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The evaporation-induced deposition pattern of the linear diblock copolymer solution has attracted attention in recent years. Given its critical applications, we study deposition patterns of the linear diblock copolymer solution nanodroplet on a solid surface (the wall) by molecular dynamics simulations. This study focuses on the influence of the nonbonded interaction strength, including the interaction between the wall and polymer blocks (ɛAW and ɛBW), the interaction between the solvent and the wall (ɛSW), and the interaction between polymer blocks (ɛAB). Conditions leading to diverse deposition patterns are explored, including the coffee-ring and the volcano-like structures. The formation of the coffee-ring structure is attributed to receding interfaces, the heterogeneity inside the droplet, and the self-assembly of polymer chains. This study contributes to the establishment of guidelines for designing deposition patterns of the linear diblock copolymer solution nanodroplet, which facilitates practical applications such as inkjet printing. [ABSTRACT FROM AUTHOR]

The phase behavior of binary blends of AB diblock copolymers of compositions f and 1 − f is examined using field-theoretic simulations. Highly asymmetric compositions (i.e., f ≈ 0) behave like homopolymer blends macrophase separating into coexisting A- and B-rich phases as the segregation is increased, whereas more symmetric diblocks (i.e., f ≈ 0.5) microphase separate into an ordered lamellar phase. In self-consistent field theory, these behaviors are separated by a Lifshitz critical point at f = 0.2113. However, its lower critical dimension is believed to be four, which implies that the Lifshitz point should be destroyed by fluctuations. Consistent with this, it is found to transform into a tricritical point. Furthermore, the highly swollen lamellar phase near the mean-field Lifshitz point disorders into a bicontinuous microemulsion (BμE), consisting of large interpenetrating A- and B-rich microdomains. BμE has been previously reported in ternary blends of AB diblock copolymer with its parent A- and B-type homopolymers, but in that system the homopolymers have a tendency to macrophase separate. Our alternative system for creating BμE is free of this macrophase separation. [ABSTRACT FROM AUTHOR]

Field-theoretic simulations are numerical treatments of polymer field theory models that go beyond the mean-field self-consistent field theory level and have successfully captured a range of mesoscopic phenomena. Inherent in molecularly-based field theories is a "sign problem" associated with complex-valued Hamiltonian functionals. One route to field-theoretic simulations utilizes the complex Langevin (CL) method to importance sample complex-valued field configurations to bypass the sign problem. Although CL is exact in principle, it can be difficult to stabilize in strongly fluctuating systems. An alternate approach for blends or block copolymers with two segment species is to make a "partial saddle point approximation" (PSPA) in which the stiff pressure-like field is constrained to its mean-field value, eliminating the sign problem in the remaining field theory, allowing for traditional (real) sampling methods. The consequences of the PSPA are relatively unknown, and direct comparisons between the two methods are limited. Here, we quantitatively compare thermodynamic observables, order-disorder transitions, and periodic domain sizes predicted by the two approaches for a weakly compressible model of AB diblock copolymers. Using Gaussian fluctuation analysis, we validate our simulation observations, finding that the PSPA incorrectly captures trends in fluctuation corrections to certain thermodynamic observables, microdomain spacing, and location of order-disorder transitions. For incompressible models with contact interactions, we find similar discrepancies between the predictions of CL and PSPA, but these can be minimized by regularization procedures such as Morse calibration. These findings mandate caution in applying the PSPA to broader classes of soft-matter models and systems. [ABSTRACT FROM AUTHOR]

How to fabricate perpendicularly oriented domains (PODs) of lamellar and cylinder phases in block copolymer thin films remains a major challenge. In this work, via a coarse-grained molecular dynamics simulation study, we report a solvent evaporation strategy starting from a mixed solution of A-b-B-type diblock copolymers (DBCs) and single-chain nanoparticles (SCNPs) with the same composition, which is capable of spontaneously generating PODs in drying DBC films induced by the interface segregation of SCNPs. The latter occurs at both the free surface and substrate and, consequently, neutralizes the interface selectivity of distinct blocks in DBCs, leading to spontaneous formation of PODs at both interfaces. The interface segregation of SCNPs is related to the weak solvophilicity of the internal cross-linker units. A mean-field theory calculation demonstrates that the increase in the chemical potential of SCNPs in the bulk region drives their interface segregation along with solvent evaporation. We believe that such a strategy can be useful in regulating the PODs of DBC films in practical applications. [ABSTRACT FROM AUTHOR]

Self‐assembly behaviors of special topological polymers such as 8‐figure shaped cyclic polymer are interesting, but are rarely reported so far due to the limited availability. In this work, mikto 8‐figure shaped cyclic copolymers are synthesized with cinnamic acid dimer junctions, in which both rings possess diblock PSx‐b‐PEGy structures. Their self‐assembly in water is investigated in comparison with their corresponding linear precursors. According to scanning electron microscopic (SEM) and transmission electron microscopic (TEM) observation, both of the mikto 8‐figure shaped cyclic polymers and their corresponding linear precursors can form vesicles. But those formed from the former have very smooth surfaces, while those from the linear precursors have rugous surfaces. TEM observation shows that the linear precursors form loose vesicles. The size of micelles formed from 8‐shaped cyclic copolymers is much smaller than that formed from the linear precursors. The topological structure exerts a significant influence on the solution aggregation behavior and provides broad ideas for the construction of precision solution aggregates. [ABSTRACT FROM AUTHOR]

Diblock copolymers consisting of higher hydrophobic styrene and hydrophilic N-hydroxyethylacrylamide (HEAAm) segments were successfully synthesized via direct two-step atom transfer radical polymerization. Polystyrene (PS) homopolymers were synthesized using methyl 4-(bromo-methyl) benzoate initiator in N,N′- dimethylformamide (DMF) in the presence of Cu(I)Br/pentamethyldiethylene tetramine (PMDETA) catalyst system at 90 and 110 °C in nitrogen atmosphere. PS was used as macro-initiator for the synthesis of PS-b-PHEAAm polymer. Block copolymerizations were carried out in pure DMF in the presence of the same catalyst system at 110 °C while argon was used for deoxygenation and inert environment. Block copolymer was purified through dialysis into deionized water using a dialysis tubing (MWCO 3500, cellulose membrane). The number average molecular weight of PS polymers (Mn = 2240, 3250 and 10,800 Da) was determined by size exclusion chromatography using tetrahydrofuran (THF) as eluent. The chemical structures, functional groups and actual compositions of copolymer were determined using instrumental data, c.f. elemental analysis, attenuated total reflectance infra-red and proton—nuclear magnetic resonance (1H-NMR) spectroscopy analysis. Thermo-gravimetric analysis confirms that diblock copolymer has higher thermal stability than PS homopolymer. Co-solvent effect on particle formation was investigated by regulating dielectric constant. It is revealed that THF/DMF (9:1) provides susceptible environment for the formation of smallest size (13 ± 4 nm) particle. This synthetic route would establish a direct synthesis of diblock copolymer with antagonistic segments for advanced technological applications. [ABSTRACT FROM AUTHOR]

The polyethylene oxide‐polypropylene oxide (PEO‐PPO) based triblock copolymers are notable amphiphilic copolymers with a diverse range of applications. The presence of homo‐, and/or diblock impurities in copolymers with PEO‐PPO‐PEO triblock has been demonstrated. This finding suggests that the samples are blends rather than pure triblock copolymers. Furthermore, copolymers with triblock copolymer content of 0 or less than 20% by molar percentage have been identified. The hydrophilic‐lipophilic balance (HLB) is also calculated based on the exact composition of the blends. The effect of HLB values and compositional data on the initial foam height (in casein solution), the surface tension, and the contact angle are investigated. The correlation coefficients for the PPO‐PEO‐PPO copolymers versus HLB values are found to be high, while those obtained for the PEO‐PPO‐PEO copolymers versus values of HLB are significantly lower. The lower correlation coefficients for the PEO‐PPO‐PEO samples can be attributed to the presence of homo‐ and diblock (co)polymer contaminants. In addition, a linear regression model has been constructed to find a mathematical relationship between the percentage of ethylene oxide, the average number of propylene oxide units, and the properties of the copolymer. [ABSTRACT FROM AUTHOR]

Efficient occlusion of particulate additives into a single crystal has garnered an ever‐increasing attention in materials science because it offers a counter‐intuitive yet powerful platform to make crystalline nanocomposite materials with emerging properties. However, precisely controlling the spatial distribution of the guest additives within a host crystal remains highly challenging. We herein demonstrate a unique, straightforward method to engineer the spatial distribution of copolymer nanoparticles within calcite (CaCO3) single crystals by judiciously adjusting initial [Ca2+] concentration used for the calcite precipitation. More specifically, polymerization‐induced self‐assembly is employed to synthesize well‐defined and highly anionic poly(3‐sulfopropyl methacrylate potassium)41‐block‐poly(benzyl methacrylate)500 [PSPMA41‐PBzMA500] diblock copolymer nanoparticles, which are subsequently used as model additives during the growth of calcite crystals. Impressively, such guest nanoparticles are preferentially occluded into specific regions of calcite depending on the initial [Ca2+] concentration. These unprecedented phenomena are most probably caused by dynamic change in electrostatic interaction between Ca2+ ions and PSPMA41 chains based on systematic investigations. This study not only showcases a significant advancement in controlling the spatial distribution of guest nanoparticles within host crystals, enabling the internal structure of composite crystals to be rationally tailored via a spatioselective occlusion strategy, but also provides new insights into biomineralization. [ABSTRACT FROM AUTHOR]

The urgent need to mitigate climate change has spurred research into innovative carbon dioxide (CO2) capture materials. In this study, the design and synthesis of CO2‐responsive diblock copolymers, poly (N‐[3‐(dimethylamino)propyl]‐acrylamide)‐b‐poly(methyl methacrylate) (PDMAPAm‐b‐PMMA) are focused on via a two‐step reversible addition−fragmentation chain‐transfer (RAFT) polymerization as well as the application of the synthesized diblock copolymer as a membrane for CO2 capture. The resulting diblock copolymer possesses distinct blocks with varying properties. The poly (N‐[3‐(dimethylamino)propyl]‐acrylamide) (PDMAPAm) block provides CO2‐responsive behavior, while the poly(methyl methacrylate) (PMMA) block contributes to mechanical stability. The gas transport properties of the fabricated thin‐film composite membrane made of PDMAPAm‐b‐PMMA are measured. It is determined that the copolymer exhibits dual responsiveness towards CO2 and can be tailored for use in fabrication of membranes for direct air capture (DAC). [ABSTRACT FROM AUTHOR]

The microphase-separated structures of block copolymers are inherently highly ordered local structures, commonly characterized by differences in domain width and curvature. By focusing on diblock copolymers, we propose local order parameters (LOPs) that accurately distinguish between adjacent microphase-separated structures on the phase diagram. We used the Molecular Assembly structure Learning package for Identifying Order parameters (MALIO) to evaluate the structure classification performance of 186 candidate LOPs. MALIO calculates the numerical values of all candidate LOPs for the input microphase-separated structures to create a dataset, and then performs supervised machine learning to select the best LOPs quickly and systematically. We evaluated the robustness of the selected LOPs in terms of classification accuracy against variations in miscibility and fraction of block. The minimum local area size required for LOPs to achieve their classification performances is closely related to the characteristic sizes of the microphase-separated structures. The proposed LOPs are potentially applicable over a large area on the phase diagram. [ABSTRACT FROM AUTHOR]

Diblock copolymers of phenyl methacrylate (PMA) and butyl methacrylate (BMA) were synthesized using dual-wavelength photopolymerization with a bifunctional photoinitiator 2-(4-(2-hydroxy-2-methylpropanoyl)phenoxy)ethyl(E)-3-(1-methyl-1H-pyrrol-2-yl)acrylate (PAA-2959). [ABSTRACT FROM AUTHOR]

In this study, we aim to synthesize self-assembled amphiphilic diblock poly(PEGA-b-HEA-PCL) copolymers through RAFT living polymerization, targeting the delivery of hydrophobic anticancer drugs. The synthesized self-assembled diblock copolymers polymeric micelles (PMs) comprising poly(ethylene glycol) methyl ether acrylate (PEGA), as a hydrophilic segment and 2-hydroxyethyl acrylate-polyhexanoate monomer (HEA-PCL) with different block lengths, as a hydrophobic segment. The chemical structures, compositions, and self-assembled behavior were identified through 1H NMR spectroscopy. The thermal stability was assessed through TGA and DSC. Furthermore, DOX was encapsulated into all PMs. The drug-loaded PMs exhibited enhanced drug release profiles in acidic medium. Particle diameter was measured through DLS and TEM techniques. The cell viability of diblock polymers and selected DOX-loaded PMs were evaluated against non-cancerous (L929) and cancerous cells (SK-N-AS), respectively, through well-known MTT assay. Micellar aggregates with mean diameters of approximately 127.2–145.3 nm formed in aqueous solution. The diameters of PMs increased to 141.5–173.1 nm upon the incorporation of DOX. The drug loading content and encapsulation efficiency of PMs were approximately 8.09–18.84% and 30.43–54.07%, respectively. The MTT assay results indicated that all synthesized materials had minimal effects on the viability of L929 cells, while DOX-loaded materials inhibited the viability of neuroblastoma cells by 68.7%. The highest drug release was 89.20% at pH 7.4, while 83.45% at pH 5.0 for 40 h. These findings suggest that the synthesized amphiphilic PMs are promising candidates for drug delivery systems. [ABSTRACT FROM AUTHOR]

Self-consistent field (SCF) analysis is an indispensable tool for predicting the microphase separation structures of polymer alloys. However, the computation of the phase-separated structures in the equilibrium state is computationally intensive, leading to high costs. To address this challenge, we propose a novel deep learning approach that leverages a generative adversarial network (GAN), a powerful deep generative model, to accelerate SCF analysis. Specifically, we trained the GAN using comprehensive data obtained from SCF analysis, enabling us to generate various images of feasible structures that are similar to the SCF analysis results. Our results demonstrate that the latent variables in the GAN are linked to the physical parameters and features of the phase-separation structures. [ABSTRACT FROM AUTHOR]

The self‐assembly and dynamics of amphiphilic diblock copolymers composed of densely grafted poly(oligo ethylene glycol methacrylate) (POEGMA) and poly(lauryl methacrylate) (PLMA) by means of calorimetry, small‐angle X‐ray scattering (SAXS), and dielectric spectroscopy are investigated. It is reported that the inherent immiscibility between the parent homopolymers, combined with the increased molar mass, results in strong segregation, maintained up to elevated temperatures (i.e., T = 423 K). SAXS reveals that well‐separated POEGMA and PLMA domains self‐assemble into spheres with bicontinuous cubic packing and in lamellar nanostructure in copolymers with respective compositions of 16 and 52 wt.% PLMA. This strong segregation enables the weak crystallization/melting of the short ethylene glycol chains. Additionally, molecular dynamics are investigated through isothermal dielectric and calorimetry measurements. The segmental dynamics (i.e., Tg‐related) of POEGMA and PLMA closely resemble that found in respective homopolymers, implying heterogeneous dynamics. In the glassy state, the local motions of the POEGMA side chains predominantly govern the observed secondary processes in the copolymers. The results on the heterogeneous dynamics in the current amphiphilic diblock copolymers with the densely grafted architecture are compared and contrasted with copolymers having a bottle–brush architecture lacking the amphiphilic nature. [ABSTRACT FROM AUTHOR]

Hypothesis : Amphiphilic diblock copolymers are known to increase the surfactant's efficiency to stabilize microemulsion, leading to higher structural order and monolayer rigidity. We thus seek to evaluate whether the addition of such polymers alters the shear behavior of bicontinuous microemulsions, in particular, their shear transformation towards lamellar structures. Experiments : We examine the initial structure and shear response of bicontinuous ▪/ n -octane/▪/PEP 5 - b -PEO 5 microemulsions by coupling microfluidics with small-angle neutron scattering (SANS), attaining wall shear rates in excess of ▪. The azimuthal analysis of the obtained 2D scattering patterns allows us to follow their structural transformation by means of the degree of anisotropy. Findings : The amphiphilic diblock copolymer promotes the shear-induced transformation of bicontinuous microemulsions, resulting in up to ∼▪ higher degrees of anisotropy than for corresponding polymer-free microemulsions. The increased shear response observed with increasing polymer content is rationalized by combining the influence of domain size and viscosity with the stability limits of the bicontinuous microemulsion in the isothermal phase diagram. As a result, a consistent description of the degree of anisotropy is obtained, enabling the prediction of the shear-induced bicontinuous-to-lamellar transformation. [ABSTRACT FROM AUTHOR]

The development of controlled chain‐growth click polymerization is desirable yet challenging in polymer chemistry. Here, we reported an efficient controlled chain‐growth thiol‐Michael polymerization using the thiol as an initiator. This polymerization could proceed efficiently without any catalysts under mild conditions, yielding sulfur‐containing polymers with controlled molecular weights. The synthetic utility of this polymerization was further demonstrated by incorporating various functional groups into the polymer backbone and synthesizing diblock copolymers and star polymers. This work represents a new type of controlled chain‐growth click polymerization and will open up new opportunities for polymer synthesis. [ABSTRACT FROM AUTHOR]

Sulfur dots (S‐dots) eliminate the need of expensive and toxic conventional photocatalysts or transition metal in photoinduced reversible deactivation radical polymerization (photoRDRP). Herein, non‐metallic S‐dots mediated photoRDRP of N,N‐dimethyl acrylamide (DMA) are developed for the first time. This technique allows for the precise synthesis of narrow‐dispersed poly(N,N‐dimethyl acrylamide) (PDMA) and double hydrophilic poly(N, N‐dimethyl acrylamide)‐block‐poly(2‐hydroxyethyl acrylamide) (PDMA‐b‐PHEAA) diblock copolymer suitable for contaminant removal from water. Also, its subsequent modification into a poly(N,N‐dimethyl acrylamide)‐block‐poly(N‐(2‐((4‐vinylbenzyl)oxy)ethyl)acrylamide) (PDMA‐b‐PVBEAA) diblock copolymer gives ultra‐fast gelation and production of writable ink‐gel, which is exceptionally well‐suited for 3D printing applications, enabling the creation of precise and defined shapes. This innovative material serves as an intriguing scaffold for tissue engineering and other biomaterial applications, especially in areas that demand rapid and customizable manufacturing solutions. [ABSTRACT FROM AUTHOR]

Lamellae forming polystyrene‐b‐poly‐2‐vinylpyridine diblock copolymer melts are investigated with linear shear rheology and Fourier transformation rheology (FT rheology) to quantify their nonlinear behavior under oscillatory shear via mechanical higher harmonic contributions such as I3/1(ω1, γ0). The determination of the zero‐shear nonlinearity (3Q0(ω)≡limγ0→0I3/1/γ02$^3Q_0(\omega)\equiv \lim _{\gamma _0 \rightarrow 0}I_{3/1}/\gamma _0^2$) by a variation of γ0 is hindered by the increasing domain alignment at increasing γ0. Thus, an approach for determining 3Q0(T) by a variation of the temperature is developed and used. This approach allows obtaining insights on the nonlinear behavior directly at temperature‐dependent phase transitions, such as at the order‐disorder transition temperature TODT of block copolymers. The maximum of 3Q0 is found to be close to TODT. The nonlinearity originating from the connection of the unequal polymer blocks is shown to dominate the overall nonlinearity, and the maximum of 3Q0(T) correlates to domain alignment for T < TODT. [ABSTRACT FROM AUTHOR]

We investigate the solution self-assembly of a mixture of positively charged homopolymers and AB diblock copolymers, in which the A blocks are negatively charged, and the B blocks are neutral. The electrostatic complexation between oppositely charged polymers drives the formation of many ordered phases. The microstructures and phase diagrams are calculated using self-consistent field theory (SCFT) based on an ion-pair model with an equilibrium constant K to characterize the strength of binding between positively and negatively charged monomers. The effects of the charge ratio, representing the ratio of charges from the homopolymer over all charges from polymers in the system, on the ordered structure are systematically studied, both for hydrophobic and hydrophilic A blocks. The charge ratio plays an important role in determining the phase boundaries in the phase diagram of salt concentration versus polymer concentration. We also provide information about the varying tendency of the domain spacing and core size of the spherical phase when the charge ratio is changed, and the results are in good agreement with experiments. These studies provide a deep understanding of the self-assembled microstructures of oppositely charged diblock copolymer-homopolymer systems. [ABSTRACT FROM AUTHOR]

Salt-doped block copolymers have widespread applications in batteries, fuel cells, semiconductors, and various industries, where their properties crucially depend on phase separation behavior. Traditionally, investigations into salt-doped diblock copolymers have predominantly focused on microphase separation, overlooking the segregation between ionic and polymeric species. This study employs weak segregation theory to explore the interplay between phase separation dominated by the polymer-modulated mode and the salt-out-modulated mode, corresponding to microscopic and macroscopic phase separations, respectively. By comparing diblock copolymers doped with salts to those doped with neutral solvents, we elucidate the significant role of charged species in modulating phase behavior. The phase separation mode exhibits a transition between the polymer-modulated and salt-out-modulated modes at different wavenumbers. In systems doped with neutral solvents, this transition is stepwise, while in salt-ion-doped systems, it is continuous. With a sufficiently large Flory-Huggins parameter between ions and polymers, the salt-out-modulated mode becomes dominant, promoting macrophase separation. Due to the solvation effect of salt ions, salt-doped systems are more inclined to undergo microphase separation. Furthermore, we explore factors influencing the critical wavenumber of phase separation, including doping level and the Flory-Huggins parameters between two blocks and between ions and polymeric species. Our findings reveal that in a neutral solvent environment, these factors alter only the boundary between micro- and macro-phase separations, leaving the critical wavenumber unchanged in microphase separation cases. However, in a salt-doped environment, the critical wavenumber of microphase separation varies with these parameters. This provides valuable insights into the pivotal role of electrostatics in the phase separation of salt-doped block copolymers. [ABSTRACT FROM AUTHOR]

The aim of this work was to the obtaining novel mixed-mode stationary phases with increased hydrophilicity and applying them in ion and hydrophilic interaction liquid chromatography. The resins were obtained by the sequential covalent attachment of branched polyethylenimine and polyelectrolytes synthesized from diepoxide and a secondary amine on the surface of epoxidized polystyrene–divinylbenzene. To increase the shielding degree of the polymer substrate, an additional polymerization of glycidol was carried out in the functional layer of the sorbent at an increased pH of the reaction medium. The synthesized phases possessed increased hydrophilicity compared to most resins based on a styrene–divinylbenzene copolymer with covalently attached layers. This was evidenced in the ion chromatography mode by a decrease in the relative retention of polarizable anions, weakly hydrated oxyhalides (up to a change in the elution order of the bromate), and haloacetic acids. In the hydrophilic interaction liquid chromatography mode, an increased hydrophilicity of the phases was confirmed by an increase in the retention factors of polar analytes, as well as by the reversal of the elution order of ascorbic and nicotinic acids as compared to the phases based on polystyrene–divinylbenzene presented in the literature. The low efficiency of the obtained stationary phases in the ion chromatography mode was noted, which is associated with slow mass transfer in the bulk polymer functional layer. The negative impact of the polymer layer on efficiency in hydrophilic interaction liquid chromatography is less pronounced due to the presumably smaller thickness of the part of the functional layer involved in this mode. The proposed method for the synthesis of resins ensures an increase in the efficiency, selectivity, and separation ability of sorbents in the hydrophilic interaction liquid chromatography mode as compared to phases based on a styrene–divinylbenzene copolymer described previously in the literature. The resulting highly hydrophilic resins makes it possible to separate a mixture of 9 nitrogenous bases and nucleosides in 18 min, 6 vitamins in 24 min, and 8 sugars in 11 min. Thus, the method of substrate hydrophilization proposed in this work is promising for improving the chromatographic characteristics of phases in the hydrophilic interaction liquid chromatography mode and can be used to create sorbents with increased selectivity and efficiency. [ABSTRACT FROM AUTHOR]

Purpose: To save the economic cost and improve the performance of enterprises, this study aims to synthesize high performance immobilized penicillin G acylase (PGA) carriers with fast reaction speed, high recovery rate of enzyme activity and good reusability through corresponding theoretical guidance and experimental exploration. Design methodology approach: A diblock resin was synthesized by reversible addition-fragmentation chain transfer polymerization method using N, N-diethylacrylamide (DEA) and β-hydroxyethyl methacrylate (HEMA) as functional monomers poly(N, N-diethylacrylamide)-b-poly(β-hydroxyethyl methacrylate) (PDEA-b-PHEMA) was obtained, and the effect of the ratio of DEA and HEMA on the activity of PGA was investigated, and the appropriate block ratio of DEA and HEMA was obtained. After that, the competitive rate of HEMA and glycidyl methacrylate (GMA) under the carrier preparation conditions was investigated. Based on the above work, a thermosensitive resin carrier PDEA-b-PHEMA-b-P(HEMA-co-GMA) with different target distances was synthesized, and the chemical structures and molecular weight of copolymers were investigated by hydrogen NMR (1H NMR). Findings: The lower critical solution temperature of the resin support decreases with the increase of the monomer HEMA in the random copolymerization; the catalytic performance study indicated that the response rate of the immobilized PGA is fast, and the recovery rate of the enzyme activity of the immobilized PGA varies with the distance between the targets. When the molar ratio of HEMA to GMA in the resin block is 8.15:1 [i.e. resin PDEA100-b-PHEMA10-b-P(HEMA65-co-GMA8)], the activity recovery rate of immobilized PGA can reach 50.51%, which was 15.49% higher than that of pure GMA immobilized PGA. Originality value: This contribution provides a novel carrier for immobilizing PGA. Under the optimal molar ratio, the enzyme activity recovery could be up to 50.51%, which was 15.49% higher than that of PGA immobilized on the carrier with nonregulated distance between two immobilization sites. [ABSTRACT FROM AUTHOR]

Particle-based and field-theoretic simulations are both widely used methods to predict the properties of polymeric materials. In general, the advantages of each method are complementary. Field-theoretic simulations are preferred for polymers with high molecular weights and can provide direct access to chemical potentials and free energies, which makes them the method-of-choice for calculating phase diagrams. The trade-off is that field-theoretic simulations sacrifice the molecular details present in particle-based simulations, such as the configurations of individual molecules and their dynamics. In this work, we describe a new approach to conduct "multi-representation" simulations that efficiently map between particle-based and field-theoretic simulations. Our approach involves the construction of formally equivalent particle-based and field-based models, which are then simulated subject to the constraint that their spatial density profiles are equal. This constraint provides the ability to directly link particle-based and field-based simulations and enables calculations that can switch between one representation to the other. By switching between particle/field representations during a simulation, we demonstrate that our approach can leverage many of the advantages of each representation while avoiding their respective limitations. Although our method is illustrated in the context of complex sphere phases in linear diblock copolymers, we anticipate that it will be useful whenever free energies, rapid equilibration, molecular configurations, and dynamic information are all simultaneously desired. [ABSTRACT FROM AUTHOR]

Integration of hexagonal boron nitride (h-BN) with plasmonic nanostructures that possess nanoscale field confinement will enable unusual properties; hence, the manipulation and understanding of the light interactions are highly desirable. Here, we demonstrate the surface plasmonic coupling of Au nanoparticles (ANPs) with ultrathin h-BN nanosheets (BNNS) in nonspecific nanocomposites leading to a great enhancement of the Raman signal of E2g in both experimental and theoretical manner. The nanocomposites were fabricated from liquid-exfoliated atomically thin BNNS and diblock copolymer-based ANPs with excellent dispersion through a self-assembly approach. By precisely varying the size of ANPs from 3 to 9 nm, the Raman signal of BNNS was improved from 1.7 to 71. In addition, the underlying mechanism has been explored from the aspects of electromagnetic field coupling strength between the localized surface plasmons excited from ANPs and the surrounding dielectric h-BN layers, as well as the charge transfer at the BNNS/ANPs interfaces. Moreover, we also demonstrate its capability to detect dye molecules as a surface enhanced Raman scattering (SERS) substrate. This work provides a basis for the self-assembly of BNNS hierarchical nanocomposites allowing for plasmon-mediated modulation of their optoelectronic properties, thereby showing the great potential not only in the field of SERS but also in large-scale h-BN-based plasmonic devices. [ABSTRACT FROM AUTHOR]

The increasing water pollution problem poses a demand for oil–water separation materials, but preparing separation materials with high efficiency and excellent durability remains a great challenge. In this work, we use a diblock polymer brush of polydimethylsiloxane (PDMS) and poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) based on cotton fabric to prepare oil–water separation membranes with high efficiency, good durability, and intelligent self‐repairing properties. Lubricating PDMS brushes reduces the fouling adhesion due to its low surface energy and high flexibility. pH‐responsive PDMAEMA brushes provide good hydrophobicity and an intelligent self‐repairing effect. The prepared Co‐PDMS‐PDMAEMA has high oil flux (>30,000 L m−2 h−1) and high separation efficiency (>99%) even after 10 cycles and its surface character can be recovered under acidic conditions. Overall, the modified cotton fabric made by such a versatile technique is promising in oil–water separation. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Nitrogen‐containing polymers have found a wide myriad of applications in materials science and other different areas, and have attracted much attention towards the development of new synthetic methods. Ring‐opening metathesis polymerization represents an area of great versatility and potential for the synthesis of highly functionalized polymers with low dispersity and control over molecular weight and architecture complexity. Expanding the scope of monomers through the incorporation of nitrogen atoms would further expand their utilities. In this work, a controlled synthesis of polymers with in‐chain enamide moiety through ring‐opening metathesis polymerization was developed by utilizing azetine derivatives as the monomers. Relatively short synthetic routes were designed and generated a panel of five monomers. The polymerization exhibited living characteristics, as linear relationship between molecular weights and degrees of polymerization and relatively narrow molar mass distributions were observed, which was further confirmed by successful diblock copolymers formation through sequential addition of two monomers. The resulting polymers that contain the enamide moiety within the backbone exhibited good stability and underwent facile degradation under acidic conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] Pickering emulsions stabilized using epoxy-functional block copolymer nanoparticles should enable the formation of sub-micron colloidosomes that are stable with respect to Ostwald ripening and allow tuneable small-molecule cargo release. Epoxy-functional diblock copolymer nanoparticles of 24 ± 4 nm were prepared via reversible addition-fragmentation chain transfer (RAFT)-mediated dispersion polymerization of methyl methacrylate (MMA) in n -dodecane. Sub-micron water-in- n -dodecane Pickering emulsions were prepared by high-pressure microfluidization. The epoxy groups were then ring-opened using 3-aminopropyltriethoxysilane (APTES) to prepare cross-linked colloidosomes. The colloidosomes survived removal of the aqueous phase using excess solvent. The silica shell thickness could be adjusted from 11 to 23 nm by varying the APTES/GlyMA molar ratio. The long-term stability of the colloidosomes was compared to precursor Pickering emulsions. Finally, the permeability of the colloidosomes was examined by encapsulation and release of a small molecule. The Pickering emulsion droplet diameter was reduced from 700 to 200 nm by increasing the salt concentration within the aqueous phase. In the absence of salt, emulsion droplets were unstable due to Ostwald ripening. However, emulsions prepared with 0.5 M NaCl are stable for at least one month. The cross-linked colloidosomes demonstrated much more stable than the precursor sub-micron emulsions prepared without salt. The precursor nanoemulsions exhibited complete release (>99 %) of an encapsulated dye, while higher APTES/GlyMA ratios resulted in much lower dye release, yielding nearly impermeable silica capsules that retained around 95 % of the dye. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Nitrogen‐containing polymers have found a wide myriad of applications in materials science and other different areas, and have attracted much attention towards the development of new synthetic methods. Ring‐opening metathesis polymerization represents an area of great versatility and potential for the synthesis of highly functionalized polymers with low dispersity and control over molecular weight and architecture complexity. Expanding the scope of monomers through the incorporation of nitrogen atoms would further expand their utilities. In this work, a controlled synthesis of polymers with in‐chain enamide moiety through ring‐opening metathesis polymerization was developed by utilizing azetine derivatives as the monomers. Relatively short synthetic routes were designed and generated a panel of five monomers. The polymerization exhibited living characteristics, as linear relationship between molecular weights and degrees of polymerization and relatively narrow molar mass distributions were observed, which was further confirmed by successful diblock copolymers formation through sequential addition of two monomers. The resulting polymers that contain the enamide moiety within the backbone exhibited good stability and underwent facile degradation under acidic conditions. [ABSTRACT FROM AUTHOR]

A general theory has been developed for a polydisperse semi-flexible multi-block copolymer melt. Using the Bawendi–Freed approach to model semi-flexible chains, an expression for the Landau free energy is derived in the weak segregation regime, which includes density and orientation order-parameters. The orientation order-parameter is described in the smectic phase and in more complicated structures, such as the hexagonal phase. The Landau free energy contains contributions of two kinds of interactions. The first kind is the Flory–Huggins interaction, which describes the incompatibility of chemically different blocks and may induce microphase separation. The second kind is the Maier–Saupe interaction, which may induce nematic ordering. In the framework of the weak segregation limit, the Landau theory allows us to predict phase structures in the melt as a function of the composition, persistence length, and the strength of the Flory–Huggins and Maier–Saupe interaction. The general theory is applied to a simple system of monodisperse semi-flexible diblock copolymers. In several phase diagrams, a number of possible phase structures are predicted, such as the bcc, hexagonal, smectic-A, smectic-C, and nematic phase. The influence of the Maier–Saupe interaction on the microphase structure is thoroughly discussed. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Chemical Communications" published in 2024. It includes various articles on topics such as latent fingerprint detection, MXene materials in electrochemical energy storage systems, sustainable production of metal-organic frameworks, and more. The journal is published by The Royal Society of Chemistry, a leading chemistry community. The document provides a brief overview of the articles included in the journal issue, allowing library patrons to quickly identify relevant research topics. [Extracted from the article]

Reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization of methyl methacrylate (MMA) is successfully performed in water in the presence of a poly(methacrylic acid) (PMAA) macromolecular chain transfer agent (macroCTA) leading to the formation of self‐stabilized PMAA‐b‐PMMA amphiphilic block copolymer particles. At pH 3.7, the reactions are well‐controlled with narrow molar mass distributions. Increasing the initial pH, particularly above 5.6, results in a partial loss of reactivity of the PMAA macroCTA. The effect of the degree of polymerization (DPn) of the PMMA block, the solids content, the nature of the hydrophobic segment, and the pH on the morphology of the obtained diblock copolymer particles is then investigated. Worm‐like micelles are formed for a DPn of PMMA of 20 (PMMA20), while "onion‐like" particles and spherical vesicles are obtained for PMMA30 and PMMA50, respectively. In contrast, spherical particles are obtained for the DPns higher than 150. This unusual evolution of particle morphologies upon increasing the DPn of the PMMA block seems to be related to hydrogen bonds between hydrophilic MAA and hydrophobic MMA units. [ABSTRACT FROM AUTHOR]

A dual zwitterionic diblock copolymer (M100C100) consisting of poly(2‐(methacryloyloxy)ethyl phosphorylcholine) (PMPC, M) and poly(3‐((2‐(methacryloyloxy)ethyl) dimethylammonio) propionate) (PCBMA, C) is synthesized via reversible addition‐fragmentation chain transfer (RAFT) polymerization. A double hydrophilic diblock copolymer (M100S100) consist of PMPC and anionic poly(3‐sulfopropyl methacrylate potassium salt) (PMPS, S) is synthesized via RAFT. The degrees of polymerization of each block are 100. The charges of PMPC are neutralized intramolecularly. At neutral pH, the charges in PCBMA are also neutralized intramolecularly due to its carboxybetaine structure. Under acidic conditions, PCBMA exhibits polycation behavior as the pendant carboxy groups become protonated, forming cationic tertiary amine groups. PMPS shows permanent anionic nature independent of pH. Charge neutralized mixture of cationic M100C100 and anionic M100S100 in acidic aqueous solution forms water‐soluble polyion complex (PIC) micelle owing to electrostatic attractive interactions. The core is composed of the cationic PCBMA and anionic PMPS blocks, with the PMPC blocks serving as shells that covered the core surface, forming spherical core–shell PIC micelles. Above pH 4 the pendant carboxy groups in PCBMA undergo deprotonation, transitioning to a zwitterionic state, thereby eliminating the cationic charge in PCBMA. Therefore, above pH 4 the PIC micelles are dissociated due to the disappearance of the charge interactions. [ABSTRACT FROM AUTHOR]

Aqueous solutions of a thermoresponsive diblock copolymer poly(di-[ethylene glycol] methyl ether methacrylate)-b-poly(2-[diisopropylamino] ethyl methacrylate) (PDEGMA-b-PDIPAEMA) were studied by static, dynamic and electrophoretic light scattering, small-angle X-ray scattering and differential scanning calorimetry. Thermoresponsive behavior of PDEGMA-b-PDIPAEMA was investigated at two pH values, pH = 2, at which the terminal carboxylic group of the PDEGMA chain and the PDIPAEMA block are protonated, and pH = 7, where the carboxyl terminal group is ionized while the PDIPAEMA block is partially deprotonated and more hydrophobic. Both at pH = 2 and 7, PDEGMA-b-PDIPAEMA copolymer underwent extensive association (the size of the aggregates was between 100 and 300 nm), indicating strong interchain interactions. While the measurements confirmed thermoresponsive behavior of PDEGMA-b-PDIPAEMA at pH = 7, no changes in the association with temperature were observed at pH 2 as the thermoresponsivity of PDEGMA was suppressed by hydrogen bonding between carboxylic groups and PDEGMA segments, as well as due to the increased hydrophilicity of the PDIPAEMA block. Fluorescence measurements with pyrene as a fluorescent probe showed that both at pH = 2 and pH = 7 the associates were able to solubilize hydrophobic substances. [ABSTRACT FROM AUTHOR]

The design of block‐copolymer‐based functional materials, including mesoporous membranes and nanoparticles, requires a comprehensive understanding of the hierarchical assembly of block copolymers in selective solvents into micelles and subsequent ordered phases. It is hypothesized that micellar ordering and characteristic assembly can be described using a set of phase parameters that account for entropic and enthalpic interactions. Dissipative particle dynamics (DPD) simulations are used to systematically investigate the self‐assembly of semidiluted block copolymers, resembling isoporous membrane preparation conditions. The effect of Flory–Huggins interaction parameters, block lengths, and concentration on the morphology and polydispersity of the micelles is evaluated. The interaction parameters are mapped into Flory–Huggins theory by considering the block's conformation. These results reveal the effect of polymer concentration and solvent affinity on the morphological transition of the aggregates, in agreement with existing experimental evidence. It is identified that monodisperse‐spherical micelles in solution are fundamental to stabilize ordered states. Weak solvent segregation of the largest block, curvature of the core‐corona interface, and stretching of the corona‐forming one are found to be key to stabilize monodisperse assemblies. These conditions can be predicted using spherical‐micelles packing considerations and a global phase parameter from the Flory–Huggins theory. This study provides valuable insights into the self‐assembly of diblock copolymers and offers a potential way to optimize the preparation of mesoporous ordered structures and micelle ordering in semidiluted systems. [ABSTRACT FROM AUTHOR]

Bio‐based, fully degradable aliphatic‐aromatic block copolymers are synthesized from ω‐pentadecalatone and cyclic oligo(3,4‐ethylene furanoate). In the first approach, the ring‐opening polymerization of the cyclic oligo(3,4‐ethylene furanoate) is initiated by a poly(pentadecalactone) macroinitiator with a terminal hydroxy group. The reaction temperatures of the melt polymerization are 210–230 °C due to the high melting points of the oligo(3,4‐ethylene furanoate). Under these conditions, transesterification is observed. The blockiness of the reaction products depends on the reaction temperature and on the ratio of pentadecalactone to 3,4‐ethylene furanoate repeat units, which is 50:50, 80:20, and 90:10. At lower temperatures and more pentadecalactone content, the blockiness is larger. The number average molar mass of the block copolymers remains smaller than 20 000 g mol−1. In the second approach, poly(pentadecalactone) is functionalized with an alkyne group, and the OH group of the oligo(3,4‐ethylene furanoate) (molar mass 1900 g mol−1) is converted into an azide group. Connecting the two polymers in a copper‐catalyzed 1,3‐dipolar addition reaction ("click reaction") yields block copolymers with a number average molar mass of 12 400 g mol−1. The mechanical properties of the polymer films are intermediate between those of the parent homopolymers. [ABSTRACT FROM AUTHOR]

The electrostatic attraction between charges of opposite signs and the repulsion between charges of the same sign are ubiquitous and influential phenomena in recognition and self-assembly processes. However, it has been recently revealed that specific attractive forces between ions with the same sign are relatively common. These forces can be strong enough to overcome the Coulomb repulsion between ions with the same sign, leading to the formation of stable anion⋯anion and cation⋯cation adducts. Hydroden bonds (HBs) are probably the best-known interaction that can effectively direct these counterintuitive assembly processes. In this review we discuss how σ-hole and π-hole bonds can break the paradigm of electrostatic repulsion between like-charges and effectively drive the self-assembly of anions into discrete as well as one-, two-, or three-dimensional adducts. σ-Hole and π-hole bonds are the attractive forces between regions of excess electron density in molecular entities (e.g., lone pairs or π bond orbitals) and regions of depleted electron density that are localized at the outer surface of bonded atoms opposite to the σ covalent bonds formed by atoms (σ-holes) and above and below the planar portions of molecular entities (π-holes). σ- and π-holes can be present on many different elements of the p and d block of the periodic table and the self-assembly processes driven by their presence can thus involve a wide diversity of mono- and di-anions. The formed homomeric and heteromeric adducts are typically stable in the solid phase and in polar solvents but metastable or unstable in the gas phase. The pivotal role of σ- and π-hole bonds in controlling anion⋯anion self-assembly is described in key biopharmacological systems and in molecular materials endowed with useful functional properties. [ABSTRACT FROM AUTHOR]

The microphase separation of high-molecular-weight block copolymers into nanostructured films is strongly dependent on the surface fields. Both, the chain mobility and the effective interaction parameters can lead to deviations from the bulk morphologies in the structures adjacent to the substrate. Resolving frustrated morphologies with domain period L0 above 100 nm is an experimental challenge. Here, solvothermal annealing was used to assess the contribution of elevated temperatures of the vapor Tv and of the substrate Ts on the evolution of the microphase-separated structures in thin films symmetric of polystyrene-b-poly(2vinylpyridine) block copolymer (PS-PVP) with L0 about 120 nm. Pronounced topographic mesh-like and stripe patterns develop on a time scale of min and are attributed to the perforated lamella (PL) and up-standing lamella phases. By setting Tv/Ts combinations it is possible to tune the sizes of the resulting PL patterns by almost 10%. Resolving chemical periodicity using selective metallization of the structures revealed multiplication of the topographic stripes, i.e., complex segregation of the component within the topographic pattern, presumably as a result of morphological phase transition from initial non-equilibrium spherical morphology. Reported results reveal approaches to tune the topographical and chemical periodicity of microphase separation of high-molecular-weight block copolymers under strong confinement, which is essential for exploiting these structures as functional templates. [ABSTRACT FROM AUTHOR]

[Display omitted] The co-assembly of polyelectrolytes (PE) with proteins offers a promising approach for designing complex structures with customizable morphologies, charge distribution, and stability for targeted cargo delivery. However, the complexity of protein structure limits our ability to predict the properties of the formed nanoparticles, and our goal is to identify the key triggers of the morphological transition in protein/PE complexes and evaluate their ability to encapsulate multivalent ionic drugs. A positively charged PE can assemble with a protein at pH above isoelectric point due to the electrostatic attraction and disassemble at pH below isoelectric point due to the repulsion. The additional hydrophilic block of the polymer should stabilize the particles in solution and enable them to encapsulate a negatively charged drug in the presence of PE excess. We demonstrated that diblock copolymers, poly(ethylene oxide)- block -poly(N,N-dimethylaminoethyl methacrylate) and poly(ethylene oxide)- block -poly(N,N,N-trimethylammonioethyl methacrylate), consisting of a polycation block and a neutral hydrophilic block, reversibly co-assemble with insulin in pH range between 5 and 8. Using small-angle neutron and X-ray scattering (SANS, SAXS), we showed that insulin arrangement within formed particles is controlled by intermolecular electrostatic forces between protein molecules, and can be tuned by varying ionic strength. For the first time, we observed by fluorescence that formed protein/PE complexes with excess of positive charges exhibited potential for encapsulating and controlled release of negatively charged bivalent drugs, protoporphyrin-IX and zinc(II) protoporphyrin-IX, enabling the development of nanocarriers for combination therapies with adjustable charge, stability, internal structure, and size. [ABSTRACT FROM AUTHOR]

Although sulfurated polymers promise unique properties, their controlled synthesis, particularly when it comes to complex and functional architectures, remains challenging. Here, we show that the copolymerization of oxetane and phenyl isothiocyanate selectively yields polythioimidocarbonates as a new class of sulfur containing polymers, with narrow molecular weight distributions (Mn=5–80 kg/mol with Đ≤1.2; Mn,max=124 kg/mol) and high melting points of up to 181 °C. The method tolerates different substituent patterns on both the oxetane and the isothiocyanate. Self‐nucleation experiments reveal that π‐stacking of phenyl substituents, the presence of unsubstituted polymer backbones, and the kinetically controlled linkage selectivity are key factors in maximising melting points. The increased tolerance to macro‐chain transfer agents and the controlled propagation allows the synthesis of double crystalline and amphiphilic diblock copolymers, which can be assembled into micellar‐ and worm‐like structures with amorphous cores in water. In contrast, crystallization driven self‐assembly in ethanol gives cylindrical micelles or platelets. [ABSTRACT FROM AUTHOR]

A Monte Carlo study of the compatibilization of A/B polymer blends has been performed using the bond fluctuation model. The considered compatibilizers are copolymer molecules composed of A and B blocks. Different types of copolymer structures have been included, namely, linear diblock and 4-block alternating copolymers, star block copolymers, miktoarm stars, and zipper stars. Zipper stars are composed of two arms of diblock copolymers arranged in alternate order (AB and BA) from the central unit, along with two homogeneous arms of A and B units. The compatibilization performance has been characterized by analyzing the equilibration of repulsion energy, the simulated scattering intensity obtained with opposite refractive indices for A and B, the profiles along a coordinate axis, the radial distribution functions, and the compatibilizer aggregation numbers. According to the results, linear alternate block copolymers, star block copolymers, and zipper stars exhibit significantly better compatibilization, with zipper stars showing slightly but consistently better performance. [ABSTRACT FROM AUTHOR]

[Display omitted] The anticancer drug doxorubicin hydrochloride (DX) shows a high solubility in aqueous media thanks to the positive charge in the ammonium group. This feature, however, affects the drug encapsulation in the hydrophobic domains of polymeric micelles (PMs) used for the targeted delivery of the drug. At basic pH, DX deprotonates but also acquires a negative charge in the phenolic groups of the anthracycline structure. Both the efficiency and the rate of encapsulation will be increased by choosing an appropriate pH such that the drug molecule is in neutral form. An optimal pH for the encapsulation of the DX in PMs based on commercial poloxamers and on the diblock copolymer methoxy-poly(ethylene glycol) 17 - b -poly(ε-caprolactone) 9 was determined by fluorescence spectroscopy, following the time evolution of both the intensity ratio of the first and the second emission bands of DX and its fluorescence lifetime, both sensitive to the environment polarity. Intracellular delivery of PMs encapsulated drug was followed by Confocal Scanning Laser Microscopy (CSLM). Cell viability was assessed with the sulforhodamine B (SRB) assay. By adjusting pH to 8.1 a high yield of incorporation of DX in the PMs was achieved coupled to an appreciable increase (one order of magnitude) in the drug encapsulation rate. In-vitro tests in selected cancer cell lines showed the slow release of the drug and a delay in the cytotoxic response in comparison to free DX as detected by CSLM and SRB assay. The proposed methodology paves the way for a greener, faster and more efficient encapsulation of DX in PMs. [ABSTRACT FROM AUTHOR]

Poloxamers are amphiphilic block copolymers consisting of poly(ethylene glycol) (PEG) and poly(propylene glycol) segments. Their self‐assembly and interfacial properties are tied to the relative hydrophilicity and hydrophobicity of each block and can therefore be adjusted by changing block lengths. Here, a series of PEG‐polycycloether block copolymers is synthesized that have the same structure as a poloxamer, but they encompass a rigid polycyclic backbone as the hydrophobic block. A variety of polymer structures are synthesized, for example diblock or triblock architectures, with/without olefinic units, atactic or isotactic backbone, and different block lengths. Due to their amphiphilicity, self‐assembly into spherical aggregates (diameters ranging from 64 to 132 nm) at low concentrations (critical aggregation concentration as low as 0.04 mg mL−1) is observed in water. Low surface tensions (as low as 26.7 mN m−1) are observed as well as the formation of stable high internal phase emulsions (HIPEs) irrespective of the oil/water ratio. This contrasts with the properties of the commonly used poloxamers P188 or P407 and illustrates the significance of the rigid polycycloether block. These new colloidal properties offer new prospects for applications in emulsion formulations for biomedicine, cosmetics, and the food industry. [ABSTRACT FROM AUTHOR]

Poly(9,9-di-n-octylfluorene) (PFO) is a promising material for polymer light-emitting diodes (PLEDs) due to its advantageous properties. To enhance its electron transporting capabilities, diblock polymers were synthesized by attaching polystyrene (PSt) chains of varying lengths to one end of the PFO molecule. In a comparative study with PFO homopolymer, the diblock polymers maintained similar thermal properties, absorption spectra, and photoluminescent stability, while exhibiting slightly deeper lowest unoccupied molecular orbital (LUMO) levels and higher crystallinity. Notably, diblock polymers with shorter polystyrene blocks demonstrated higher electron mobility than the PFO homopolymer and diblock polymers with excessively long polystyrene blocks. These findings suggest that the optimal chain length of the polystyrene block is crucial for maximizing electron mobility, thus offering valuable insights for designing high-performance PLED materials. [ABSTRACT FROM AUTHOR]

Coarse-grained molecular dynamics simulations are employed to investigate the spatiotemporal evolution of vesicles (polymersomes) through the self-assembly of randomly distributed amphiphilic BAB triblock copolymers with hydrophilic A and hydrophobic B blocks in an aqueous solution. The vesiculation pathway consists of several intermediate structures, such as an interconnected network of copolymer aggregates, a cage of cylindrical micelles, and a lamellar cage. The cage-to-vesicle transition occurs at a constant aggregation number and practically eliminates the hydrophobic interfacial area between the B block and solvent. Molecular reorganization underlying the sequence of morphology transitions from a cage-like aggregate to a vesicle is nearly isentropic. The end-to-end distances of isolated copolymer chains in solution and those within a vesicular assembly follow lognormal probability distributions. This can be attributed to the preponderance of folded chain configurations in which the two hydrophobic end groups of a given chain stay close to each other. However, the probability distribution of end-to-end distances is broader for chains within the vesicle as compared with that of a single chain. This is due to the swelling of the folded configurations within the hydrophobic bilayer. Increasing the hydrophobicity of the B block reduces the vesiculation time without qualitatively altering the self-assembly pathway. [ABSTRACT FROM AUTHOR]

Amphiphilic block copolymers of poly(ethylene glycol) (PEG) and poly(vinylidene fluoride) (PVDF) were successfully synthesized by growing poly(vinylidene fluoride) on PEG‐chain transfer agent (PEG‐macro‐CTA) using reversible addition–fragmentation chain transfer (RAFT) polymerization. MeO‐PEG‐XA, and XA‐PEG‐XA macro‐CTAs (XA refers to the xanthate moiety), synthesized by esterification of MeO‐PEG‐OH (20,000 g mol−1) and HO‐PEG‐OH (20,000 g mol−1) with 2‐bromopropionyl bromide followed by reaction with potassium ethyl xanthate, were used to synthesize MeO‐PEG‐b‐PVDF and PVDF‐b‐PEG‐b‐PVDF, respectively. The synthesized macro‐CTAs and block copolymers were characterized by NMR (1H, 13C and 19F), FTIR, and SEC. Furthermore, the PVDF/PEG block copolymer formation was proved by 1H DOSY NMR. The thermal properties were determined by TGA and DSC. The crystallinity and electroactive phases were revealed by XRD and FTIR. The size and shape of self‐assembled block copolymers in DMF/water mixtures were determined by DLS, TEM and critical micelle concentration with fluorescence spectroscopy. The influence of molecular weight and PVDF content on the properties of copolymers is discussed. [ABSTRACT FROM AUTHOR]

In this work, the question of the influence of the counterion size on the self-assembly in melts of diblock copolymers with one charged block was studied using coarse-grained molecular dynamics simulations. It was assumed that the blocks were fully compatible, i.e., the Flory–Huggins parameter χ between them was equal to 0. Due to the presence of correlation attraction (electrostatic cohesion) between the charged species, the systems with all types of counterions underwent transitions to ordered states, forming various morphologies, including lamellae, perforated lamellae, and hexagonally packed cylinders. Phase diagrams were constructed by varying the chain composition fc and locating the order–disorder transition positions in terms of the electrostatic strength parameter λ (dimensionless Bjerrum length). Despite having a rather large ion size mismatch, the systems with smaller counterions demonstrated an even better tendency to form microphase separated states than the systems with larger ones. It was found that the differences between the phase diagrams of the systems with different counterions can be roughly rationalized by using coordinates (volume fraction of the charged block φc—modified interaction parameter λ*). The latter parameter assumes that the electrostatic energy is simply inversely proportional to the characteristic distance between the ions of different signs. Such an approach appeared to be rather effective and allowed the diagrams obtained for different counterion sizes to almost coincide. The results of this work suggest that the counterion size can be used as a tool to control the system morphology as well as the effective incompatibility between the blocks. [ABSTRACT FROM AUTHOR]

Well-tempered metadynamics (WTMD) is applied to field-theoretic simulations (FTS) to locate the order–disorder transition (ODT) in incompressible melts of diblock copolymer with an invariant polymerization index of N ̄ = 1 0 4 . The polymers are modeled as discrete Gaussian chains with N = 90 monomers, and the incompressibility is treated by a partial saddle-point approximation. Our implementation of WTMD proves effective at locating the ODT of the lamellar and cylindrical regions, but it has difficulty with that of the spherical and gyroid regions. In the latter two cases, our choice of order parameter cannot sufficiently distinguish the ordered and disordered states because of the similarity in microstructures. The gyroid phase has the added complication that it competes with a number of other morphologies, and thus, it might be beneficial to extend the WTMD to multiple order parameters. Nevertheless, when the method works, the ODT can be located with impressive accuracy (e.g., ΔχN ∼ 0.01). [ABSTRACT FROM AUTHOR]

Urethane acrylate (UA) was synthesized from various di-polyols, such as poly(tetrahydrofuran) (PTMG, Mn = 1000), poly(ethylene glycol) (PEG, Mn = 1000), and poly(propylene glycol) (PPG, Mn = 1000), for use as a polymer binder for paint. Polymethyl methacrylate (PMMA) and UA were blended to form an acrylic resin with high transmittance and stress-strain curve. When PMMA was blended with UA, a network structure was formed due to physical entanglement between the two polymers, increasing the mechanical properties. UA was synthesized by forming a prepolymer using di-polyol and hexamethylene diisocyanate, which were chain structure monomers, and capping them with 2-hydroxyethyl methacrylate to provide an acryl group. Fourier transform infrared spectroscopy was used to observe the changes in functional groups, and gel permeation chromatography was used to confirm that the three series showed similar molecular weight and PDI values. The yellowing phenomenon that appears mainly in the curing reaction of the polymer binder was solved, and the mechanical properties according to the effects of the polyol used in the main chain were compared. The content of the blended UA was quantified using ultravioletvisible spectroscopy at a wavelength of 370 nm based on 5, 10, 15, and 20 wt%, and the shear strength and tensile strength were evaluated using specimens in a suitable mode. The ratio for producing the polymer binder was optimized. The mechanical properties of the polymer binder with 5–10 wt% UA were improved in all series. [ABSTRACT FROM AUTHOR]

Hierarchical self-assembly with long-range order above centimeters widely exists in nature. Mimicking similar structures to promote reaction kinetics of electrochemical energy devices is of immense interest, yet remains challenging. Here, we report a bottom-up self-assembly approach to constructing ordered mesoporous nanofibers with a structure resembling vascular bundles via electrospinning. The synthesis involves self-assembling polystyrene (PS) homopolymer, amphiphilic diblock copolymer, and precursors into supramolecular micelles. Elongational dynamics of viscoelastic micelle solution together with fast solvent evaporation during electrospinning cause simultaneous close packing and uniaxial stretching of micelles, consequently producing polymer nanofibers consisting of oriented micelles. The method is versatile for the fabrication of large-scale ordered mesoporous nanofibers with adjustable pore diameter and various compositions such as carbon, SiO2, TiO2 and WO3. The aligned longitudinal mesopores connected side-by-side by tiny pores offer highly exposed active sites and expedite electron/ion transport. The assembled electrodes deliver outstanding performance for lithium metal batteries. [ABSTRACT FROM AUTHOR]

Methoxy poly(ethylene glycol)-block-poly(L-lactide) (MPEG-b-PLLA) has a wide range of applications in pharmaceuticals and biology, and its structure and morphology have been thoroughly studied. In the experiment, we synthesized MPEG-b-PLLA with different block lengths using the principle of ring-opening polymerization by controlling the amount of lactic acid added. The thermodynamic properties of copolymers and the crystallization properties of blends were studied separately. The crystallization kinetics of PDLA/MPEG-b-PLA and PLLA/MPEG-b-PLA composite films were studied using differential scanning calorimetry (DSC). The results indicate that the crystallization kinetics of composite films are closely related to the amount of block addition. The crystallinity of the sample first increases and then decreases with an increase in MPEG-b-PLLA content. These results were also confirmed in polarized optical microscope (POM) and wide-angle X-ray diffraction (WAXD) tests. When 3% MPEG-b-PLLA was added to the PDLA matrix, the blend exhibited the strongest crystallization performance. [ABSTRACT FROM AUTHOR]