Showing papers on "Copolymer published in 2022"

A Brief Review of Poly (Butylene Succinate) (PBS) and Its Main Copolymers: Synthesis, Blends, Composites, Biodegradability, and Applications

Abstract: PBS, an acronym for poly (butylene succinate), is an aliphatic polyester that is attracting increasing attention due to the possibility of bio-based production, as well as its balanced properties, enhanced processability, and excellent biodegradability. This brief review has the aim to provide the status concerning the synthesis, production, thermal, morphological and mechanical properties underlying biodegradation ability, and major applications of PBS and its principal copolymers.

An Ionic Cluster Strategy for Performance Improvements and Product Morphology Control in Metal-Catalyzed Olefin-Polar Monomer Copolymerization.

Abstract: Product morphology control represents a critical challenge for polyolefin production, but it has remained largely unexplored in the field of ethylene-polar monomer copolymerization. Herein, an ionic cluster strategy was designed to control the product morphology during the synthesis of polar-functionalized polyolefins via precipitation polymerization. In addition to product morphology control, simultaneous improvements in the catalytic copolymerization performance (activities, copolymer molecular weights, and comonomer incorporation ratios) were achieved. These results were due to less poisoning of the metal-salt-based comonomers compared with their ester counterparts and the high local concentration of the alkene comonomers induced by ionic cluster formation. Moreover, the ionic cluster strategy is generally applicable to various comonomers and catalytic systems, greatly enhances the catalyst's thermal stability at high temperatures (90-150 °C), and enables the homopolymerization of both terminal and internal polar-functionalized olefins. Finally, polar-functionalized polyolefins and polyolefin composites (generated from a tandem process combining a prepolymerization step and subsequent polymerization) were developed, which showed tunable mechanical properties and great potential as compatibilizing agents for mixtures of polyolefins and other types of polymers.

Material Properties of Functional Polyethylenes from Transition-Metal-Catalyzed Ethylene–Polar Monomer Copolymerization

Abstract: Polyethylenes enjoy wide applications due to their many superior properties. The incorporation of some polar functional groups into the otherwise nonpolar polyethylene backbone can significantly improve many important properties and further broaden their applications. During the past few decades, many catalyst systems have been demonstrated with the capabilities of copolymerizing ethylene with polar monomers. As a result, numerous polar functionalized polyethylenes have been prepared bearing various polar groups. However, the studies into material properties of functional polyethylenes from transition-metal-catalyzed ethylene–polar monomer copolymerization have not received much attention until recently. After some brief discussions of selected examples of potent catalysts and suitable polar monomers, this Perspective summarizes some recent advances in the improvements in surface and compatibilities properties (hydrophilicity, adhesion, dyeability, and compatibility with other types of polymers) induced through polar group incorporation as well as some custom-made properties such as elastic, flame-retardant, antibacterial, antioxidant, cross-linking, self-healing, light response, dynamic cross-linking, and photodegradation properties.

Boron clusters as broadband membrane carriers

Abstract: The membrane translocation of hydrophilic substances constitutes a challenge for their application as therapeutic compounds and labelling probes1-4. To remedy this, charged amphiphilic molecules have been classically used as carriers3,5. However, such amphiphilic carriers may cause aggregation and non-specific membrane lysis6,7. Here we show that globular dodecaborate clusters, and prominently B12Br122-, can function as anionic inorganic membrane carriers for a broad range of hydrophilic cargo molecules (with molecular mass of 146-4,500 Da). We show that cationic and neutral peptides, amino acids, neurotransmitters, vitamins, antibiotics and drugs can be carried across liposomal membranes. Mechanistic transport studies reveal that the carrier activity is related to the superchaotropic nature of these cluster anions8-12. We demonstrate that B12Br122- affects cytosolic uptake of different small bioactive molecules, including the antineoplastic monomethyl auristatin F, the proteolysis targeting chimera dBET1 and the phalloidin toxin, which has been successfully delivered in living cells for cytoskeleton labelling. We anticipate the broad and distinct delivery spectrum of our superchaotropic carriers to be the starting point of conceptually distinct cell-biological, neurobiological, physiological and pharmaceutical studies.

Redesigned Hybrid Nylons with Optical Clarity and Chemical Recyclability.

Abstract: Aliphatic polyamides, or nylons, are typically highly crystalline and thermally robust polymers used in high-performance applications. Nylon 6, a high-ceiling-temperature (HCT) polyamide from ε-caprolactam, lacks expedient chemical recyclability, while low-ceiling temperature (LCT) nylon 4 from pyrrolidone exhibits complete chemical recyclability, but it is thermally unstable and not melt-processable. Here, we introduce a hybrid nylon, nylon 4/6, based on a bicyclic lactam composed of both HCT ε-caprolactam and LCT pyrrolidone motifs in a hybridized offspring structure. Hybrid nylon 4/6 overcomes trade-offs in (de)polymerizability and performance properties of the parent nylons, exhibiting both excellent polymerization and facile depolymerization characteristics. This stereoregular polyamide forms nanocrystalline domains, allowing optical clarity and high thermal stability, however, without displaying a melting transition before decomposition. Of a series of statistical copolymers comprising nylon 4/6 and nylon 4, a 50/50 copolymer achieves the greatest synergy in both reactivity and polymer properties of each homopolymer, offering an amorphous nylon with favorable properties, including optical clarity, a high glass transition temperature, melt processability, and full chemical recyclability.

Aliphatic Polyesters with White-Light Clusteroluminescence.

Abstract: Single-molecule white-light emission (SMWLE) has many advantages in practical applications; however, the fabrication of SMWLE from nonconjugated luminescent polymers, namely, clusteroluminogens (CLgens), is still a big challenge. Herein, the first example of linear nonconjugated polyesters with SMWLE is reported. Twenty-four kinds of nonconjugated aliphatic polyesters with tunable clusteroluminescence (CL) colors and efficiency were synthesized by the copolymerization of six epoxides and four anhydrides. Experimental and calculation results prove that, at the primary structure level, the balance of structural flexibility and rigidity via adjusting the side-chain length significantly enhances the efficiency of CL without wavelength change. However, altering the chemical structures of the monomer from succinic anhydride to trans-maleic anhydride (MA), cis-MA, and citraconic anhydride (CA), secondary structures of these polyesters change from helix to straight and folding sheet accompanied by gradually red-shifted CL from 460 to 570 nm due to the increase in through-space n-π* interactions, as demonstrated by the computational and experimental results. Then, pure SMWLE with CIE coordination (0.30, 0.32) based on overlapped short-wavelength and long-wavelength CL is achieved in CA-based polyesters. This work not only provides further insights into the emission mechanism of CL but also provides a new strategy to manipulate the properties of CL by regulating the hierarchical structures of CLgens.

Highly adhesive and dual-crosslinking hydrogel via one-pot self-initiated polymerization for efficient antibacterial, antifouling and full-thickness wound healing

Abstract: A multifunctional hydrogel dressing system with high adhesion and dual-crosslinking for efficient antibacterial, antifouling and full-thickness wound healing is designed, synthesized via one-pot self-initiated polymerization and evaluated. Arginine-modified chitosan-oligosaccharide (COS-Arg)-doped hydrogel system is prepared by exploiting the spontaneous radical polymerization of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA). SBMA is cross-linked with methacrylamide dopamine (DMA) and methacrylatoethyl trimethyl ammonium chloride (DMC) through covalent bonding to form the hydrogel framework at room temperature under nitrogen atmosphere. The catechol groups on DMA, zwitterionic SBMA and the quaternary ammonium groups in the system endows the functional hydrogel system with good strength, excellent adhesion to the wound and a tight fit even under motion. The hemolytic activity, CCK-8, cell scratching and live/dead staining assays confirm the excellent cytocompatibility of the multifunctional hydrogel. Antibacterial tests demonstrate the excellent antibacterial activity of the hydrogel against E. coli and S. aureus. Animal studies show that hydrogels are effective in maintaining a moist microenvironment at the wound site, promoting the production of vascular endothelial growth factor (VEGF) and hydroxyproline and reducing the formation of tumor necrosis factor-α (TNF-α), thus effectively accelerating wound healing in vivo, which idicating the satisfactory effect of the dual-crosslinking multifunctional hydrogel dressings for wound healing.

Combinatorial Polyacrylamide Hydrogels for Preventing Biofouling on Implantable Biosensors

Abstract: Biofouling on the surface of implanted medical devices and biosensors severely hinders device functionality and drastically shortens device lifetime. Poly(ethylene glycol) and zwitterionic polymers are currently considered "gold-standard" device coatings to reduce biofouling. To discover novel anti-biofouling materials, a combinatorial library of polyacrylamide-based copolymer hydrogels is created, and their ability is screened to prevent fouling from serum and platelet-rich plasma in a high-throughput parallel assay. It is found that certain nonintuitive copolymer compositions exhibit superior anti-biofouling properties over current gold-standard materials, and machine learning is used to identify key molecular features underpinning their performance. For validation, the surfaces of electrochemical biosensors are coated with hydrogels and their anti-biofouling performance in vitro and in vivo in rodent models is evaluated. The copolymer hydrogels preserve device function and enable continuous measurements of a small-molecule drug in vivo better than gold-standard coatings. The novel methodology described enables the discovery of anti-biofouling materials that can extend the lifetime of real-time in vivo sensing devices.

Random Terpolymer Enabling High‐Efficiency Organic Solar Cells Processed by Nonhalogenated Solvent with a Low Nonradiative Energy Loss

Abstract: Three terpolymer donors (PL1, PL2, and PL3) employing repeating units of two popular photovoltaic polymers PM6 and D18 are synthesized by random copolymerization. The terpolymers can reduce the regio‐regularity of the polymer backbones and endow them with much‐enhanced solubility in nonhalogenated solvents such as o‐xylene. Furthermore, along with the appearance of temperature‐dependent aggregation behavior, indicating the adaptability for fabricating organic solar cells (OSCs) by eco‐friendly solvent processing. Among them, PL1‐based OSCs display higher and more balanced hole and electron mobilities, longer charge separation exciton lifetime, and better exciton dissociation and charge collection capabilities than the parent polymers (PM6 and D18) based ones. A power conversion efficiency of 18.14% with a very low energy loss is achieved based on terpolymer PL1, which is much higher than that of PM6 (15.16%) and D18 (16.18%). The result provides an effective way to realize high‐performance nonhalogenated processing polymer donor materials.

Intrinsically Breathable and Flexible NO2 Gas Sensors Produced by Laser Direct Writing of Self-Assembled Block Copolymers.

Abstract: The surge in air pollution and respiratory diseases across the globe has spurred significant interest in the development of flexible gas sensors prepared by low-cost and scalable fabrication methods. However, the limited breathability in the commonly used substrate materials reduces the exchange of air and moisture to result in irritation and a low level of comfort. This study presents the design and demonstration of a breathable, flexible, and highly sensitive NO2 gas sensor based on the silver (Ag)-decorated laser-induced graphene (LIG) foam. The scalable laser direct writing transforms the self-assembled block copolymer and resin mixture with different mass ratios into highly porous LIG with varying pore sizes. Decoration of Ag nanoparticles on the porous LIG further increases the specific surface area and conductivity to result in a highly sensitive and selective composite to detect nitrogen oxides. The as-fabricated Ag/LIG gas sensor on a flexible polyethylene substrate exhibits a large response of -12‰, a fast response/recovery of 40/291 s, and a low detection limit of a few parts per billion at room temperature. Integrating the Ag/LIG composite on diverse fabric substrates further results in breathable gas sensors and intelligent clothing, which allows permeation of air and moisture to provide long-term practical use with an improved level of comfort.

An efficient polymer acceptor <i>via</i> a random polymerization strategy enables all-polymer solar cells with efficiency exceeding 17%

Abstract: A series of polymer acceptors have been synthesized. The optical and electronic properties of the copolymers can be well-tuned via a random copolymerization strategy. The best-performing PY-82-based binary device produces a record-high efficiency of 17.15%.

Copolymerization of Sulfur Chains with Vinyl Functionalized Metal−Organic Framework for Accelerating Redox Kinetics in Lithium−Sulfur Batteries

Abstract: Lithium−sulfur batteries (LSBs) are regarded as one of the most promising candidates for energy storage devices. However, the severe shuttling effect of soluble polysulfides (PSs) limits its further application. Metal−organic frameworks (MOFs) have emerged as a new kind of sulfur host for their talents in confining and trapping PSs. However, the shuttle effect has not been fully stressed as a significant drawback for most MOFs that leads to sluggish redox kinetics, resulting in low specific capacity and short lifetime, especially at high sulfur loading. In this work, a MOF‐sulfur copolymer (CNT@UiO‐66‐V‐S) is elaborated by copolymerization of sulfur with vinyl functionalized MOFs. Systematic electrochemical experiments and in situ Raman spectroscopy analysis indicate that the cathode exhibits a radical reaction mechanism and can accelerates LiPSs conversion. The CNT@UiO‐66‐V‐S cathode delivers over 100% improved discharge capacity and lowers decay rate at both low and high (5.6 mg cm–2) sulfur loadings compared to the physically mixed MOF/S cathode. The strategy of MOF‐sulfur copolymerization provides a new solution for promoting reaction kinetics and tackling the shuttle effect, and is expected to inspire the design of advanced sulfur hosts applied for high‐performance LSBs.

Performance descriptors of nanostructured metal catalysts for acetylene hydrochlorination

Abstract: Controlling the precise atomic architecture of supported metals is central to optimizing their catalytic performance, as recently exemplified for nanostructured platinum and ruthenium systems in acetylene hydrochlorination, a key process for vinyl chloride production. This opens the possibility of building on historically established activity correlations. In this study, we derived quantitative activity, selectivity and stability descriptors that account for the metal-dependent speciation and host effects observed in acetylene hydrochlorination. To achieve this, we generated a platform of Au, Pt, Ru, Ir, Rh and Pd single atoms and nanoparticles supported on different types of carbon and assessed their evolution during synthesis and under the relevant reaction conditions. Combining kinetic, transient and chemisorption analyses with modelling, we identified the acetylene adsorption energy as a speciation-sensitive activity descriptor, further determining catalyst selectivity with respect to coke formation. The stability of the different nanostructures is governed by the interplay between single atom-support interactions and chlorine affinity, promoting metal redispersion or agglomeration, respectively.

Amphiphilic Block Copolymers: Their Structures, and Self-Assembly to Polymeric Micelles and Polymersomes as Drug Delivery Vehicles

Abstract: Self-assembly of amphiphilic block copolymers display a multiplicity of nanoscale periodic patterns proposed as a dominant tool for the ‘bottom-up’ fabrication of nanomaterials with different levels of ordering. The present review article focuses on the recent updates to the self-association of amphiphilic block copolymers in aqueous media into varied core-shell morphologies. We briefly describe the block copolymers, their types, microdomain formation in bulk and micellization in selective solvents. We also discuss the characteristic features of block copolymers nanoaggregates viz., polymer micelles (PMs) and polymersomes. Amphiphilic block copolymers (with a variety of hydrophobic blocks and hydrophilic blocks; often polyethylene oxide) self-assemble in water to micelles/niosomes similar to conventional nonionic surfactants with high drug loading capacity. Double hydrophilic block copolymers (DHBCs) made of neutral block-neutral block or neutral block-charged block can transform one block to become hydrophobic under the influence of a stimulus (physical/chemical/biological), and thus induced amphiphilicity and display self-assembly are discussed. Different kinds of polymer micelles (viz. shell and core-cross-linked, core-shell-corona, schizophrenic, crew cut, Janus) are presented in detail. Updates on polymerization-induced self-assembly (PISA) and crystallization-driven self-assembly (CDSA) are also provided. Polyion complexes (PICs) and polyion complex micelles (PICMs) are discussed. Applications of these block copolymeric micelles and polymersomes as nanocarriers in drug delivery systems are described.

Engineered bioorthogonal POLY-PROTAC nanoparticles for tumour-specific protein degradation and precise cancer therapy

Abstract: PROteolysis TArgeting Chimeras (PROTACs) has been exploited to degrade putative protein targets. However, the antitumor performance of PROTACs is impaired by their insufficient tumour distribution. Herein, we present de novo designed polymeric PROTAC (POLY-PROTAC) nanotherapeutics for tumour-specific protein degradation. The POLY-PROTACs are engineered by covalently grafting small molecular PROTACs onto the backbone of an amphiphilic diblock copolymer via the disulfide bonds. The POLY-PROTACs self-assemble into micellar nanoparticles and sequentially respond to extracellular matrix metalloproteinase-2, intracellular acidic and reductive tumour microenvironment. The POLY-PROTAC NPs are further functionalized with azide groups for bioorthogonal click reaction-amplified PROTAC delivery to the tumour tissue. For proof-of-concept, we demonstrate that tumour-specific BRD4 degradation with the bioorthogonal POLY-PROTAC nanoplatform combine with photodynamic therapy efficiently regress tumour xenografts in a mouse model of MDA-MB-231 breast cancer. This study suggests the potential of the POLY-PROTACs for precise protein degradation and PROTAC-based cancer therapy.

Selective branch formation in ethylene polymerization to access precise ethylene-propylene copolymers

Abstract: Abstract Polyolefins with branches produced by ethylene alone via chain walking are highly desired in industry. Selective branch formation from uncontrolled chain walking is a long-standing challenge to generate exclusively branched polyolefins, however. Here we report such desirable microstructures in ethylene polymerization by using sterically constrained α-diimine nickel(II)/palladium(II) catalysts at 30 °C–90 °C that fall into industrial conditions. Branched polyethylenes with exclusive branch pattern of methyl branches (99%) and notably selective branch distribution of 1,4-Me 2 unit (86%) can be generated. The ultrahigh degree of branching (>200 Me/1000 C) enables the well-defined product to mimic ethylene-propylene copolymers. More interestingly, branch distribution is predictable and computable by using a simple statistical model of p(1-p) n (p: the probability of branch formation). Mechanistic insights into the branch formation including branch pattern and branch distribution by an in-depth density functional theory (DFT) calculation are elucidated.

Cleavable Comonomers for Chemically Recyclable Polystyrene: A General Approach to Vinyl Polymer Circularity.

Abstract: Many common polymers, especially vinyl polymers, are inherently difficult to chemically recycle and are environmentally persistent. The introduction of low levels of cleavable comonomer additives into existing vinyl polymerization processes could facilitate the production of chemically deconstructable and recyclable variants with otherwise equivalent properties. Here, we report thionolactones that serve as cleavable comonomer additives for the chemical deconstruction and recycling of vinyl polymers prepared through free radical polymerization, using polystyrene (PS) as a model example. Deconstructable PS of different molar masses (∼20-300 kDa) bearing varied amounts of statistically incorporated thioester backbone linkages (2.5-55 mol %) can be selectively depolymerized to yield well-defined thiol-terminated fragments (<10 kDa) that are suitable for oxidative repolymerization to generate recycled PS of nearly identical molar mass to the parent material, in good yields (80-95%). A theoretical model is provided to generalize this molar mass memory effect. Notably, the thermomechanical properties of deconstructable PS bearing 2.5 mol % of cleavable linkages and its recycled product are similar to those of virgin PS. The additives were also shown to be effective for deconstruction of a cross-linked styrenic copolymer and deconstruction and repolymerization of a polyacrylate, suggesting that cleavable comonomers may offer a general approach toward circularity of many vinyl (co)polymers.

Organic phosphorescent scintillation from copolymers by X-ray irradiation

Abstract: Abstract Scintillators that exhibit X-ray-excited luminescence have great potential in radiation detection, X-ray imaging, radiotherapy, and non-destructive testing. However, most reported scintillators are limited to inorganic or organic crystal materials, which have some obstacles in repeatability and processability. Here we present a facile strategy to achieve the X-ray-excited organic phosphorescent scintillation from amorphous copolymers through the copolymerization of the bromine-substituted chromophores and acrylic acid. These polymeric scintillators exhibit efficient X-ray responsibility and decent phosphorescent quantum yield up to 51.4% under ambient conditions. The universality of the design principle was further confirmed by a series of copolymers with multi-color radioluminescence ranging from green to orange-red. Moreover, we demonstrated their potential application in X-ray radiography. This finding not only outlines a feasible principle to develop X-ray responsive phosphorescent polymers, but also expands the potential applications of polymer materials with phosphorescence features.

Machine Learning on a Robotic Platform for the Design of Polymer–Protein Hybrids

Abstract: Polymer–protein hybrids are intriguing materials that can bolster protein stability in non-native environments, thereby enhancing their utility in diverse medicinal, commercial, and industrial applications. One stabilization strategy involves designing synthetic random copolymers with compositions attuned to the protein surface, but rational design is complicated by the vast chemical and composition space. Here, a strategy is reported to design protein-stabilizing copolymers based on active machine learning, facilitated by automated material synthesis and characterization platforms. The versatility and robustness of the approach is demonstrated by the successful identification of copolymers that preserve, or even enhance, the activity of three chemically distinct enzymes following exposure to thermal denaturing conditions. Although systematic screening results in mixed success, active learning appropriately identifies unique and effective copolymer chemistries for the stabilization of each enzyme. Overall, this work broadens the capabilities to design fit-for-purpose synthetic copolymers that promote or otherwise manipulate protein activity, with extensions toward the design of robust polymer–protein hybrid materials.

Selective branch formation in ethylene polymerization to access precise ethylene-propylene copolymers

Abstract: Abstract Polyolefins with branches produced by ethylene alone via chain walking are highly desired in industry. Selective branch formation from uncontrolled chain walking is a long-standing challenge to generate exclusively branched polyolefins, however. Here we report such desirable microstructures in ethylene polymerization by using sterically constrained α-diimine nickel(II)/palladium(II) catalysts at 30 °C–90 °C that fall into industrial conditions. Branched polyethylenes with exclusive branch pattern of methyl branches (99%) and notably selective branch distribution of 1,4-Me 2 unit (86%) can be generated. The ultrahigh degree of branching (>200 Me/1000 C) enables the well-defined product to mimic ethylene-propylene copolymers. More interestingly, branch distribution is predictable and computable by using a simple statistical model of p(1-p) n (p: the probability of branch formation). Mechanistic insights into the branch formation including branch pattern and branch distribution by an in-depth density functional theory (DFT) calculation are elucidated.