Multiblock Copolymers Research Articles

New Multiblock Copolymers Containing Quaternary Ammonium Groups with Ultramicroporous Structure for High-Temperature Proton Exchange Membrane Fuel Cells

New Multiblock Copolymers Containing Quaternary Ammonium Groups with Ultramicroporous Structure for High-Temperature Proton Exchange Membrane Fuel Cells

Main-Chain Azobenzene Poly(ether ester) Multiblock Copolymers for Strong and Tough Light-Driven Actuators.

The stimulus-responsive polymeric materials have attracted great research interest, especially those remotely manipulated materials with potential applications in actuators and soft robotics. Here we report a photoresponsive main-chain actuator based on azobenzene poly(ether ester) multiblock copolymer (mBCP) thermoplastic elastomers, (PTAD-b-PTMO-b-PTAD)n, which were synthesized by a cascade polycondensation-coupling ring-opening polymerization method using poly(tetramethylene oxide) (PTMO) and azobenzene-containing cyclic oligoesters (COTADs) as monomers. The thermal, mechanical, and microphase separation behaviors of mBCPs could be flexibly tuned by altering the ratios of soft-to-hard segments and block number (n). The oriented azobenzene mBCP fibers were prepared by melt spinning, showing reversible photoresponsive properties with remarkably high strength (∼1000 MPa) and high elongation at break comparable to spider silks. Fast photoinduced bending and contraction were successfully achieved in these fibers with high work and power densities and energy conversion efficiency, enabling it to lift up about 250 times of its own weight. Moreover, it can take out materials inside the tube by UV-light control. These fibers could be applied in light-driven actuators or telecontrolled robot arms.

Boosting electrochemical performance by regulating rigid-flexible microphase separation of multiblock copolymers

The growth of lithium dendrites and associated safety issues hinder the further development of liquid lithium metal batteries. A novel rigid-flexible multiblock copolymer PBC-mb-PBS was successfully synthesized based on molecular design. Incorporating crystalline rigid phase polybutylene succinate (PBS) into PBC-mb-PBS significantly enhances its tensile strength and low-temperature toughness through physical crosslinking. The flexible polydibutyl 2-(2-cyanoethyl)malonate (PBC) phase with side-chain cyano groups facilitate ionic conduction, forming a LiN-rich stabilized interfacial layer, thereby improving oxidative stability and high-voltage cathode compatibility. A series of multiblock copolymers with varying segment lengths were synthesized to balance mechanical properties and ionic conductivity by adjusting microphase separation. The quasi-solid-state polymer electrolyte (QSPE), derived from PBC-mb-PBS with the molar block ratio of 0.42, exhibits optimal electrochemical performance with ionic conductivity of 6.20 × 10−5 S cm−1 at 30 °C and 4.22 × 10−4 S cm−1 at 60 °C. Due to its bicontinuous microphase structure, it also shows excellent mechanical strength and promotes uniform lithium deposition at high current densities. Li//LiFePO4 and Li//LiNi0.83Co0.05Mn0.12O2 cells demonstrate high capacity retention, confirming the potential of this polymer electrolyte in high-voltage applications. This design strategy offers insights for developing quasi-solid-state lithium metal batteries with superior overall performance.

Functionalized Polyisobutylene and Polyisobutylene‐Based Block Copolymers by Mechanistic Transformation from Cationic to Radical Process

AbstractThe strategy for the preparation of polyisobutylene‐based block copolymers via mechanistic transformation from cationic to radical polymerization is reported. This strategy involves the synthesis of 2‐bromo‐2‐methylpropanoyl‐terminated difunctional polyisobutylene macroinitiator (BiBB‐PIB‐BiBB) via consecutive cationic polymerization, in situ preparation of hydroxyl‐terminated polyisobutylene and its acylation by 2‐bromo‐2‐methylpropanoyl bromide. The Mn2(CO)10−triggered photo‐induced radical polymerization of styrene in bulk using this macroinitiator leads to the formation of multiblock copolymer, while predominantly triblock copolymer is generated during the polymerization of methyl methacrylate. The possibility to functionalize the polyisobutylene by pyrene via photo‐induced radical addition of 1‐bromomethyl pyrene in the presence of Mn2(CO)10 is also demonstrated in this work.

Fusible and Radiopaque Microspheres for Embolization.

In this work, fusible microspheres loaded with radiopaque agents as an embolic agent for transcatheter arterial embolization (TAE) are developed. A poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) multi-block copolymer basing polyurethane (PCEU) is synthesized and fabricated into blank microspheres (BMs). The microspheres are elastic in compression test. A clinical contrast agent lipiodol is encapsulated in the microspheres to receive fusible radiopaque microspheres (FRMs). The sizes of FRMs are uniform and range from 142.2 to 343.1µm. The encapsulated lipiodol acts as the plasticizer to reduce the melting temperature point (Tm) of PECU microspheres, thus, leading to the fusion of microspheres to exhibit efficient embolization in vivo. The performance of FRMs is carried out on a rabbit ear embolization model. Serious ischemic necrosis is observed and the radiopacity of FRMs sustains much longer time than that of commercial contrast agent Loversol in vivo. The fusible and radiopaque microsphere is promising to be developed as an exciting embolic agent.

Layered Porous Ring-Like Carbon Network Protected FeNi Metal Atomic Pairs for Bifunctional Oxygen Electrocatalysis and Rechargeable Zn-Air Batteries.

Bimetallic atom catalysts exhibit ultra-high oxygen electrocatalytic activity by harnessing mutual promotion and synergistic effects between adjacent metal active centers, surpassing the performance of single metal atomic catalysts. Herein, FeNi atom pairs protected by hierarchical porous annular carbon grids (P-FeNi-NPC) are introduced using a mediator-assisted MOFs-derived strategy. The introduction of the multi-block copolymer P123 ensures the uniform confinement and dispersion of metal ions, followed by thermal decomposition to form a "planetary-ring-like" carbon framework that anchors the bimetallic atomic pairs in the active region. The homogeneous distribution of adjacent Fe-N4 and Ni-N4 active sites significantly enhances catalytic activity and stability. Leveraging unique electronic and geometric structures, the resulting P-FeNi-NPC catalyst demonstrates exceptional ORR and OER activities with an ΔE value of 0.705 (E1/2 = 0.845V, Ej = 10 = 1.55V). Theoretical calculations unveil that FeNi bimetallic sites loaded on nitrogen-doped carbon frameworks with specific curvature effectively modulate the energy of d-band centers, thus balancing the free energy of oxygen-containing intermediates. This study presents a novel and versatile approach for synthesizing advanced bifunctional catalysts, poised to drive the future development of Zn-air batteries.

Identifying the location and micellization of PEG-b-PCL multiblock copolymers in PLA/PCL blends via AFM nanoscale IR spectroscopy

The IR absorption mapping of two multiblock copolymers based on poly(ethylene glycol) and poly(ε-caprolactone) segments (PEG-b-PCL) in poly(acid lactic) and poly(ε-caprolactone) blends (PLA/PCL) was performed via AFM nanoscale IR spectroscopy. These copolymers, having the same number average molar masses (Mn‾) but varying block sizes, were added into the blend in different amounts (1 and 5 wt%) using a co-rotating twin-screw extrusion. The results revealed that copolymers with smaller blocks are preferentially located near the interface when incorporated in small quantities. Increasing the copolymer content led to preferential diffusion into the PLA matrix. Compatibilization with the longer block-size copolymers also led to preferential diffusion in the PLA matrix, albeit with a tendency to form micelles. This hampers the overall mechanical properties of the blend, making the compatibilized blend more brittle than neat PLA. Compatibilization with the short block-size copolymers showed no micellization and improved the mechanical behavior of PLA/PCL.

The Block Copolymer Phase Behavior Database.

The Block Copolymer Database (BCDB) is a platform that allows users to search, submit, visualize, benchmark, and download experimental phase measurements and their associated characterization information for di- and multiblock copolymers. To the best of our knowledge, there is no widely accepted data model for publishing experimental and simulation data on block copolymer self-assembly. This proposed data schema with traceable information can accommodate any number of blocks and at the time of publication contains over 5400 block copolymer total melt phase measurements mined from the literature and manually curated and simulation data points of the phase diagram generated from self-consistent field theory that can rapidly be augmented. This database can be accessed via the Community Resource for Innovation in Polymer Technology (CRIPT) web application and the Materials Data Facility. The chemical structure of the polymer is encoded in BigSMILES, an extension of the Simplified Molecular-Input Line-Entry System (SMILES) into the macromolecular domain, and the user can search repeat units and functional groups using the SMARTS search syntax (SMILES Arbitrary Target Specification). The user can also query characterization and phase information using Structured Query Language (SQL) and download custom sets of block copolymer data to train machine learning models. Finally, a protocol is presented in which GPT-4, an AI-powered large language model, can be used to rapidly screen and identify block copolymer papers from the literature using only the abstract text and determine whether they have BCDB data, allowing the database to grow as the number of published papers on the World Wide Web increases. The F1 score for this model is 0.74. This platform is an important step in making polymer data more accessible to the broader community.

Is poly(propylene carbonate) biodegradable? Synthesis of poly(propylene carbonate)‐containing star and block copolymers and comprehensive investigation on their biodegradation

AbstractStoring CO2 and converting it into valuable substances are crucial for addressing climate change. While poly(propylene carbonate) (PPC), formed through the copolymerization of CO2 and propylene oxide, holds promise in commercial applications, practical limitations arise due to inherent property constraints. Additionally, the lack of systematic research on PPC biodegradation complicates its post‐use disposal. In this study, we synthesized various polymers, including PPC homopolymers, PPC/castor oil star copolymers, and PPC/poly(l‐lactic acid) multiblock copolymers (PPC‐mb‐PLLAs), not only to mitigate the brittle properties of PPC but also to systematically explore their biodegradability. Both natural soil and industrial composting conditions were employed to assess the biodegradation of the polymers. Furthermore, metagenomic analysis identified the microorganisms responsible for polymer degradation, offering valuable insights into the mechanism of the biodegradation process.

Bridge-rich and loop-less hydrogel networks through suppressed micellization of multiblock polyelectrolytes

Most triblock copolymer-based physical hydrogels form three-dimensional networks through micellar packing, and formation of polymer loops represents a topological defect that diminishes hydrogel elasticity. This effect can be mitigated by maximizing the fraction of elastically effective bridges in the hydrogel network. Herein, we report hydrogels constructed by complexing oppositely charged multiblock copolymers designed with a sequence pattern that maximizes the entropic and enthalpic penalty of micellization. These copolymers self-assemble into branched and bridge-rich network units (netmers), instead of forming sparsely interlinked micelles. We find that the storage modulus of the netmer-based hydrogel is 11.5 times higher than that of the micelle-based hydrogel. Complementary coarse grained molecular dynamics simulations reveal that in the netmer-based hydrogels, the numbers of charge-complexed nodes and mechanically reinforcing bridges increase substantially relative to micelle-based hydrogels.

Solid-Phase Synthesis of Well-Defined Multiblock Copolymers by Atom Transfer Radical Polymerization.

Solid-phase polymer synthesis, historically rooted in peptide synthesis, has evolved into a powerful method for achieving sequence-controlled macromolecules. This study explores solid-phase polymer synthesis by covalently immobilizing growing polymer chains onto a poly(ethylene glycol) (PEG)-based resin, known as ChemMatrix (CM) resin. In contrast to traditional hydrophobic supports, CM resin's amphiphilic properties enable swelling in both polar and nonpolar solvents, simplifying filtration, washing, and drying processes. Combining atom transfer radical polymerization (ATRP) with solid-phase techniques allowed for the grafting of well-defined block copolymers in high yields. This approach is attractive for sequence-controlled polymer synthesis, successfully synthesizing di-, tri-, tetra-, and penta-block copolymers with excellent control over the molecular weight and dispersity. The study also delves into the limitations of achieving high molecular weights due to confinement within resin pores. Moreover, the versatility of the method is demonstrated through its applicability to various monomers in organic and aqueous media. This straightforward approach offers a rapid route to developing tailored block copolymers with unique structures and functionalities.

The comparative study of PP-b-PE block copolymer and ethylene-octene block copolymer on crystallization, structure and mechanical property of high-density polyethylene/polypropylene blends

Olefin block copolymers can improve the compatibility between polyethylene (PE) and polypropylene (PP). The work studied the impact of ethylene-propylene multiblock copolymer (PP-b-PE) and ethylene-octene block copolymer (OBC) on the crystallization behavior, mechanical properties, phase structure, and interfacial interactions of HDPE/PP blends. The result showed that PP-b-PE promotes the crystallization temperature and rate of both HDPE and PP, while OBC primarily affects the crystallization behavior of HDPE. The addition of PP-b-PE, as evidenced by small angle X-ray scattering (SAXS), further weakened the interface region between HDPE and PP compared to OBC, indicating enhanced compatibility between HDPE and PP, further confirmed by the stronger adhesion of PP-b-PE to PP and HDPE compared to OBC in peel test. Surface morphology and surface energy analysis demonstrated that PP-b-PE can form a core-shell structure with PP by encapsulating PP, similar to OBC-PP core-shell structure, reducing the interfacial tension between HDPE and PP that effectively transfers stress to the PP phase. The improved compatibility of HDPE/PP resulted in higher elongation at break and equivalent impact strength to HDPE.

Deformation and failure of glassy polymer-polymer interfaces compatibilized by linear multiblock copolymers

Deformation and failure of glassy polymer-polymer interfaces compatibilized by linear multiblock copolymers

Metallosupramolecular Multiblock Copolymers of Lanthanide Complexes by Seeded Living Polymerization.

Supramolecular block copolymers, derived via seeded living polymerization, are increasingly recognized for their rich structural and functional diversity, marking them as cutting-edge materials. The use of metal complexes in supramolecular block copolymerization not only offers a broad range of block copolymers through the structural similarity in the coordination geometry of the central metal ion but also controls spectroscopic properties, such as emission wavelength, emission strength, and fluorescence lifetime. However, the exploration of metallosupramolecular multiblock copolymerization based on metal complexes remains quite limited. In this work, we present a pioneering synthesis of metallosupramolecular multiblock copolymers utilizing Eu3+ and Tb3+ complexes as building blocks. This is achieved through the strategic manipulation of nonequilibrium self-assemblies via a living supramolecular polymerization approach. Our comprehensive exploration of both thermodynamically and kinetically regulated metallosupramolecular polymerizations, centered around Eu3+ and Tb3+ complexes with bisterpyridine-modified ligands containing R-alanine units and a long alkyl group, has highlighted intriguing behaviors. The monomeric [R-L1Eu(NO3)3] complex generates a spherical structure as the kinetic product. In contrast, the monomeric [R-L1Eu2(NO3)6] complex generates fiber aggregates as a thermodynamic product through intermolecular interactions such as π-π stacking, hydrophobic interaction, and H-bonds. Utilizing the Eu3+ complex, we successfully conducted seed-induced living polymerization of the monomeric building unit under kinetically regulated conditions. This yielded a metallosupramolecular polymer of precisely controlled length with minimal polydispersity. Moreover, by copolymerizing the kinetically confined Tb3+ complex state ("A" species) with a seed derived from the Eu3+ complex ("B" species), we were able to fabricate metallosupramolecular tri- and pentablock copolymers with A-B-A, and B-A-B-A-B types, respectively, through a seed-end chain-growth mechanism.

Toward high-resolution 3D-printing of pharmaceutical implants – A holistic analysis of relevant material properties and process parameters

In this work, filament-based 3D-printing, the most widely used sub-category of material extrusion additive manufacturing (MEAM), is presented as a promising manufacturing platform for the production of subcutaneous implants. Print nozzle diameters as small as 100 µm were utilized demonstrating MEAM of advanced porous internal structures at the given cylindrical implant geometry of 2 mm × 40 mm. The bottlenecks related to high-resolution MEAM of subcutaneous implants are systematically analyzed and the print process is optimized accordingly. Custom synthesized biodegradable phase-separated poly(ether ester) multiblock copolymers exhibiting appropriate melt viscosity at comparatively low printing temperatures of 135 °C and 165 °C were utilized as 3D-printing feedstock. The print process was optimized to minimize thermomechanical polymer degradation by employing print speeds of 30 mm∙s−1 in combination with a nozzle diameter of 150 µm at layer heights of 110 µm. These results portray the basis for further development of subcutaneous implantable drug delivery systems where drug release profiles can be tailored through the adaption of the internal implant structure, which cannot be achieved using existing manufacturing techniques.

Fundamental Principles and Emerging Opportunities for Selectively‐Solvated Block Copolymer Networks in Nonpolar Media: A Perspective

AbstractBlock polymers remain an extensively studied class of macromolecules due to their ability to self‐organize spontaneously as a result of microphase separation into a variety of ordered nanostructures, depending on the number of contiguous sequences (“blocks”) present and their sequential arrangement. These polymers are classified as multifunctional since they exhibit two or more different property sets during application. In this work, the focus is on bicomponent block copolymers composed of soft and hard segments arranged as linear triblock or higher‐order multiblock copolymers and possessing the properties of a thermoplastic elastomer (TPE). Of particular interest are selectively‐solvated TPEs, designated as TPE gels (TPEGs), with precisely‐ and composition‐tunable properties. An important aspect of TPEs and their TPEG analogs is their elasticity, which reflects the ability of the soft block(s) to form a contiguous molecular network connected by dispersed microdomains composed of the hard block. Here, the origins of microphase separation and network formation in styrenic TPEs and TPEGs are explored, and experimental, theoretical, and simulation results are examined to elucidate chemistry‐structure‐property‐processing (CSPP) relationships in these self‐networking materials. Once such relationships are established, several unconventional technologies that can directly benefit from TPEGs, along with TPEGs fabricated from TPEs possessing different chemical moieties, are likewise considered.

Cell adhesion behavior of poly(l‐lactide‐co‐glycolide)‐poly(1,5‐dioxepan‐2‐one) random multiblock copolymers

AbstractAlthough bioabsorbable polymers are promising implant materials, implanting hydrophobic polymers induces platelet adhesions and subsequent thrombus formation. We recently reported that a multiblock copolymer composed of poly(l‐lactide‐co‐glycolide) (PLGA) and poly(1,5‐dioxepan‐2‐one) (PDXO) exhibited antiplatelet adhesive behavior. In this study, the cell adhesion behaviors of PLGA and PDXO random multiblock copolymers (PLGA−PDXO RMBCs) were examined. All the RMBCs showed antiplatelet adhesion behavior, and the copolymers containing 40 or 51 mol% of the PDXO component showed good antiplatelet adhesive behavior. Good culture behavior was observed for HeLa cells, but human umbilical vein endothelial cells (HUVECs) proliferation was poor on PLGA−PDXO RMBC surfaces. The cell attachment inhibition studies revealed that both integrin‐dependent and integrin‐independent interactions worked for HeLa cell culture, whereas only integrin‐dependent interactions played an important role for HUVEC culture proliferation on copolymer surfaces. The findings of this study revealed the unique cell‐selective adhesion behavior of PDXO containing multiblock polymers—being nonadhesive to platelets and HUVECs, and adhesive to HeLa cells.

Understanding the Interfacial and Self-Assembly Behavior of Multiblock Copolymers for Developing Compatibilizers toward Mechanical Recycling of Polymer Blends

Understanding the Interfacial and Self-Assembly Behavior of Multiblock Copolymers for Developing Compatibilizers toward Mechanical Recycling of Polymer Blends

استكشاف مفصل لتصنيع وتوصيف كوبولميرات متعددة الكتل من استر- سيلوكسان

This research paper presents a comprehensive study on the synthesis and characterization of Ester-Siloxane multi block copolymers. Two different synthesis methods, namely the one-prepolymer method and the two-prepolymer method, were employed to prepare the copolymers. The distribution of the Ester segment within the copolymers was analyzed using refractive index and ultraviolet detectors coupled with size exclusion chromatography (SEC). SEC-FTIR spectroscopy was utilized to investigate the distribution and composition of the Siloxane segment. Gel permeation chromatography (GEC) was employed to assess copolymer purity based on Siloxane content. Atomic force microscopy (AFM) was utilized to visualize the morphology of Siloxane domains in the copolymers. The results revealed the presence of well-defined Siloxane-rich domains in the form of spheres. Moreover, the occurrence of spherulitic crystal structures was observed in random copolymers with low Siloxane content and small Siloxane segment length. This research provides valuable insights into the manufacturing process, characterization, and structural aspects of multi-block ester-siloxane polymers, and contributes to the understanding of polymer design, the relationship between composition and molecular structure, and the material properties. Key words: Copolymer, -Siloxane multiblock, One-prepolymer, Two-prepolymer, Polycondensate.

Synthesis of block macro-CTAs by HNTs@Cu-catalyzed click reaction: Suitable CTAs for synthesizing multiblock polymers via RAFT polymerization

Multiblock copolymer macrochain-transfer agents (MBP-CTAs) can be used to synthesize MBPs in one pot via reversible addition-fragmentation chain-transfer (RAFT) polymerization. MBP-CTAs can be efficiently synthesized via a copper-catalyzed azide-alkyne cycloaddition reaction. However, traditional purification methods cannot sufficiently purify MBP-CTAs, resulting in the failure of RAFT. In this study, it was discovered that using a supported catalytic system, namely, Cu@A-HNTs, inhibited the connection between Cu and S. The residual Cu content in the MBP-CTA was successfully reduced to a low level (7.88 µg/mg). Then, hydrophilic and hydrophobic MBPs were synthesized through RAFT polymerization using the MBP-CTAs. Subsequently, multiblock copoly(methyl methacrylate-b-butyl methacrylate-CTA)s (PMMA-b-PBMA-c-CTA)s were successfully prepared. The MBP-CTAs and MBPs were characterized using ultraviolet–visible spectroscopy, 1H nuclear magnetic resonance, size-exclusion chromatography, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry, differential scanning calorimetry measurements and uniaxial tensile tests. The results of performance testing of PMMA-b-PBMA-c-CTAs demonstrated that their fracture stress and strain significantly increased comparing with that of PMMA-b-CTAs.