Polymer Phase Research Articles

Mixed-Solvent-Induced Phase Separation Enables Anisotropy and Strengthening of Hydrogels Composed of Flexible Network Chains.

Achieving anisotropy in hydrogels is key to replicating the structural and mechanical properties of biological tissues. However, inducing anisotropy in hydrogel systems composed solely of flexible amorphous polymers is challenging, as these polymers typically exhibit thermally unstable anisotropic states, i.e., they are easy to disorient. In this study, a mixed-solvent-induced phase-separation approach to stabilize the orientation of such hydrogel networks after pre-stretching is introduced. Using polyacrylamide, a flexible polymer with a persistence length on the order of 10-1nm, as a model system, it is demonstrated that phase separation in a mixed solvent leads to the formation of dense and dilute polymer phases, with the dense phase effectively locking the anisotropy through robust inter- and intra-polymer interactions. A series of characterizations confirm that partial orientation can be preserved in the prestretched, phase-separated gel upon relaxation, resulting in significant mechanical enhancement along the orientation direction, including improvements in fracture stress, Young's modulus, and fracture toughness. The generality of this method, showing its effectiveness in other hydrogel systems and its adaptability to different solvent combinations is also validated. This work presents an unconventional strategy for preparing anisotropic hydrogels that typically struggle to maintain structural integrity.

Deriving High-Energy-Density Polymeric Nitrogen N10 from the Host–Guest ArN10 Compound

Discovering stable polymeric nitrogen phases and exploring their properties are crucial for energy storage and conversion, garnering significant attention. In this study, we investigate the formation possibility of a stable compound between Ar and N2 through ab initio calculations under low-pressure conditions (0–100 GPa). The novel super nitride, Imm2 ArN10, is designed to demonstrate robust thermodynamic stability under high pressures (91 GPa) and showcase the unique host–guest structure, in which guest atoms (Ar) are trapped inside the host polymeric N10. Significantly, given the weak interaction between Ar and N atoms and a channel parallel to the c-crystallographic axis in ArN10, we propose a novel method to stabilize the previously unknown polymeric nitrogen structure, Imm2-N10, by removing the guest argon atoms from the natural channels of ArN10. Imm2 ArN10 and N10 are thermodynamically and dynamically stable, with energy densities of 9.1 kJ g−1 and 12.3 kJ g−1, respectively—more than twice that of TNT. Additionally, ArN10 and N10 stand out as leading green energetic materials, boasting a superior explosion velocity of 17.56 km s−1 and a detonation pressure of 1712 kbar, surpassing that of TNT. These findings significantly impact on the creation of pure nitrogen frameworks through chemical reactions involving inert elements under high pressure.

Optimizing the mechanical performance of nacre‐like hydroxyapatite/polymethylmethacrylate–polyacrylic acid composites with apatite‐wollastonite

AbstractBiomimetic materials inspired by the hierarchical structure of nacre offer promising opportunities to enhance the mechanical strength and toughness of load‐bearing bone implants. This study investigates the incorporation of apatite‐wollastonite (AW) into nacre‐like hydroxyapatite (HA)/polymethylmethacrylate–polyacrylic acid (PMMA–PAA) composites to improve their mechanical properties. The composite mimics the natural nacre structure, featuring a brick‐and‐mortar architecture where ceramic components form the “bricks,” and the polymer phase acts as the “mortar.” The results showed that adding AW significantly increased the density of the ceramic scaffolds and improved the sinterability of HA. However, at higher AW concentrations (e.g., 20 wt%), excessive grain growth was observed, which could negatively affect the composite's mechanical properties. The best mechanical performance was achieved at 15 wt% AW, which enhanced the sintering process and reinforced the HA through the formation of a stronger wollastonite phase, as revealed by x‐ray diffraction analysis. Mechanical testing showed that the composite with 15 wt% AW exhibited superior properties, with flexural strength increasing from 158.2 ± 7.1 MPa (for HA/PMMA–PAA) to 188.7 ± 6.2 MPa (for AW–HA/PMMA–PAA). Fracture toughness also improved significantly, from 5.2 to 10.2 MPa m1/2. In addition to improved flexural strength and fracture toughness, the composite's Young's modulus of 28.5 ± 1.6 GPa closely matched that of cortical bone, reducing the risk of stress shielding, a common issue with commercial implants. Acellular bioactivity tests demonstrated the formation of a biologically relevant apatite layer on the composite surface, indicating its potential to promote osseointegration. Cytocompatibility assays confirmed favorable cell proliferation and viability, supporting its suitability for clinical applications. In summary, the addition of AW enhanced sinterability and introduced a stronger wollastonite phase within the HA ceramic layer, leading to improved strength and toughness of the nacre‐like HA/PMMA–PAA composites. However, there was an optimal AW concentration that balanced superior mechanical properties with controlled grain growth. The bioactive and cytocompatible composites showed great promise as candidates for next‐generation load‐bearing bone implants.

Protein Orientation and Polymer Phase Separation Induced by Poly(methyl methacrylate) Tacticity.

Stereochemistry may affect the physicochemical and biological properties of polymer films that are important for their applications, including substrates for the fabrication of protein microarrays. In this study, we investigated the effect of poly(methyl methacrylate) (PMMA) tacticity on the interaction of polymer thin films with proteins and on the phase separation process in blends with poly(tert-butyl methacrylate) (PtBMA). Thin films of isotactic, atactic, and syndiotactic PMMA were studied for topography, surface chemistry, and protein adsorption. Secondary ion mass spectrometry and contact angle measurements revealed a lower surface exposure of polar ester functional groups for iso-PMMA, resulting in the reduced adsorption of albumin and fibrinogen proteins. We also showed that changes in surface chemistry alter the orientation of proteins adsorbed on iso-PMMA through hydrophobic and electrostatic interactions. In addition, blends composed of PMMA and PtBMA, both of different tacticities, were investigated in terms of protein microarray fabrication. The two-dimensional domain structure was obtained by a phase separation process for at-PtBMA blends prepared on silicon substrates modified with amino-silane. Finally, for an isotropic and regular polymer pattern of iso-PMMA/at-PtBMA, the possibility of protein microarray formation on this blend was demonstrated, showing selective adsorption to PtBMA domains and perfect mirroring of the polymer patterns.

Phase-field modeling of interfacial fracture in quasicrystal composites

Phase-field modeling of interfacial fracture in quasicrystal composites

Pickering polymerized high internal phase emulsions: Fundamentals to advanced applications.

Pickering-polymerized high internal phase emulsions have attracted attention since their successful first preparation 15years ago, primarily due to their large pores and potential for functionalization during production. This review elucidates the fundamental principles of Pickering emulsions, Pickering HIPEs, and Pickering PolyHIPEs while comparing them to conventional surfactant-stabilized counterparts. The morphology of Pickering PolyHIPEs, with particular emphasis on methods for achieving interconnected structures, is explored and critically assessed. Lastly, the mechanical properties and diverse applications of these materials are reviewed, highlighting their use as catalytic supports and sorbent materials. The study aims to guide both new and experienced researchers in the field by comprehensively addressing the current potential and challenges of Pickering PolyHIPEs. Once the mystery behind the closed cellular pores of Pickering PolyHIPEs is resolved, these materials are expected to become more popular, particularly in applications where mass transfer is critical, such as tissue engineering.

Development of hot melt extruded Polycaprolactone (PCL) matrices for an oral ultra-long-lasting delivery of Galantamine for Alzheimer’s disease therapy

Development of hot melt extruded Polycaprolactone (PCL) matrices for an oral ultra-long-lasting delivery of Galantamine for Alzheimer’s disease therapy

Study of the influence of ultra-high molecular weight polyethylene and high-density polyethylene on the properties and structure of ethylene propylene diene monomer rubber

Objectives. The study set out to examine the impact of pre-mixed ultra-high molecular weight polyethylene (UHMWPE) and high-density polyethylene (HDPE) on a range of properties and structural characteristics of SKEPT-50 ethylene propylene diene monomer (EPDM) rubber.Methods. The production of rubber mixtures involved the pre-mixing of rubber with UHMWPE and HDPE in a Brabender PL 2200-3 plasti-corder chamber (Germany) at a temperature of 160°C, for a period of 6 min, and with a rotor speed of 60 rpm. The polyethylene constituents were incorporated into the rubber compound at concentrations of 5, 10, and 15 pts. wt. The subsequent introduction of the principal constituents of the rubber mixture was conducted in an SYM laboratory mill (China) for a period of 30 min at a temperature of no more than 100°C. The vulcanization of the samples was conducted in an Y1000D vacuum hydraulic press (China) at a temperature of 185°C for a period of 35 min. The investigation of vulcanization and physical and mechanical properties was conducted in accordance with the established protocols. The analysis of the rubber supramolecular structure was conducted using a JEOL JSM-6840 LV scanning electron microscope (Japan).Results. The results demonstrate that an increase in the proportion of HDPE and UHMWPE to 15 pts. wt leads to a notable enhancement in the hardness of the rubbers by 10 and 5 Shore A units, respectively. The frost resistance coefficient at −45°C demonstrates an increase with the incorporation of 10 pts. wt of HDPE to reach a value of 0.229, and a further increase with the incorporation of 15 pts. wt of UHMWPE to reach a value of 0.260. The degree of swelling of rubbers in a DOT-4 brake fluid environment is observed to decrease to 13% for rubbers with HDPE and 19% with UHMWPE. The degree of swelling of rubbers in the DOT-4 brake fluid environment is observed to decrease to 13% for rubbers with HDPE and 19% with UHMWPE. While an increase in the HDPE content results in a 5% increase in volumetric wear, an increase in the UHMWPE content is associated with a 45% decrease in volumetric wear. The introduction of UHMWPE was observed to result in the formation of inclusions of varying shapes and sizes within a range of 50–100 µm. The transition zone between UHMWPE and rubber is characterized by a smooth surface. No evidence of cracks or micro-tears between the polymer phases, which could potentially form during low-temperature splitting, was observed. This finding indicates the presence of favorable interfacial interactions, which can be linked to the observed enhancements in resistance to aggressive liquids and abrasion, as well as the improved tensile frost resistance coefficient. The supramolecular structure of rubber samples combined with HDPE is more pronounced and exhibits greater relief than that of the original rubber. This is indicative of a more uniform distribution within the matrix volume, which can be attributed to the high fluidity of the HDPE melt.Conclusions. Rubbers modified with UHMWPE, in comparison with HDPE, exhibit enhanced resistance to wear, oil, and frost, while maintaining their elastic and strength properties. It was established that rubber containing 15 pts. wt of UHMWPE exhibits optimal properties and can thus be recommended for use in sealing rubber products.

High Energy Storage Under the Regulation of Polymer Phase Structure.

Dielectric nanocomposites have garnered significant interest owing to their potential applications in energy storage. However, achieving high energy density (Ue) and charge/discharge efficiency (η) remains a challenge in their fabrication. In this paper, core-shell structured BaTiO3@Polyvinylpyrrolidone (BT@PVP) nanoparticles are prepared, and incorporated into a semi-crystalline polyvinylidene fluoride (PVDF) matrix. The BT@PVP/PVDF nanocomposite film loaded with 5vol.% BT@PVP nanoparticles show a maximum Ue of 18.39 Jcm-3 at 458 MVm-1, which is almost 4 and 9 times greater than those of BT/PVDF (5.14 Jcm-3 at 303 MVm-1) and biaxially oriented polypropylene (BOPP) (2 Jcm-3 at 640 MVm-1), respectively. Notably, the highest charge/discharge efficiency of 79.80% has been achieved so far for ferroelectric inorganic-filled PVDF composites. The reason why there are such excellent performances is mainly because of the interface coupling of inorganic-organic nanocomposite film and PVDF β phase transition with coating and extrusion of PVP molecules and large polarization of BT respectively. This research introduces a convenient and effective approach to designing high-performance dielectric polymer nanocomposites.

Understanding the influence of mixing on a solvent‐free emulsification process for highly viscous polymers using a twin‐screw extruder

AbstractTwin‐screw extrusion with its capacity to handle high‐viscosity polymers can be used to create a continuous emulsification process without solvents but presently this approach is challenging to make stable due to the uncertain role of mixing. To address this challenge, the influence of mixing was studied by examining several process‐ and material‐related factors in this work. From the results, the kinetics of interfacial area growth between the polymer and water phases was described in terms of nucleation, propagation and termination stages, with the latter stage ideally corresponding to the dilution zone where phase inversion occurs. The nucleation stage was found to be strongly dependent on early water solubilization in the polymer, controlled by the acid number of the polyester, to determine the initial water fraction feasibly dispersed within this oil‐like phase prior to the dilution zone (referred to as the emulsion boundary). Propagation was influenced by surfactant concentration and strongly affected by residence time, with a longer dispersion zone or lower feed rate allowing for higher cumulative shear strain and a greater chance to completely emulsify the polymer. Ideally, these kinetic stages correspond with the physical zones of the machine else varying degree of emulsification are shown to result.Highlights Early water solublization in the polyester is dependent on the acid number Higher residence time impacted mixing more than shear rate Water fraction dispersible in the melt was strongly affected by mixing Emulsion boundary was adjustable by amount of mixing and surfactant

A critical review on Li-ion transport, chemistry and structure of ceramic-polymer composite electrolytes for solid state batteries.

In the transition to safer, more energy-dense solid state batteries, polymer-ceramic composite electrolytes may offer a potential route to achieve simultaneously high Li-ion conductivity and enhanced mechanical stability. Despite numerous studies on the polymer-ceramic composite electrolytes, disagreements persist on whether the polymer or the ceramic is positively impacted in their constituent ionic conductivity for such composite electrolytes, and even whether the interface is a blocking layer or a highly conductive lithium ion path. This lack of understanding limits the design of effective composite solid electrolytes. By thorough and critical analysis of the data collected in the field over the last three decades, we present arguments for lithium conduction through the bulk of the polymer, ceramic, or their interface. From this analysis, we can conclude that the unexpectedly high conductivity reported for some ceramic-polymer composites cannot be accounted for by the ceramic phase alone. There is evidence to support the theory that the Li-ion conductivity in the polymer phase increases along this interface in contact with the ceramic. The potential mechanisms for this include increased free volume, decreased crystallinity, and modulated Lewis acid-base effects in the polymer, with the former two to be the more likely mechanisms. Future work in this field requires understanding these factors more quantitatively, and tuning of the ceramic surface chemistry and morphology in order to obtain targeted structural modifications in the polymer phase.

Self-limiting selective phase separation of graphene oxide and polymer composite solution.

Homogeneous mixtures undergo phase separation to generate rich heterogeneous structures as well as enable complex physiological activity and delicate design of artificial materials. Beyond free space, the strong coupling between migrating components and spatial confinement plays a crucial role in determining the essential spatial compartment of phase separation, warranting further continuous exploration. Herein, we report the selective phase separation (SPS) behavior of polymers under a mobile two-dimensional (2D) confinement by graphene oxide (GO) sheets. The selection of a poor solvent triggers the occurrence of SPS in a homogeneous solution of GO and polymers. We reveal that the self-limiting spatial confinement of GO sheets leads to the migration of polymers to form independent and continuous phase in 2D confinement. We examine the quantitative rule of size and continuity of polymer phases in correlation with solvent properties and solute constitutes. The observed SPS allows the facile generation of heterogenous nanostructures in GO/polymer composites. We initiate a SPS wet-spinning to fabricate radial heterogenous fibrous graphene composite fibers with ultrahigh elongation at break and superior flexibility. The observed SPS can inspire more exceptional phase separation behaviors under mobile 2D confinement and offers a facile method to delicately design 2D heterogeneous nanostructured materials.

The effect of selective surface interaction on polymer phase separation with explicit polydispersity during polymerization.

In polymerization-induced phase separation, the impact of polymer-substrate interaction on the dynamics of phase separation for polymer blends is important in determining the final morphology and properties of polymer materials as the surface can act as another driving force for phase separation other than polymerization. We modify the previously-developed polymerizing Cahn-Hilliard (pCH) method by adding a surface potential to model the phase separation behavior of a mixture of two species independently undergoing linear step-growth polymerization in the presence of a surface. In our approach, we explicitly model polydispersity by separately considering different molecular-weight components with their own respective diffusion constants, and with the surface potential preferentially acting on only one species. We first show that the surface potential induces faster phase separation of smaller molecules at early stages before the degree of polymerization becomes large enough to drive bulk phase separation. This model is then used to investigate the degree of anisotropic ordering in a direction perpendicular to the surface over various polymerization rates k̃ and strengths of the potential Ṽ. We find that at low k̃, smaller molecules have sufficient time to diffuse and accumulate at the potential surface, resulting in richer production of heavier polymers at the surface without the need for larger polymers to diffuse on their own toward the surface. Conversely, at high k̃, larger polymers first evenly accumulate throughout the system before undergoing phase separation; the concentration wave initiated from the potential surface then propagates into the bulk, resulting in anisotropic phase separation.

Covalent organic frameworks hybridized polymeric high internal phase emulsions with amphiphilicity for extraction of trace bisamide insecticides in food samples.

Polymeric high internal phase emulsions decorated with covalent organic frameworks (polyHIPEs-COFs) were synthesized and used as the sorbent for cyantraniliprole and chlorantraniliprole. Pickering high internal phase emulsions stabilized by covalent organic frameworks solid particles and liquid surfactants (Span80 and polyvinylpyrrolidone) endow the composites with open-cell structures and superwettability. The amphiphilicity and open-cell structures enable rapid adsorption and desorption for cyantraniliprole and chlorantraniliprole, and the solid-phase extraction process can be completed in 5min. The adsorption efficiencies of polyHIPEs-COFs for cyantraniliprole and chlorantraniliprole are above 85.19%, but lower than 10% for fenvalerate, anti-aphid, and chlorpyrifos, demonstrating the good adsorption selectivity for cyantraniliprole and chlorantraniliprole. The adsorption efficiencies of cyantraniliprole and chlorantraniliprole using a same polyHIPEs-COFs and five different batches of polyHIPEs-COFs range from 94.25 to 100.00%, revealing the good reproducibility of the sorbent. In addition, the polyHIPEs-COF-based solid-phase extraction combined with high-performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for determination of bisamide insecticides in vegetable (eggplants, tomatoes, and peppers) samples. Results showed that the method was feasible to determinethe cyantraniliprole and chlorantraniliprole in real vegetable samples with a linear range of 0.012-1.2μg/kg and limits of detection of 0.0075-0.0090μg/kg. The recoveries of cyantraniliprole and chlorantraniliprole spiked in vegetable samples ranged from 85.00 to 100.00% with relative standard deviations less than 3.52%. The study indicates the feasibility of amphiphilic polyHIPEs-COFs in extraction and enrichment of bisamide insecticides from vegetable samples for HPLC-UV analysis.

Assessing the Biodegradation of Low-Density Polyethylene Films by Candida tropicalis SLNEA04 and Rhodotorula mucilaginosa SLNEA05

Environmental pollution resulting from the accumulation of plastic waste poses a major ecological challenge. Biodegradation of these polymers relies on microorganisms capable of decomposing them, generally through the biodeterioration, biofragmentation, assimilation, and mineralization stages. This study evaluates the contribution and efficacy of indigenous soil yeasts isolated from a northeastern Algerian landfill in degrading low-density polyethylene (LDPE) plastic bag films. Candida tropicalis SLNEA04 and Rhodotorula mucilaginosa SLNEA05 were identified through internal transcribed spacer (ITS) and large subunit ribosomal RNA gene sequencing. These isolates were then tested for their ability to biodegrade LDPE films and utilized as the sole carbon source in vitro in a mineral salt medium (MSM). The biodegradation effect was examined using scanning electron microscopy (SEM), attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy, and X-ray diffraction (XRD). After 30 days of incubation at 25 °C, a significant weight loss was observed compared to the control for both cultures: 7.60% and 5.53% for C. tropicalis and R. mucilaginosa, respectively. SEM analysis revealed morphological alterations, including cracks and holes, ATR-FTIR detected new functional groups (alcohols, alkynes, aldehydes, alkenes and ketones), while XRD identified changes in the polymer crystallinity and phase composition. These findings underscore the potential of the two yeast isolates in LDPE biodegradation, offering promising insights for future environmental applications.

Hexagonal Boron Nitride as a Two-Dimensional Surfactant: Low-Density Flame-Resistant Composites Based on Boron Nitride Exfoliated by an Interface Trapping Technique.

Hexagonal boron nitride (hBN) is a two-dimensional material isoelectric to graphene. It has a hexagonal structure with alternating boron and nitrogen atoms and is electrically insulating, thermally conductive, and chemically inert. However, like graphene, its use as a functional nanofiller requires exfoliation. Here, we present a method for exfoliating and dispersing hexagonal boron nitride (hBN) sheets within a polymer matrix. This is achieved by a solvent interface trapping method (SITM), where hBN exfoliates and spreads at a high-energy oil/water interface, separating the two phases and lowering the system's free energy. hBN thus acts as a surfactant, allowing us to form stable water-in-oil emulsions stabilized by films of overlapping hBN sheets. Polymerizing the continuous oil phase results in polymerized high internal phase emulsions (polyHIPE), with the foam cells lined with hBN. In the investigation presented here, we use acoustic spectroscopy, optical and electron microscopy, and image analysis to study the emulsion and polyHIPE formation mechanisms. We find that the amount of hBN used, the flake size of the hBN, the mixing time, the type of initiator used, and the oil-to-water ratio all play a role in the morphology of the final polyHIPE. Lastly, we demonstrate the flame-retardant properties of the hBN polyHIPEs and show that, at 1% loadings, the presence of hBN prevents dripping and relighting of the composites, even when the material is heated to a red glow.

Dynamic reaction of slag-based geopolymer with brick powder: insights from acoustic emission, heat flow, and relaxation characteristics

Dynamic reaction of slag-based geopolymer with brick powder: insights from acoustic emission, heat flow, and relaxation characteristics

Tailoring the surface of a polymeric membrane with a thin-layer Nafion membrane: Construction of an anti-surfactant solid-contact ion-selective electrode

Tailoring the surface of a polymeric membrane with a thin-layer Nafion membrane: Construction of an anti-surfactant solid-contact ion-selective electrode

A Multiscale Perspective on Chromatin Architecture through Polymer Physics.

The spatial organization of chromatin within the eukaryotic nucleus is critical in regulating key cellular functions, such as gene expression, and its disruption can lead to disease. Advances in experimental techniques, such as Hi-C and microscopy, have significantly enhanced our understanding of chromatin's intricate and dynamic architecture, revealing complex patterns of interaction at multiple scales. Along with experimental methods, physics-based computational models, including polymer phase separation and loop-extrusion mechanisms, have been developed to explain chromatin structure in a principled manner. Here, we illustrate genome-wide applications of these models, highlighting their ability to predict chromatin contacts across different scales and to spread light on the underlying molecular determinants. Additionally, we discuss how these models provide a framework for understanding alterations in chromosome folding associated with disease states, such as SARS-CoV-2 infection and pathogenic structural variants, providing valuable insights into the role of chromatin architecture in health and disease.

Improving Thermo-Sealing of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Blending with Polycaprolactone.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable biopolymer from the PHAs family that has potential to replace conventional plastics and reduce plastic pollution. However, PHBV has thermo-sealability issues, making it challenging to use for bags. Blending it with polycaprolactone (PCL) could address this but may alter the barrier properties of the films, affecting their effectiveness as food packaging material. This study examined the properties and heat-sealing capacity of PHBV/PCL blend films (ratios: 60/40, 50/50, and 40/60), obtained by melt blending and compression moulding. Both polymers are immiscible and were in separated phases; the continuous phase was PHBV in the 60/40 blend and PCL in the 40/60 blend, while the 50/50 sample exhibited interpenetrating bicontinuous phases of both polymers. The permeability to water vapour, oxygen, and D-limonene increased as the PCL content rose, especially when it formed the continuous phase in the matrix. The elastic modulus and resistance to break decreased, while extensibility increased, more markedly when PCL was the continuous phase. However, the continuity of PCL phase provided the films with better thermal adhesion and seal strength. The 50/50 blend showed the best balance between heat sealability and barrier properties, making it the most suitable for food packaging in sealed bags.