Comb-like Copolymers Research Articles

Inertial migration of cylindrical micelles formed by comb-like copolymer in Poiseuille flow

By combining the lattice Boltzmann model of fluid flow with the molecular dynamics model of copolymers, we investigate the inertial migration of cylindrical micelles, which is obtained by controlling the length ratios of hydrophilic and hydrophobic segments in a comb-like copolymer. Our results demonstrate that cylindrical micelles gradually deviate from the center of the nanochannel with increasing Reynolds number (Re). For the same Re, the larger the cylindrical micelle is, the closer it is to the center of the nanochannel. Importantly, we find that the change in the equilibrium position is particularly pronounced at Re less than 0.1, while the trend becomes smoother at Re greater than 0.1, which is because of the transition of micelles from cylindrical to disk-like shapes when Re is smaller than 0.1, and does not change as Re further increases. This work provides an understanding of cylindrical micelles' inertial migration, particularly in identifying the effect of morphological changes on the equilibrium position, which could lead to significant advancements in the inertial migration of polymer micelles.

Self-assembly of amphiphilic asymmetric comb-like copolymers with responsive rigid side chains.

Amphiphilic asymmetric comb-like copolymers (AACCs) exhibit distinct self-assembly behaviours due to their unique architecture. However, the synthetic difficulties of well-defined AACCs have prohibited a systematic understanding of the architecture-morphology relationship. In this work, we conducted dissipative particle dynamics simulations to investigate the self-assembly behaviours of AACCs with responsive rigid side chains in selective solvents. The effects of side chain length, number of branches, and spacers on the morphology of aggregates were investigated by mapping out morphology diagrams. Besides, the numbers and surface areas of aggregates clearly depicted the morphological transitions during the self-assembly process. Moreover, the rod-to-coil conformation transitions were simulated to explore the stimuli-responsive behaviour of the AACCs with responsive rigid side chains by adjusting the bond angle parameter of the rigid chains. The results indicated that without the support of the rigid chains, the assembly structure collapsed, leading to the tube-to-channelized micelles and one-compartment-to-multicompartment vesicle morphology transformations. The simulation results are consistent with earlier experimental results, which can provide theoretical guidance for assembly toward desired nanostructures.

Homology Violation in a Series of Amphiphilic Comb-Like Statistical Copolymers of N-Methyl-N-vinylacetamide and N-Methyl-N-vinylamine with Moderate Density of Grafting of Side Dodecyl Groups

Homology Violation in a Series of Amphiphilic Comb-Like Statistical Copolymers of N-Methyl-N-vinylacetamide and N-Methyl-N-vinylamine with Moderate Density of Grafting of Side Dodecyl Groups

Homology Violation in a Series of Amphiphilic Comb-Like Statistical Copolymers of N-Methyl-N-vinylacetamide and N-Methyl-N-vinylamine with Moderate Density of Grafting of Side Dodecyl Groups

A series of water-soluble comb-like copolymers of N-methyl-N-vinylacetamide and N-methyl-N-vinylamine (MVAA‒со‒MVA) bearing hydrophobic dodecyl side groups С12Н25 has been investigated by means of molecular hydrodynamics (viscometry, translational diffusion, and analytical ultracentrifugation) in dilute solutions in 0.1 M NaCl, under conditions of suppression of the polyelectrolyte effects. The issues of homology of these amphiphilic copolymers have been considered. The viscometry data plotted as lnηr as function of c[η] have allowed to distinguish between macromolecules of the copolymers according to their hydrophobicity. Positive values of the second derivative B2 determined from the initial parts of these curves have served as a measure of hydrophobicity of the amphiphilic copolymers. The noticeable differences in the B2 values for different copolymers have shown that they do not form true homologous series. For the quasi-homologous series of the MVAA–со–MVAC12H25·HI copolymers with close values of B2, the Kuhn–Mark–Houwink–Sakurada relationships have been obtained and the equilibrium rigidity of the chains has been assessed using the modified Gray–Bloomfield–Hearst equation.

Construction and performance of PVDF-HFP-matrix comb-like gel copolymer electrolyte for high-performance quasi-solid-state lithium-metal batteries

Rechargeable lithium metal batteries (LMBs) have encountered bottlenecks in energy density, durability, and safety issues. Designing functional polymer electrolytes has been considered as an effective way to develop high-performance of LMBs. In this study, PVDF-HFP-matrix polymeric electrolytes blended with copolymer P(MMA-co-PEGMEMA) (PPxPy) via a simple one-pot free-radical polymerization are successfully designed and prepared. It has been found that the PPxPy electrolytes can construct different comb-like networks via systematically tuning monomer ratios. The tailored PP5P5 gel electrolyte exhibited high ionic conductivity of 0.74 × 10−3 S cm−1 at room temperature (RT), an enlarged electrochemical window up to 4.77 V, high lithium-ion transference number tLi+ of 0.65, and good mechanical property with Yang's modulus up to 131 MPa. Benefited from these good properties, the Li||LiFePO4 batteries assembled with PP5P5 gel electrolyte achieved an exceptional discharge capacity of 152 mAh g−1 with nearly 100 % Coulombic efficiency after 150 cycles at 1C. Furthermore, the Li|PP5P5|NCM811 cell exhibits excellent reversible specific capacity of 188 mAh g−1 at 0.1C. Consequently, it can be anticipated the as-prepared functional polymer structure to provide a reliable method for the preparation of polymer electrolytes in quasi-solid-state batteries with high-energy-density.

Polymorphism of self-assembled colloidal nanostructures of comblike and bottlebrush block copolymers

Polymorphism of self-assembled colloidal nanostructures of comblike and bottlebrush block copolymers

Conformation of an Amphiphilic Comb-like Copolymer in a Selective Solvent

Conformation of an Amphiphilic Comb-like Copolymer in a Selective Solvent

Toughening of epoxy thermosets by self-assembled nanostructures of amphiphilic comb-like random copolymers.

Amphiphilic comb-like random copolymers synthesized from poly(ethylene glycol) methyl ether methacrylate (PEGMMA) and stearyl methacrylate (SMA) with PEGMMA contents ranging between 30 wt% and 25 wt% were demonstrated to self-assemble into various well-defined nanostructures, including spherical micelles, wormlike micelles, and vesicle-like nanodomains, in anhydride-cured epoxy thermosets. In addition, the polymer blends of the comb-like random copolymer and poly(stearyl methacrylate) were prepared and incorporated into epoxy thermosets to form irregularly shaped nanodomains. Our research findings indicate that both the comb-like random copolymers and polymer blends are suitable as toughening modifiers for epoxy. When added at a concentration of 5 wt%, both types of modifiers lead to substantial improvements in the tensile toughness (>289%) and fracture toughness of epoxy thermosets, with minor reductions in their elastic modulus (<16%) and glass transition temperature (<6.1 °C). The fracture toughness evaluated in terms of the critical stress intensity factor (KIC) and the strain energy release rate (GIC) increased by more than 67% and 131% for the modified epoxy thermosets containing comb-like random copolymers.

Flow-driven translocation of comb-like copolymer micelles through a nanochannel.

Using hybrid lattice-Boltzmann molecular dynamics simulations, we investigate the flow-driven translocation of comb-like copolymer micelles through a nanochannel, in particular, making a detailed comparison with micelles formed by the corresponding diblock copolymers. Our results demonstrate that the critical flow flux of micelles formed by the comb-like copolymers is higher than that of micelles formed by the corresponding diblock copolymers, which is more pronounced with increasing side chain lengths or grafting densities, as evidenced by the free energy computed by self-consistent field theory. Our work indicates that the impact of chain topology on the stability of micelles, especially with the same size, can be well characterized using the critical flow fluxes, which provides a theoretical basis for designing self-assembling micelles for various applications.

Synthesis of comb-like copolymers based on alkyl fumarates and their application as pour-point depressants for akshabulak crude oil

Paraffin deposition causes numerous operational issues during the handling of waxy crude oil, and treatment with comb-structured polymeric additives can mitigate this problem. Copolymers based on dialkyl fumarates (DRFs) with long aliphatic side chains have shown potential for this purpose. However, there is no all-purpose agent that is efficient for all types of crude oil. This study investigates the effects of different copolymer characteristics, such as composition, molecular weight, and length of pending groups on the rheological behavior of Akshabulak crude oil upon additive treatment. The characteristics were varied by altering the comonomer type, polymerization technique, molar feed ratio of the comonomers, and composition of the DRFs. The fumarates and their copolymers were synthesized, and the products were characterized using Fourier-transform infrared (FTIR) and nuclear magnetic resonance spectroscopy. In addition, other parameters, such as intrinsic viscosity and molecular weight were determined. The efficiency of Akshabulak crude oil treatment with the synthesized copolymers was examined using pour-point measurements, rheoviscometry, and optical microscopy. The results indicated that dibehenyl fumarate–vinyl acetate with a molar feed ratio of 1:1.5 demonstrated good performance as a pour-point depressant.

Covalent Conjugate of Ser-Pro-Cys Tripeptide with PEGylated Comb-Like Polymer as Novel Killer of Human Tumor Cells.

Recently, we detected a previously unknown Ser-Pro-Cys (SPC) tripeptide in the blood serum of multiple sclerosis patients. Its role as a biomarker of the autoimmune disease was suggested, although its origin and real biological activity remained unclear. Here, we created a biocompatible PEGylated comb-like polymer that was used as a platform for covalent immobilization of the SPC, which provided a possibility to explore the biological activity of this tripeptide. This macromolecular conjugate was synthesized via a reaction of the terminal epoxide group of the biocompatible copolymer of dimethyl maleate (DMM) and polyethylene glycol methyl ether methacrylate (PEGMA) with the amino group of the SPC tripeptide. Unexpectedly, the resulting conjugate containing SPC demonstrated anticancer activity in vitro. It possessed pro-apoptotic action toward human tumor cells, while there was no cytotoxic effect of that conjugate toward normal lymphocytes of human peripheral blood. The detected biological effects of the created conjugate inspired us to carry out a thorough study of structural and colloidal-chemical characteristics of this surface-active copolymer containing side PEG chains and a terminal nontoxic synthetic fragment. The copolymer composition, in particular, the content of the peptide fragment, was determined via elemental analysis and NMR spectroscopy. At CMC, it formed polymeric micelle-like structures with a hydrodynamic diameter of 180 ± 60 nm. The conjugation of the peptide fragment to the initial comb-like copolymer caused a change of zeta-potential of the formed micelle-like structures from -0.15 to 0.32 mV. Additional structural modification of the created polymeric nanoplatform was performed via attachment of fluorescein isothiocianate (FITC) dye that permitted monitoring of the behavior of the bioactive SPC-functionalized conjugate in the treated tumor cells. Its penetration into those cells and localization in their cytoplasm were revealed. The principal novelty of this study consists in finding that covalent conjugation of two nontoxic compounds-SPC tripeptide and comb-like PEGylated polymer-led to an unexpected synergy which appeared in the distinct cytotoxic action of the macromolecular complex toward human tumor cells. A potential role of peculiarities of the colloidal-chemical properties of the novel conjugate in its cytotoxic effect are discussed. Thus, synthesized comb-like PEGylated polymers can provide a prospective nanoplatform for drug delivery in anticancer chemotherapy.

A novel higher fatty acid-based polymeric cold flow improver with remarkable effects for biodiesel - diesel blends

In order to develop renewable resources of environment-friendly for the preparation of cold flow improvers for diesel-biodiesel blends, a novel comb-like copolymers were synthesized from higher fatty acids, para (p)-anisic acid, and glycidyl methacrylate. The effects of copolymers on cold flow properties and crystallization behaviors of biodiesel-diesel blends were evaluated and analyzed. This research pointed out that the higher fatty acids as the copolymer branch chain increased the matching ability with paraffin and higher fatty acid methyl esters (FAMEs), and the anisic acid side chain increased the rigidity of the copolymers. Therefore, the prepared copolymers can preferentially precipitate in the blends and act as the nucleation site so that lead to heterogeneous nucleation of paraffin and higher fatty acid methyl esters (FAMEs), thus improving the low-temperature fluidity. In addition, the copolymers exhibited satisfactory performance on reducing cloud point (CP), cold filter plugging point (CFPP), and pour point (PP), which were reduced respectively by 2, 8, and 10 °C for B10 (10 vol%. biodiesel +90 vol%. diesel); 2, 13, and 8 °C for B20 (20 vol%. biodiesel +80 vol%. diesel) and 2, 11, and 7 °C for B30 (30 vol%. biodiesel +70 vol%. diesel) at the addition of 1000 mg / kg.

Functional Poly(ε-caprolactone)/Poly(ethylene glycol) Copolymers with Complex Topologies for Doxorubicin Delivery to a Proteinase-Rich Tumor Environment

Doxorubicin (DOX)-loaded polymer nanoparticles based on poly(ethylene glycol)-poly(ε-caprolactone) copolymers with a complex macromolecular topology are proposed to tackle the matrix metalloproteinase (MMP)-rich tumor environment. Linear, 4-arm comb-like copolymers and 4-arm brush block copolymers were synthesized through a combination of ring opening polymerization and atom transfer radical polymerization, in order to control the molar mass distribution, the arm/brush architecture, as well as the final size and DOX loading of self-assembled nanoparticles obtained by nanoprecipitation. The optimized nanocarriers were conjugated with penetrating low molecular weight protamine peptides coupled to a polyanionic inhibitory domain cleavable by matrix metalloproteinase-2 (MMP2). DOX-loaded, MMP2-activable nanocarriers were evaluated in the context of glioblastoma (GBM), a brain tumor characterized by remarkable and relevant MMP2 expression. Uptake and cytotoxicity in patient-derived GBM cells correlated with the level of MMP2 enzymatic activity in a dose- and time-dependent manner. No effects were observed in nontumoral endothelial cells that do not express MMP2. Results demonstrated that, by tuning polymer topology and peptide sequence, nanoparticle self-assembly, DOX encapsulation, and delivery can be optimized for the development of an advanced treatment for MMP2-overexpressing tumors.

Ferroelectric electroluminescent comb copolymer for single-material self-powered displays

Ferroelectric polymers have recently been applied in human-connected electronics as pressure (touch)-sensing materials to develop high-performance electronic skin and tactile sensing memory. Here, we report an organic synthetic route for developing a polymer possessing both ferroelectric and electroluminescent properties from which a self-powered pliable display can be readily implemented. The synthetic route involves reversible addition-fragmentation transfer-mediated graft copolymerization of poly(vinylidene fluoride) (PVDF) onto a polyfluorene (PFO) backbone, which results in a comb-like copolymer architecture composed of ferroelectric side chains (PVDFs) tethered to a light-emitting main chain (PFO). The resultant thin comb copolymer film, equipped with hardly integrable three natures (i.e., ferro- and piezoelectricity, luminescence, pliability), exhibits excellent light emission under alternating current and self-powering attributes upon mechanical deformation. This multifunctional polymer, where various properties including ferroelectricity and electroluminescence are imparted in molecular-level precision, envisions its use in a wide range of fields such as emerging self-powered interactive displays. • Synthesis of comb copolymer consisting of PFO backbone grafted with PVDF polymer • Copolymer with synchronous ferroelectric and electroluminescent properties • Development of polymer light-emitting diode with self-powered piezoelectricity Kim et al. demonstrate a ferroelectric-polymer-grafted electroluminescent comb copolymer that simultaneously exhibits ferroelectricity, photoluminescence, and electroluminescence. The ferroelectric and light-emitting film can be readily used in flexible polymer light-emitting diodes and piezoelectric nanogenerators via solution processing, making it a promising candidate for the development of wearable human-interactive self-powered photoelectronics.

Crystalline lamellar films with honeycomb structure from comb-like polymers of poly(2-long-alkyl-2-oxazoline)s

Comb-like copolymers are usually structured by grafting polymeric side chains onto main polymer chain. There are few reports of comb-on-comb polymers in which dense secondary side chains are grafted onto primary side chain. In this work, we synthesized comb polymers with grafted-on-graft side chains (c-PEI-g-Acyl) via an effective acylation reaction of comb polymers possessing polyethyleneimine (PEI) side chain with long-alkyl acyl chlorides. For comparison, we also synthesized homopolymers l-PEI-g-Acyls via reaction of linear PEI with long-alkyl acyl chlorides. Then, we investigated their crystalline feature in the film formation by XRD, DSC and SEM, and found that the polymers tend to form hexagonal lamella structures with bilayer alkyl spacing. The comb polymers c-PEI-g-Acyls and linear polymers l-PEI-g-Acyls were used in preparation of honeycomb film by the “breath-figure” process by dropping chloroform solution of the polymers on substrate. Different to many honeycomb polymeric films which are supported by amorphous phase, interestingly, our polymers easily afford honeycomb films which are supported by crystalline lamellae frames under higher humidity condition. It was found that the comb polymers of c-PEI-g-Acyls with longer PEI primary side chain and long alkyl secondary side chain have advantages in producing honeycomb film than linear polymers of l-PEI-g-Acys.

Influence of Pentaerythritol Tetraacrylate Crosslinker on Polycarboxylate Superplasticizer Performance in Cementitious System.

In this work, a crosslinked polycarboxylate superplasticizer (crosslinked-PC) was synthesized via the free radical polymerization reaction. Pentaerythritol tetraacrylate (PETA) was used as the crosslinked agent. A comparative comb-like polycarboxylate superplasticizer (comb-like-PC) was prepared under the same reaction conditions. The dispersion retention capacity, dispersion capability, hydration characteristics of the cement paste and setting time were investigated in detail. At the dosage of 0.6% bwoc, the fluidity of the cement/crosslinked-PC paste was about 340 mm, which was 40~50 mm larger than the cement/comb-like-PC paste. The dispersion retention capacity of the cement/crosslinked-PC paste was observed to be much superior due to higher adsorbed amounts on the cement particles. Moreover, the cement/crosslinked-PC paste exhibited the initial and final setting durations of 196 and 356 min, respectively, which indicated an enhancement of 18 and 68 min compared to the cement/comb-like paste. The crosslinked copolymers exhibit a stronger retardation effect than the comb-like copolymers due to their enhanced adsorbed amounts and stronger steric hindrance effect. This is further illustrated by the characterization of the hydration process and hydration products. It can be concluded that it is feasible to improve the dispersive capacity and the dispersion retention capacity of PC by changing the molecule structure from comb-like to slightly crosslinked.

Liquid-liquid phase separated microdomains of an amphiphilic graft copolymer in a surfactant-rich medium

The liquid-liquid phase separation (LLPS) of amphiphilic thermoresponsive copolymers can lead to the formation of micron-sized domains, known as simple coacervates. Due to their potential to confine active principles, these copolymer-rich droplets have gained interest as encapsulating agents. Understanding and controlling the conditions inducing this LLPS is therefore essential for applicative purposes and requires thorough fundamental studies on self-coacervation. In this work, we investigate the LLPS of a comb-like graft copolymer (PEG-g-PVAc) consisting of a poly(ethylene glycol) backbone (6 kDa) with ∼2–3 grafted poly(vinyl acetate) chains, and a PEG/PVAc weight ratio of 40/60. Specifically, we report the effect of various water-soluble additives on its phase separation behavior. Kosmotropes and non-ionic surfactants were found to decrease the phase separation temperature of the copolymer, while chaotropes and, above all, ionic surfactants increased it. We then focus on the phase behavior of PEG-g-PVAc in the presence of sodium citrate and a C14-15 E7 non-ionic surfactant (N45-7), defining the compositional range for the generation of LLPS microdomains at room temperature and monitoring their formation with fluorescence confocal microscopy. Finally, we determine the composition of the microdomains through confocal Raman microscopy, demonstrating the presence of PEG-g-PVAc, N45-7, and water. These results expand our knowledge on polymeric self-coacervation, clarifying the optimal conditions and composition needed to obtain LLPS microdomains with encapsulation potential at room temperature in surfactant-rich formulations.

A mixed matrix membrane for enhanced CO2/N2 separation via aligning hierarchical porous zeolite with a polyethersulfone based comb-like polymer

BackgroundMixed matrix membranes (MMM)s for CO2/N2 separation still suffer from interfacial defects. MethodTo address this, a series of MMMs were prepared using polyethersulfone-g-poly (ethylene glycol) (PES-g-PEG) comb-like copolymer to tune the interfacial interaction with a pillared MFI (PMFI) zeolite nanosheets, which has a hierarchical porous structure to improve permeance. The composite membranes were examined by SEM, EDX and XRD. The dependence of gas permeabilities, diffusion and solubility coefficients of CO2 and N2 were determined by the time-lag method. ResultsThe increase in PMFI zeolite loading led to an increase in the permeability coefficient of CO2, which is mainly caused by the increase in CO2 diffusion coefficient. The CO2/N2 gas separation was optimized at a loading of 20wt% PMFI zeolite, which produces a composite membrane with a CO2 permeability of 66.9 Barrer and an ideal permeability selectivity coefficient of 9.6.

Photonic Particles Made by the Confined Self-Assembly of a Supramolecular Comb-Like Block Copolymer.

Approaches that enable the preparation of robust polymeric photonic particles are of interest for the development of nonfading and highly reflective pigments for applications such as paints and display technologies. Here, the preparation of photonic particles that display structural color in both, aqueous suspension and the dry solid state is reported. This is achieved by exploiting the confined self-assembly of a supramolecular comb-like block copolymer (BCP) that microphase separates into a well-ordered lamellar morphology with dimensions that promote a photonic bandgap in the visible range. The comb-like BCP is formed by robust ionic interactions between poly(styrene-b-4-vinyl-pyridine) (PS-b-P4VP) BCP and dodecylbenzene sulfonic acid (DBSA), which selectively interacts with P4VP blocks. The components are combined in chloroform, and an aqueous emulsion is prepared. Evaporation of the organic solvent leads to the formation of solid microparticles with an onion-like 3D morphology. These photonic pigments display brilliant colors with reflectance spectra featuring pronounced optical bandgaps across the entire visible wavelength range with a peak reflectivity of 80-90%.

Hierarchical and automatic construction of ultrathin polymer nanoarchitecture with islands of alkyl chains for spontaneous interfacial molecular alignment

Hierarchical ultrathin nanoarchitectures are structurally stable and functionally versatile, which are supramolecular building blocks with a broad range of applications from optoelectronic devices to tunable biosensors. Here, we present a facile and scalable strategy to fabricate an ultrathin polymer nanoarchitecture with islands of alkyl chains for spontaneous interfacial molecular orientation by using the hierarchical and automatic self-assembly of amphiphilic comb-like copolymers. The intriguing self-constructed nanoarchitecture is achieved by facile doping and interfacial self-assembly of amphiphilic poly(dodecyl acrylate)–poly(acrylic acid) comb-like copolymers on hydrophilic indium tin oxide substrate. It is experimentally revealed that an ultrathin and spiky polymer nanoarchitecture with a hydrophobic segment surface formed by hydrophilic and cooperative interactions of amphiphilic copolymers ensures an automatic vertical molecular alignment of liquid crystals during hierarchical self-construction process. Furthermore, this effective approach affords a fast responsive and low-voltage driving polymer nanoarchitecture with an enhanced electro-optical performance compared to common polyimide layer.