Star Polymers Research Articles

An elastomer with ultrahigh strain-induced crystallization

Strain-induced crystallization (SIC) prevalently strengthens, toughens, and enables an elastocaloric effect in elastomers. However, the crystallinity induced by mechanical stretching in common elastomers (e.g., natural rubber) is typically below 20%, and the stretchability plateaus due to trapped entanglements. We report a class of elastomers formed by end-linking and then deswelling star polymers with low defects and no trapped entanglements, which achieve strain-induced crystallinity of up to 50%. The deswollen end-linked star elastomer (DELSE) reaches an ultrahigh stretchability of 12.4 to 33.3, scaling beyond the saturated limit of common elastomers. The DELSE also exhibits a high fracture energy of 4.2 to 4.5 kJ m −2 while maintaining low hysteresis. The heightened SIC and stretchability synergistically promote a high elastocaloric effect with an adiabatic temperature change of 9.3°C.

Functionalization of Violet Phosphorus Quantum Dots with Azo-Containing Star-Shape Polymer for Optically Controllable Memory

Quantum dots (QDs) are emerging as promising candidates for innovative memristive materials, owing to their distinct surface, quantum size, and edge effects. Recent research has focused on tailoring QDs with specific organic molecules to fine-tune charge transfer states between the host and grafted species, as well as enhancing their dispersibility and processability. Violet phosphorus (VP), a newly discovered two-dimensional phosphorus allotrope, offers excellent carrier dynamics, predictable modifiability, and superior oxidation resistance, making it a promising contender in this domain. In this study, we synthesized a rich azobenzene-containing star-shaped polymer diazonium salt (AzoSPD) to functionalize violet phosphorus quantum dots (VPQDs), with the dual objectives of enhancing organic dispersibility and introducing photo-switching capabilities. The synthesized AzoSPD–VPQDs exhibit intramolecular charge transfer characteristics under electrical stimuli of ambient conditions, displaying significant non-volatile rewriteable memory properties and a substantial switching ratio exceeding 2 × 103. Furthermore, the high resistance state (HRS) current can be enhanced by nearly 40 times under 465 nm illumination, enabling optoelectronic information sensing and storage within a single device. This work not only provides insights into enhancing the optoelectronic properties of QDs through functional organic molecular modification but also represents a pioneering exploration of the potential applications of VPQDs in novel memristors.

Effect of Star Topology Versus Linear Polymers on Antifungal Activity and Mammalian Cell Toxicity.

The global increase in invasive fungal infections and the emergence of drug-resistant strains demand the urgent development of novel antifungal drugs. In this context, synthetic polymers with diverse compositions, mimicking natural antimicrobial peptides, have shown promising potential for combating fungal infections. This study investigates how altering polymer end-groups and topology from linear to branched star-like structures affects their efficacy against Candida spp., including clinical isolates. Additionally, the polymers' biocompatibility is accessed with murine embryonic fibroblasts and red blood cells invitro. Notably, a low-molecular weight star polymer outperforms both its linear polymeric counterparts and amphotericin B (AmpB)in terms of an improved therapeutic index and reduced haemolytic activity, despite a higher minimum inhibitory concentration against Candida albicans (C. albicans) SC5314 (16-32µgmL-1 vs 1µgmL-1 for AmpB). These findings demonstrate the potential of synthetic polymers with diverse topologies as promising candidates for antifungal applications.

Influence of Architecture on the Interfacial Properties of Polymers: Linear Chains, Stars, and Microgels.

Surface-active polymers have important applications as effective and responsive emulsifiers, foaming agents, and coatings. In this contribution, we explore the impact of the polymer architecture on the behavior at oil-water interfaces by comparing different poly(N-isopropylacrylamide) (pNIPAM)-based systems, namely, monolayers of linear and star-shaped macromolecules, ultralow cross-linked, regular cross-linked, and hollow microgels. Compression isotherms were determined experimentally as well as by computer simulations. The latter provides information about the conformational changes of the individual macromolecules as well as the interfacial properties of the monolayer, including the surface structure and the density distribution of an ensemble of interacting macromolecules near an interface. Surprisingly, the isotherms of the linear polymer, of the star polymer, and of the ultralow cross-linked microgel have an identical shape that differs from the isotherms of regular and hollow microgels. We introduced the mass fraction of adsorbed polymer, which gives a measure of the polymer segments contributing to the isotherm in relation to the most flexible architecture, i.e., the linear polymer, and allows a comparison of polymers with different architectures. The data demonstrate that increasing the number of cross-links leads to a significantly lower amount of polymer in the proximity of the interface as the increase in cross-linker reduces the deformability or softness of the polymers at the interface. The volume fraction profiles along the normal to the interface are essentially different in the microgel monolayers as compared to those in the linear and star polymer. The profiles through the microgel contact line and their growth upon initial compression are similar to those of the linear chains. Herewith, the profiles through the center of mass practically do not change upon compression. Therefore, the initial growth in the microgel surface pressure reveals the polymer-like behavior and is related to the deformation of the peripheral part of the microgel. Further compression of the microgel monolayer leads to 3D interactions of the microgels within the aqueous side of the interface and soft colloid-like behavior.

De novo designed glycopolymer by precise polymer synthesis

Abstract Synthetic polymers with molecular recognition ability were investigated. Well-defined chemical structures of biopolymers were mimicked by controlled polymerization. In particular, the preparation and molecular recognition of de novo designed glycopolymers were studied. Glycopolymers such as block polymers, star polymers, and microgels were prepared. The designed glycopolymers showed strong molecular recognition against target proteins and viruses.

Effect of amphiphilic polymers on phase separating binary mixtures: A DPD simulation study.

We present the phase separation dynamics of a binary (AB), simple fluid (SF), and amphiphilic polymer (AP) mixture using dissipative particle dynamics simulation at d = 3. We study the effect of different AP topologies, including block copolymers, ring block copolymers (RCP), and miktoarm star polymers, on the evolution morphologies, dynamic scaling functions, and length scale of the AB mixture. Our results demonstrate that the presence of APs leads to significantly different evolution morphologies in SF. However, the deviation from dynamical scaling is prominent, mainly for RCP. Typically, the characteristic length scale for SF follows the power law R(t) ∼ tϕ, where ϕ is the growth exponent. In the presence of high AP, we observe diffusive growth (ϕ → 1/3) at early times, followed by saturation in length scale (ϕ → 0) at late times. The extent of saturation varies with constraints imposed on the APs, such as topology, composition ratio, chain length, and stiffness. At lower composition ratios, the system exhibits inertial hydrodynamic growth (ϕ → 2/3) at asymptotic times without clearly exhibiting the viscous hydrodynamic regime (ϕ → 1) at earlier times in our simulations. Our results firmly establish the existence of hydrodynamic growth regimes in low surfactant-influenced phase separation kinetics of binary fluids and settle the related ambiguity in d = 3 systems.

Swelling of star polymer thin films exposed to supercritical carbon dioxide

AbstractImpact of polymer chain architecture on the swelling of supported single‐layer polymer thin films with thicknesses below 80 nm in the presence of supercritical CO2 (scCO2) is investigated using in‐situ neutron reflectivity (NR) and ex‐situ x‐ray reflectivity (XR). 4‐arm star and 8‐arm star deuterated polystyrene (dPS) having similar total molecular weights are used. NR results revealed that the magnitude of the swelling for star polymers increases proportionally with decreasing dry film thicknesses similar to linear polymers. For film thicknesses above 5Rg, architectural differences have no impact on the swelling behavior. However, below 5Rg as the branching increases from linear to 4‐arm star and to 8‐arm star, swelling decreases due to the presence of a relatively thicker adsorbed layer formed by more branched architectures. Ex‐situ XR measurements verified that star architectures swell less than linear architecture and provided new information about the vitrification of the films through rapid quenching and its relation to the amount of CO2 retention.

Structure and Dynamics of Composites of Star Polymers in a Linear Polymer Matrix

Structure and Dynamics of Composites of Star Polymers in a Linear Polymer Matrix

Benzimidazolium ionic liquid functionalized star-polycaprolactone stationary phase for capillary gas chromatography

In this work, an innovative ionic liquid functionalized star-shaped polymer is synthesized by coupling star-polycaprolactone with benzimidazolium (star-PCL-Bim), and statically coated into a capillary column for gas chromatographic (GC) separations. The fabricated star-PCL-Bim capillary column with moderate-polar nature reveals a high column efficiency of 3598 plates/m for n-dodecane at 120 °C, and advantageous distinguishing ability ( R > 1.5) for 9 aromatic isomer mixtures and 12 cis-/ trans -isomers. Its excellent resolving capacity can be credited to the architecture of star-PCL-Bim, the PCL arms, and π-electron-rich benzimidazolium cations, and it results in a quite different retention behavior of star-PCL-Bim from that of star-PCL and commercial HP-35 columns, with “dual-nature” selectivity in separating a mixture including 29 compounds. These favorable chromatographic characteristics demonstrate the great application potential of this material in GC, and provide a prospective strategy to obtain high-performance stationary phases.

Star polymer soil delivery nanoplatform for applying biological agents in the field to control plant rhizosphere diseases

As the main cause of destructive plant diseases, pathogenic oomycete in plant rhizosphere brings about enormous losses to agricultural production. Although chemical pesticides are still one of the most important prevention and control methods for phytopathogens, the usage of chemical pesticides was limited by the 3R (resistance, residue, and rampant) problem. In the early stage of our research, analysis and comparison of the metabolome of resistance to Phytophthora nicotianae and common strain suggested that naringenin might be a highly efficient potential biogenic antimicrobial agent to prevent and control soil rhizosphere diseases. Unfortunately, the bioactivity and absorption capacity of active ingredients in the environment made it unsuitable for field application; thus, for efficient field application of naringenin, the 24 nm-sized naringenin-loaded nano-star-shaped polymerized (NSPs) were prepared with good loading efficiency 37.3% for naringenin. The soil mobility test indicated that NSPs could effectively reduce the adsorption of active ingredients and enhance the mobility of active ingredients in soil. The bacteriostatic test proved that these NSPs had better antimicrobial activity than the naringenin used alone and could efficiently induce the expression of plant resistance phenylpropanoid compounds. Finally, pot and field experiments showed improved control efficiency of NSPs 41% loaded with naringenin. Transcriptome analysis found that a large number of energy-related genes were downregulated in NSPs nematodes, suggesting that disturbed energy-related genes might lead to the disturbance of energy synthesis and metabolism. Naringenin-loaded nano-carriers were used to prevent and control plant disease-causing pathogens in the rhizosphere, which is of great significance to improve the prevention and control effect and reduce the environmental load of these anti-pathogenic agents.

Oligo (ethylene glycol) side chain engineering: An efficient way for boosting the development of green-solvent processable electrochromic devices

As an effective strategy for improving the performance of optoelectronic polymers, oligo (ethylene glycol) (OEG) side chain engineering has been widely used in optoelectronic materials field. However, the research of its impact on electrochromic (EC) polymers started to be explored in recent years. In this work, the excellent EC properties of the star polymer PTQ-10 (poly[(thiophene)-alt-(6,7-difluoro-2-(2-hexyldecyloxy)quinoxaline)]) were first investigated and proved. Subsequently, a series of novel PTQ-type polymers with OEG side chains (PTQ-OEGs) were successfully synthesized and studied. Compared with PTQ-10, the introduction of OEG side chains can significantly shorten the coloring time (∼82.2 %) and improve the coloration efficiency (∼37.3 %). Notably, the solubility of PTQ-OEGs is greatly enhanced in ideal green solvents (ethanol) via introducing the OEG side chains. Therefore, the EC active layers of PTQ-BTEG can be simply fabricated by its ethanol solution. Based on this feature, an all-green EC device PTQ-BTEG@ECD-3 (from material processing to device preparation) was prepared successfully, which exhibited fast coloring (6.25 s) and bleaching (0.85 s) as well as high coloration efficiency (622.57 cm2 C−1). Hence, we not only reported the relationship between OEGs and EC polymers thoroughly, but also proved the OEG engineering is a practical approach to promote the development of all-green EC devices in the near future.

Structural features and antioxidant behavior of lignin polymers isolated from various woody plants

This article presents results of our study of the structural organization of macromolecules of natural lignins isolated from some coniferous and deciduous plants. The main feature of lignin as a polymer is the polyvariability at all levels of structural organization. The study showed that the studied samples were very individual and differed in the content of functional groups, elemental composition, and structural units of the guaiacyl, syringyl, and p-hydroxyphenyl types. Acacia lignin has the most interesting chemical structure, since p-hydroxyphenyl structures are absent in the macromolecule of this biopolymer. The molecular properties of the acacia and spruce lignins are investigated by the methods of high-speed sedimentation, translational diffusion and viscosimetry. It were determined the molecular weight of fractions, the scaling coefficients of the Mark-Kuhn-Houwink equation, fractal dimension df and the value of the Tsvetkov-Klenin hydrodynamic invariant. Based on the analysis of the hydrodynamic behavior and topological structure of macromolecules, it was concluded that acacia lignin was a star-shaped polymer, and spruce lignin was a randomly branched polymer. The studied lignins have interesting and promising biomedical properties. The main feature of lignins is their high antioxidant activity (AOA), which is comparable with the activity of well-known low molecular weight antioxidants. It was shown that lignins from acacia and walnut wood were characterized by the highest AOA. In addition, lignins have excellent sorption properties against the extremely toxic aflatoxin B1 produced by the so-called "yellow mold"(fungi of the genus Aspergillus flavus). The lignin from walnut wood with the index of irreversible adsorption of AF reaching 68.4% should be considered the most effective.

Discrete Miktoarm Star Block Copolymers with Tailored Molecular Architecture.

Molecular architecture is a critical factor in regulating phase behaviors of the block copolymer and prompting the formation of unconventional nanostructures. This work meticulously designed a library of isomeric miktoarm star polymers with an architectural evolution from the linear-branched block copolymer to the miktoarm star block copolymer and to the star-like block copolymer (i.e., 3AB → 3(AB1)B2 → 3(AB)). All of the polymers have precise chemical composition and uniform chain length, eliminating inherent molecular uncertainties such as chain length distribution or architectural defects. The self-assembly behaviors were systematically studied and compared. Gradually increasing the relative length of the branched B1 block regulates the ratio between the bridge and loop configuration and effectively releases packing frustration in the formation of the spherical or cylindrical structures, leading to a substantial deflection of phase boundaries. Complex structures, such as Frank-Kasper phases, were captured at a surprisingly higher volume fraction. Rationally regulating the molecular architecture offers rich possibilities to tune the packing symmetry of block copolymers.

Cover Picture: Modulating Ligand‐Exchange Dynamics on Metal‐Organic Polyhedra for Reversible Sorting and Hybridization of Miktoarm Star Polymers (Angew. Chem. Int. Ed. 49/2023)

Cover Picture: Modulating Ligand‐Exchange Dynamics on Metal‐Organic Polyhedra for Reversible Sorting and Hybridization of Miktoarm Star Polymers (Angew. Chem. Int. Ed. 49/2023)

Titelbild: Modulating Ligand‐Exchange Dynamics on Metal‐Organic Polyhedra for Reversible Sorting and Hybridization of Miktoarm Star Polymers (Angew. Chem. 49/2023)

Titelbild: Modulating Ligand‐Exchange Dynamics on Metal‐Organic Polyhedra for Reversible Sorting and Hybridization of Miktoarm Star Polymers (Angew. Chem. 49/2023)

Hydrogen-Bonded Polymer Nanomedicine with AIE Characteristic for Intelligent Cancer Therapy.

One of the major goals of biomedical science is to pioneer advanced strategies toward precise and smart medicine. Hydrogen-bonding (H-bonding) assembly incorporated with an aggregation-induced emission (AIE) capability can serve as a powerful tool for developing supramolecular nanomedicine with clear tumor imaging and smart therapeutic performance. We here report a H-bonded polymeric nanoformulation with an AIE characteristic toward smart antitumor therapy. To do so, we first design a structurally novel tetraphenylethylene (TPE)-based H-bonding theranostic prodrug, TPE-(FUA)4, characterized by four chemotherapeutic fluorouracil-1-acetic acid (FUA) moieties arched to the TPE core. A six-arm star-shaped amphiphilic polymer vehicle, P(DAP-co-OEGEA)6, is prepared, bearing hydrophilic and biocompatible POEGEA (poly(oligo (ethylene glycol) ethyl acrylate) segments, along with a hydrophobic and H-bonding PDAP (poly(diaminopyridine acrylamide)) segment. Thanks to the establishment of the DAP/FUA H-bonding association, incorporating the TPE-(FUA)4 prodrug to the P(DAP-co-OEGEA)6 vehicle can yield H-bond cross-linked nanoparticles with interpenetrating networks. For the first time, AIE luminogens are interwoven into a six-arm star-shaped polymer via an intrinsic H-bonding array of the chemotherapeutic agent FUA, thus imposing an effective restriction of TPE molecular rotations. Concomitantly, encapsulated photothermal agent (IR780) via a hydrophobic interaction facilitates the formation of nanoassemblies, TPE-(FUA)4/IR780@P(DAP-co-OEGEA)6, featuring synergistic cancer chemo/photothermal therapy (CT/PTT). Our study can contribute a practical solution to fulfill biomedical requirements with a conductive advance in precision nanomedicine.

Catalytic Living ROMP: Synthesis of Degradable Star Polymers.

Star polymers have attracted considerable attention over the past few years due to their distinctive physical and chemical attributes that are different from conventional linear polymers. Here, we present a one-pot synthesis of narrowly dispersed and degradable homoarm and miktoarm star polymers exploiting the catalytic living ring-opening metathesis polymerization (ROMP) mechanism. Several complex polymeric architectures (such as A3-, A4-, A6-, A2B-, A3B-, and AB2-type star polymers) were synthesized quite straightforwardly by using appropriate vinyl ether chain transfer agents. SEC, 1H NMR, and DOSY NMR spectroscopy were employed to analyze and characterize all of the synthesized polymers. We believe that this sustainable and environmentally friendly synthesis of star polymers could become an important synthetic tool for polymer engineers working on supramolecular, industrial or biomedical applications.

Multi-particle collision dynamics for a coarse-grained model of soft colloids applied to ring polymers.

The simulation of polymer solutions often requires the development of methods that accurately include hydrodynamic interactions. Resolution on the atomistic scale is too computationally expensive to cover mesoscopic time and length scales on which the interesting polymer phenomena are observed. Therefore, coarse-graining methods have to be applied. In this work, the solvent is simulated using the well-established multi-particle collision dynamics scheme, and for the polymer, different coarse-graining methods are employed and compared against the monomer resolved Kremer-Grest model by their resulting diffusion coefficients. This research builds on previous work [Ruiz-Franco et al., J. Chem. Phys. 151, 074902 (2019)], in which star polymers and linear chains in a solvent were simulated and two different coarse-graining methods were developed, in order to increase computational efficiency. The present work extends this approach to ring polymers and seeks to refine one of the authors' proposed model: the penetrable soft colloid model. It was found that both proposed models are not well suited to ring polymers; however, the introduction of a factor to the PSC model delivers satisfying results for the diffusion behavior by regulating the interaction intensity with the solvent.

Investigation of the structure and properties of lignins of some agricultural plants

This paper presents our studies of chemical and topological structure of lignin macromolecules isolated from herbaceous plants of various botanical origins. The elemental, monomeric, and functional composition of biopolymers by 13С-NMR spectroscopy, electron paramagnetic resonance, FTIR spectroscopy and Py-GC/MS spectrometry were determined. The antioxidant properties and determined structural-chemical correlations were evaluated. The results of a study of the topological structure of one of the most promising from a biomedical point of view sample of Rhodiola rosea lignin are presented. For the first time, it is proved that this lignin belongs to the class of star-shaped polymers. The geroprotective properties of Rhodiola rosea lignin were studied, and the fact of increasing lifespan of model animal Drosophila melanogaster flies was established. In the first time the effect of lignin from the stems of oats Avena sativa on the cognitive abilities of laboratory mice was studied. The obtained data indicate an improvement in the activity of the brain and central nervous system of model animals with regular preventive administration of lignin.

Modulating Ligand-Exchange Dynamics on Metal-Organic Polyhedra for Reversible Sorting and Hybridization of Miktoarm Star Polymers.

The precise synthesis of miktoarm star polymers (MSPs) remains one of the great challenges in synthetic chemistry due to the difficulty in locating appropriate structural templates and polymer grafting/growing strategies with high selectivity and efficiency. Herein, ≈2 nm metal-organic polyhedra (MOPs), constructed from the coordination of isophthalic acid (IPA) and Cu2+ , are applied as templates for the precise synthesis of 24-arm MSPs for their unique logarithmic ligand-exchange dynamics. Six different polymers are prepared with IPA as an end group and they further coordinated with Cu2+ to afford the corresponding 24-arm star homo-polymers. MSPs can be obtained by mixing targeted homo-arm star polymers in solutions upon thermal annealing. The compositions of MSPs can be facilely and precisely tuned by the recipe of the star polymer mixtures used. Interestingly, the obtained MSPs can be sorted into homo-arm star polymers through a typical solvent extraction procedure. The hybridization and sorting process can be reversibly conducted through the cycle of thermal annealing and solvent treatment. The complex coordination framework not only opens new avenues for the facile and precise synthesis of MSPs and MOPs with hybrid functionalities, but also provides the capability to design sustainable polymer systems.