite handedness. Homochiral evolution at different length scales via self-assembly can be evidenced by vibrational circular dichroism (VCD) spectra of C═O stretching (conformational chirality due to intrachain chiral interaction) and the C–O–C parallel mode (hierarchical chirality due to interchain chiral interaction). Most interestingly, the molecular dispositions of the helical polymer chains in the self-assembled phase based on the VCD results of the C–O–C parallel mode are in line with the observed phase behaviors at which the VCD signals from GA will be nullified after the formation of the core–shell DG. As a result, the transition mechanism can be clarified from the conformational level to the mesoscale with respect to the self-assembly process.
在这里，手性嵌段共聚物的自组装可以发现介手性网络和非手性网络之间的奇特相变。手性三嵌段三元共聚物（聚异戊二烯-嵌段-聚苯乙烯-嵌段-聚（l-内酰胺）（PI-PS-PLLA）和聚异戊二烯-嵌段-聚苯乙烯-嵌段-聚（d-内酰胺）（PI-PS-PDLA））的自组装可实现具有可控螺旋度的手性网络相--交替陀螺（GA）。在 PS 基质中具有负 PLLA 网络和正 PI 网络的手性 GA 与在 PI 基质中具有一对 PLLA 网络但与 PS 外壳手性相反的核壳双陀螺（DG）之间发现了有趣的相变，这反映了分散的 PI 网络与 PI 基质之间的相变，其成分变化很小。在使用 PDLA 但手性相反的情况下，也可以发现类似的结果。C═O 伸展（链内手性相互作用导致的构象手性）和 C-O-C 平行模式（链间手性相互作用导致的层次手性）的振动圆二色性 (VCD) 光谱证明了通过自组装在不同长度尺度上的同手性演变。最有趣的是，根据 C-O-C 平行模式的 VCD 结果得出的自组装相中螺旋聚合物链的分子布局与观察到的相行为一致，在形成核壳 DG 后，GA 的 VCD 信号将在该相中失效。因此，可以从构象水平到中观尺度阐明自组装过程的过渡机制。
{"title":"Peculiar Transition between Chiral and Achiral Networks in Self-Assembly of Chiral Block Copolymers","authors":"Sook-Hui Lien, Pin-Hua Lin, Sheng-Wei Shao, Po-Ting Chiu, Cheng-Yen Chang, Yu-Chuan Sung, Jing-Cherng Tsai, Rong-Ming Ho","doi":"10.1021/acs.macromol.4c00361","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c00361","url":null,"abstract":"Herein, a peculiar phase transition between the mesochiral and achiral networks can be found in the self-assembly of chiral block copolymers. A chiral network phase, an alternating gyroid (G<sup>A</sup>), with controlled helicity can be achieved by the self-assembly of chiral triblock terpolymers, polyisoprene-<i>block</i>-polystyrene-<i>block</i>-poly(<span>l</span>-lactide) (PI–PS-PLLA), and polyisoprene-<i>block</i>-polystyrene-<i>block</i>-poly(<span>d</span>-lactide) (PI–PS-PDLA). An interesting phase transition between chiral G<sup>A</sup> with negative PLLA network and positive PI network within the PS matrix and core–shell double gyroid (DG) with a pair of PLLA networks but opposite handedness with PS shells in the PI matrix can be found, reflecting a phase transformation between the dispersed PI network and PI matrix with minor compositional variation. Similar results can also be found in the case of PDLA but with opposite handedness. Homochiral evolution at different length scales via self-assembly can be evidenced by vibrational circular dichroism (VCD) spectra of C═O stretching (conformational chirality due to intrachain chiral interaction) and the C–O–C parallel mode (hierarchical chirality due to interchain chiral interaction). Most interestingly, the molecular dispositions of the helical polymer chains in the self-assembled phase based on the VCD results of the C–O–C parallel mode are in line with the observed phase behaviors at which the VCD signals from G<sup>A</sup> will be nullified after the formation of the core–shell DG. As a result, the transition mechanism can be clarified from the conformational level to the mesoscale with respect to the self-assembly process.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462110","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 : 2024-06-25DOI: 10.1021/acs.macromol.4c00275
Hui Tian, Yifan Wang, Chunji Wu, Baoli Wang
Polyethylene (PE) and polystyrene (PS) are commercial plastics with large amounts of output, and their wastes have brought serious burden to our living environment. These usually exist as PE/PS mixtures and are hard or expensive to sort in some cases. PE/PS blends have poor mechanical properties due to thermodynamic incompatibilization. In principle, ethylene/(phenyl functionalized α-olefin) copolymers (containing PE and continuous phenyl α-olefin segments on one polymeric chain) would be good compatibilizers for PE/PS, but the synthesis of corresponding copolymers is much more difficult. Herein, we report the synthesis of ethylene-styrene (E-St), ethylene-allylbenzene (E-AP), and ethylene-(4-phenyl-1-butene) (E-BP) copolymers containing continuous comonomer segments via the copolymerization of E with various phenyl functionalized α-olefin monomers (St, AP, and BP) catalyzed by thiophene-fused cyclopentadienyl scandium complexes and study the compatibilization of resultant copolymers for HDPE/PS blends by using tensile test experiment and SEM and TEM analyses. E-BP copolymers behaved like adhesive materials with high BP incorporation ranged from 13.5 to 24.1 mol % and showed better compatibilization effect for HDPE/PS blends compared with E-St and E-AP, probably because of the longer distance between the polymeric main chain and phenyl group on its molecular structure, which favors the intermolecular π–π interaction between E-BP and PS during melting mixing. HDPE/PS/P4 (weight ratio: 80/20/2) blend (P4: E-BP copolymer with 24.1 mol % BP content) exhibited the greatest improvement in elongation at break (1397%), which showed a 26.3% increase, compared with the uncompatibilized HDPE/PS (80/20) blend and reached 91.5% of ultimate elongation of pure HDPE, and its tensile stress was also close to that of HDPE, indicating that P4 could be used as an effective compatibilizer for HDPE/PS mixtures that are difficult or expensive to sort.
{"title":"A Compatibilizing Strategy for Upcycling Polyethylene and Polystyrene with Ethylene/(Phenyl Functionalized α-Olefin) Copolymers Containing Continuous Comonomer Segments","authors":"Hui Tian, Yifan Wang, Chunji Wu, Baoli Wang","doi":"10.1021/acs.macromol.4c00275","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c00275","url":null,"abstract":"Polyethylene (PE) and polystyrene (PS) are commercial plastics with large amounts of output, and their wastes have brought serious burden to our living environment. These usually exist as PE/PS mixtures and are hard or expensive to sort in some cases. PE/PS blends have poor mechanical properties due to thermodynamic incompatibilization. In principle, ethylene/(phenyl functionalized α-olefin) copolymers (containing PE and continuous phenyl α-olefin segments on one polymeric chain) would be good compatibilizers for PE/PS, but the synthesis of corresponding copolymers is much more difficult. Herein, we report the synthesis of ethylene-styrene (<b>E</b>-<b>St</b>), ethylene-allylbenzene (<b>E</b>-<b>AP</b>), and ethylene-(4-phenyl-1-butene) (<b>E</b>-<b>BP</b>) copolymers containing continuous comonomer segments via the copolymerization of <b>E</b> with various phenyl functionalized α-olefin monomers (<b>St</b>, <b>AP</b>, and <b>BP)</b> catalyzed by thiophene-fused cyclopentadienyl scandium complexes and study the compatibilization of resultant copolymers for HDPE/PS blends by using tensile test experiment and SEM and TEM analyses. <b>E</b>-<b>BP</b> copolymers behaved like adhesive materials with high <b>BP</b> incorporation ranged from 13.5 to 24.1 mol % and showed better compatibilization effect for HDPE/PS blends compared with <b>E</b>-<b>St</b> and <b>E</b>-<b>AP</b>, probably because of the longer distance between the polymeric main chain and phenyl group on its molecular structure, which favors the intermolecular π–π interaction between <b>E</b>-<b>BP</b> and PS during melting mixing. HDPE/PS/<b>P4</b> (weight ratio: 80/20/2) blend (<b>P4</b>: <b>E</b>-<b>BP</b> copolymer with 24.1 mol % <b>BP</b> content) exhibited the greatest improvement in elongation at break (1397%), which showed a 26.3% increase, compared with the uncompatibilized HDPE/PS (80/20) blend and reached 91.5% of ultimate elongation of pure HDPE, and its tensile stress was also close to that of HDPE, indicating that <b>P4</b> could be used as an effective compatibilizer for HDPE/PS mixtures that are difficult or expensive to sort.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462002","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 : 2024-06-25DOI: 10.1021/acs.macromol.4c00800
Ran Xu, Zhixi Zhao, Fei Chen, Chen Qiu, Chuxiang Zhou, Yang Chen, Mei Liang, Ying Wu, Xiaoqiang Pan, Jing Yang, Zhengguang Heng, Huawei Zou
The polymer materials in nuclear facilities are exposed to high temperatures, radiation, and high loads. Their excellent heat resistance, radiation resistance, and shielding properties are important for the safe operation of nuclear facilities. In this study, 1,2-bis(hydroxymethyl)carborane (CBOH) was first synthesized in large quantities through water extraction and then introduced into an epoxy resin cross-linked network. The incorporation of a carborane structure significantly improved the heat resistance of epoxy. Under air atmosphere, the T5% (the temperature at 5 wt % degradation), T10% (the temperature at 10 wt % degradation), and char yield at 800 °C of the materials were 315.67 °C (16.51 °C increased), 326.29 °C (12.96 °C increased), and 33.22% (33.22% increased), respectively. The maximum decomposition temperature of the material increased from 550 to 750 °C, and 7.05 wt % of the carbon constituent was protected after thermal degradation at 800 °C. The glass transition temperature (Tg) of the materials greatly increased up to over 300 °C after introducing the carborane structure into the networks. The radiation resistance of the material was enhanced due to the in situ capture of oxygen radicals by the carborane structure. Moreover, the incorporation of carborane structure also increased the content of H and B in materials, improving their neutron-shielding capability. This work confers multifunctionality to epoxy resin and enhances its various properties, ensuring the safety of epoxy resin in nuclear facilities.
{"title":"Preparation of Structural Heat-and-Radiation-Resistant Integrated Epoxy by Constructing a Carborane-Hybridized Cross-Linked Network","authors":"Ran Xu, Zhixi Zhao, Fei Chen, Chen Qiu, Chuxiang Zhou, Yang Chen, Mei Liang, Ying Wu, Xiaoqiang Pan, Jing Yang, Zhengguang Heng, Huawei Zou","doi":"10.1021/acs.macromol.4c00800","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c00800","url":null,"abstract":"The polymer materials in nuclear facilities are exposed to high temperatures, radiation, and high loads. Their excellent heat resistance, radiation resistance, and shielding properties are important for the safe operation of nuclear facilities. In this study, 1,2-bis(hydroxymethyl)carborane (CBOH) was first synthesized in large quantities through water extraction and then introduced into an epoxy resin cross-linked network. The incorporation of a carborane structure significantly improved the heat resistance of epoxy. Under air atmosphere, the <i>T</i><sub>5%</sub> (the temperature at 5 wt % degradation), <i>T</i><sub>10%</sub> (the temperature at 10 wt % degradation), and char yield at 800 °C of the materials were 315.67 °C (16.51 °C increased), 326.29 °C (12.96 °C increased), and 33.22% (33.22% increased), respectively. The maximum decomposition temperature of the material increased from 550 to 750 °C, and 7.05 wt % of the carbon constituent was protected after thermal degradation at 800 °C. The glass transition temperature (<i>T</i><sub>g</sub>) of the materials greatly increased up to over 300 °C after introducing the carborane structure into the networks. The radiation resistance of the material was enhanced due to the in situ capture of oxygen radicals by the carborane structure. Moreover, the incorporation of carborane structure also increased the content of H and B in materials, improving their neutron-shielding capability. This work confers multifunctionality to epoxy resin and enhances its various properties, ensuring the safety of epoxy resin in nuclear facilities.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462028","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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