Polymer Swelling Research Articles

HRMAS NMR for Studying Solvent-Induced Mobility of Polymer Chains and Metallocene Migration Into Low-Density Polyethylene (LDPE).

HRMAS (high-resolution magic angle spinning) nuclear magnetic resonance (NMR) spectroscopy of low-density polyethylene (LDPE) affords 1H and 13C NMR spectra with superior resolution. For acquiring HRMAS NMR spectra, the polymer is first swollen with representative organic solvents. Then, the samples are measured with a conventional solid-state NMR spectrometer in the wideline mode or at the low spinning speed of 2 kHz. Anisotropic interactions like CSA (chemical shift anisotropy) and dipolar interactions are reduced due to the additional mobility of the polymer chains in the presence of the solvent within the polymer network. The combined effect of this mobility and MAS leads to signals with substantially reduced halfwidths as compared to classic MAS of the dry polymer. With HRMAS, all signals of the polymer become visible, and the spectra can be used for a quick and easy assessment of the polymer swelling behavior in diverse solvents. Being able to characterize polymers on the molecular level, and identifying the solvents that penetrate the polymer network best, enables the study of post-synthesis modifications of the polymers. It is demonstrated by paramagnetic HRMAS that the metallocene nickelocene (Cp2Ni) penetrates the LDPE network along with the solvent and is homogeneously dispersed in the polymer. SEM images prove that the structure of the polymer is not altered by the presence of a solvent and Cp2Ni. The impact of the paramagnetic Cp2Ni on the 1H signal halfwidth and T1 time of LDPE is studied. HRMAS allows a quick assessment of metal complexes regarding their ability to penetrate the LDPE network and therefore supports future studies of catalytic polymer degradation.

Colorimetric Fabry-Pérot Sensor with Hetero-Structured Dielectric for Humidity Monitoring.

A full-color colorimetric humidity sensor with high brightness is proposed by using a hetero-structured dielectric film in a metal-insulator-metal (MIM) resonator. A humidity-responsive polymer is designed to graft on top of a metal-organic frameworks (MOFs) thin film (MOFs-Polymer) as insulator layer in the resonator. Programmable tuning of reflected color is achieved by controlling the polymer thicknesses, and finite difference time domain simulation of light-matter interactions at subwavelength scales proves the dependence of the reflected wavelength on dielectric layer thickness of the resonator. Vivid full-color changing is realized during tracking humidity process due to swelling of the stimuli-responsive polymer. Ultrafast response (≈0.75 s) is achieved for tracking trace H2O from H2O/methanol mixture, which is ≈104 faster than that of the pure polymer-based MIM resonator. Meanwhile, the study observes significant spectral redshift because the porous MOFs film facilitates the preconcentration of external stimulus and improves the detection sensitivity of the resonator. Further, double-channel anti-counterfeiting multiplexing imaging is devised on the MIM resonator by photomask technology. Patterned encoding for security label is achieved on the MIM resonator by engineering humidity-tunable pixels of Au/MOFs-Polymer/Au and humidity-invalid pixels of Au/MOFs/Au.

Absorption and Release mechanism of superabsorbent polymers and its impact on shrinkage and durability of internally cured concrete – A review

Superabsorbent polymers (SAP) are considered as a promising assortment of chemical admixtures which present novel prospects for influencing the properties of cementitious materials in the fresh, setting, and hardened states. However, the diversity of commercial SAP, especially in terms of monomers, crosslinking agents, and synthesis methods, still poses many obstacles in their large-scale application. Therefore, this review aims to shed light on intrinsic absorption and release mechanism of various SAP and its impact on rheological properties, mechanical properties, shrinkage properties, and durability for cementitious materials. Our research findings indicate significant differences in the water absorption and release mechanisms between ionic and non-ionic SAP. The swelling of non-ionic SAP is dependent on the osmotic pressure formed between the polymer network and the solution. In contrast, ionic SAP not only exhibits osmotic properties but also generates charged hydrophilic groups in solution, which is a crucial factor contributing to polymer swelling. The water absorption characteristics of SAP facilitate the regulation of early cement matrix hydration and ensure the long-term stability of the concrete structure. These attributes are crucial for maintaining stable development in cement hydration and ensuring the overall structural integrity over time. The knowledge gleaned from this review offers a robust framework for the further research work on SAP and serves as support for practical application of internally cured concrete in construction engineering that need to withstand challenging environmental conditions.

A Total Internal Reflection Microscopy (TIRM)-Based Approach for Direct Characterization of Polymer Brush Conformational Change in Aqueous Solution.

This study presents a novel approach utilizing total internal reflection microscopy (TIRM) to effectively characterize the swelling and collapse of polymer brushes in aqueous solutions. Zwitterionic poly(carboxybetaine methacrylate) (PCBMA) and nonionic poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) brushes are chosen as model systems. By investigation of an intriguing theory-experiment discrepancy observed during the measurement of near-wall hindered diffusion, valuable insights into the compressibility of polymer brushes are obtained, revealing their conformational information in aqueous solution. The results demonstrate that zwitterionic PCBMA brushes exhibit minimal antipolyelectrolyte effects in 0.1-10 mM NaCl solution but undergo significant swelling with increasing pH. On the other hand, nonionic POEGMA brushes exhibit similar responses to ionic strength as weak polyelectrolyte brushes. These unexpected findings enhance our understanding of polymer brushes beyond classical theories. The TIRM-based approach proves to be effective for characterizing polymer brushes and other soft nanomaterials.

Modified Release Interpenetrating Polymeric Network Hydrogel Beads of Montelukast Sodium Via Box Behnken Design

Background: Interpenetrating Polymeric Networks (IPN) are cross-linked polymeric alloys developed when two or more cross-linked polymers inter-penetratingly entangle. Interpenetrating polymeric networks possess several benefits including stability, biocompatibility, biodegradability, high swelling ability, and modified release efficiency. Aim: The aim of this study is to design stable, control-released montelukast sodium-loaded IPN hydrogel beads as a promising approach toward drug delivery. Objective: The goal of the present work was to develop Chitosan (swellable polymer) and glutaraldehyde (cross-linker) based modified (controlled) released montelukast sodium IPN hydrogel beads. Methods: The montelukast sodium IPN hydrogel beads were prepared via the precipitation method, and the final batch of IPN hydrogel beads was based on particle size, percent entrapment efficiency, area of swelling, and cumulative percent drug release using an overlay plot in Box-Behnken design. Compatibility studies (DSC, FT-IR) and microscopical observation (SEM) confirmed the compatibility and sphericity of the formulations. Results: The optimized (comprising 2.01% chitosan and 0.48% glutaraldehyde) IPN hydrogel beads having satisfactory particle size (817.76±54.49 μm), good entrapment efficiency (71.36±3.04%), and area of swelling (27.00±1.68 mm2) showed swelling and pH-dependent controlled montelukast release (92.96±1.05%) after 12 h with longer duration of action. Conclusion: The prepared montelukast sodium IPN hydrogel beads could be a potent control-released drug delivery vehicle.

Development of Gastroretentive Floating Combination Tablets Containing Amoxicillin Trihydrate 500 mg and Levofloxacin 125 mg for Eradicating Resistant Helicobacter pylori

Abstract: Background/Objectives: The aim of this work was to prepare and characterize gastroretentive floating combination tablets (GRCTs) containing 500 mg of amoxicillin trihydrate (AMX) and 125 mg of levofloxacin (LVX) that provide sustained drug release and stability at gastric pH levels for the eradication of resistant Helicobacter pylori. Method: GRCTs were prepared with low-density excipients and hydrophilic swellable polymers, including hydroxypropyl methylcellulose (HPMC) of various viscosities, polyethylene oxide (PEO), and carboxymethylcellulose (CMC), by the direct compression method. The prepared GRCTs were investigated and optimized in terms of pH stability, tablet hardness, floating lag time and total floating time, drug release rate, gel strength. Results: AMX and LVX in GRCT were stable at the HP eradication target pH above 4.0. The effervescent GRCT composition (AMX/LVX/HPMC [4000 cP]/CMC/microcrystalline cellulose/citric acid/sodium bicarbonate/calcium silicate/silicon dioxide/magnesium stearate = 500/125/50/50/125/40/60/30/10/10, w/w) yielded acceptable hardness (>6 kp), reduced floating lag time (<5 s), a long floating duration (>12 h), and sustained release rates of AMX and LVX (>90% until 12 h). This optimized GRCT had a gel strength of 107.33 ± 10.69 g and pH > 4.0, which maintained the tablets’ shape and AMX stability for 12 h. Conclusions: Collectively, the formulated effervescent GRCTs combining AMX and LVX represented a promising candidate dosage form for eradicating resistant H. pylori.

Reversible Modulation of Plasmonic Coupling of Gold Nanoparticles Confined within Swellable Polymer Colloidal Spheres.

Dynamic optical modulation in response to stimuli provides exciting opportunities for designing novel sensing, actuating, and authentication devices. Here, we demonstrate that the reversible swelling and deswelling of crosslinked polymer colloidal spheres in response to pH and temperature changes can be utilized to drive the assembly and disassembly of the embedded gold nanoparticles (AuNPs), inducing their plasmonic coupling and decoupling and, correspondingly, color changes. The multi-responsive colloids are created by depositing a monolayer of AuNPs on the surface of resorcinol-formaldehyde (RF) nanospheres, then overcoating them with an additional RF layer, followed by a seeded growth process to enlarge the AuNPs and reduce their interparticle separation to induce significant plasmonic coupling. This configuration facilitates dynamic modulation of plasmonic coupling through the reversible swelling/deswelling of the polymer spheres in response to pH and temperature changes. The rapid and repeatable transitions between coupled and decoupled plasmonic states of AuNPs enable reversible color switching when the polymer spheres are in colloidal form or embedded in hydrogel substrates. Furthermore, leveraging the photothermal effect and stimuli-responsive plasmonic coupling of the embedded AuNPs enables the construction of hybrid hydrogel films featuring switchable anticounterfeiting patterns, showcasing the versatility and potential of this multi-stimuli-responsive plasmonic system.

Experimentation, identification, and simulation of polymer swelling at extrusion die outlets

AbstractThe behavior of polyamide PA12 melt extrudates at die outlets is modeled to determine swelling process and rate. It is assessed as a function of imposed input parameters, process parameters, and die geometries. The modeling is carried out using Comsol Multiphysics® platform to simulate the swelling; in particular, its progression in time is investigated for different extrusion process parameters. The experimental swelling observed in extrusion lines tests is compared with the Tanner and Carreau‐Yasuda rheological models. A database is built up with all experiments carried out; the comparison between numerical and experimental results shows close agreement. A parametric analysis of the experimental and numerical swelling is performed. It confirms the important role of the die diameter on swelling rate, independently of shear rate. Increase in temperature lowers swelling rate at constant shear rates and geometric aspect ratio of the dies.Highlights Experimental and numerical study of polymer swelling at capillary die outlets. Behavior of PA12 polymer extrudate modeled to determine its swelling. Rheological models implemented to simulate the swelling phenomenon. Simulation results validated with experimental tests for two millimetric dies. Influence of die geometrical parameters investigated and justified.

Assessment of Binder Modification in Dry-Added Waste Plastic Modified Asphalt.

Plastic production has risen steadily, but recycling rates lag. Researchers are increasingly investigating the use of plastics in road construction, especially in terms of modifying asphalt with waste plastics. The dry process, which involves incorporating plastics into hot aggregates, is increasingly gaining traction as an alternative to the wet process, where plastics are added to hot bitumen. Past studies indicate enhanced asphalt mixture properties with the dry process, but there is debate about the role of waste plastics-whether they should be used as aggregates, fillers, or binder modifiers. This study explores the extent to which dry-added waste plastic modified the binder of the asphalt mixtures. Fluorescent microscopy and scanning electron microscopy revealed the impact of plastic on the binder, while image analysis quantified polymer swelling and dispersion in the binder matrix. It was concluded that when plastics are added to hot aggregates, they will act as binder modifiers. Lower plastic content and reduced polymer crystallinity led to increased polymer swelling and better dispersion in the mixture. This study recommends plastic inclusion of less than 2.5% (by volume) in the dry-added method since high plastic content leads to polymer agglomeration, especially for highly crystalline polymers. Additionally, mixes modified with amorphous plastics exhibited superior workability and performance compared to those modified with crystalline plastics. This study also suggests that using plastics to replace both bitumen and filler can improve cost efficiency, reduce the carbon footprint, and enhance the overall performance of the asphalt mixture.

The smart nanocarrier containing zein/starch co-biopolymers enhanced by graphitic carbon nitride; exploring opportunities in brain cancer treatment

In this investigation, we present an innovative pH-responsive nanocomposite designed to address challenges associated with using 5-Fluorouracil (5-FU) in cancer therapy. The nanocomposite containing zein (Z), starch (S), and graphitic carbon nitride (g-C3N4) macromolecules is synthesized by a water-in-oil-in-water (W/O/W) double emulsion technique, serving as a carrier for 5-FU. The S/Z hydrogel matrix's entrapment and loading efficiency are greatly improved by adding g-C3N4 nanosheets, reaching noteworthy values of 45.25 % and 86.5 %, respectively, for drug loading efficiency and entrapment efficiency. Characterization through FTIR and XRD validates the successful loading of 5-FU, elucidating the chemical bonding within the nanocomposite and crystalline characteristics. Structural analysis using FESEM, along with DLS and zeta potential measurements, reveals an average nanocomposite size of 193.48 nm, indicating a controlled structure, and a zeta potential of −42.32 mV, signifying a negatively charged surface. Studies on the in vitro release of drugs reveal that 5-FU is delivered more effectively and sustainably in acidic environments than in physiological circumstances. This highlights the fact that the created nanocarrier is pH-sensitive. Modeling release kinetics involves finding the right mathematical conditions representing underlying physicochemical processes. Employing curve-fitting techniques, predominant release mechanisms are identified, and optimal-fitting kinetic models are determined. The Baker kinetic model performed best at pH 7.4, indicating that the leading cause of the drug release was polymer swelling. In contrast, the Higuchi model was most accurate for drug release at pH 5.4, illuminating the diffusion and dissolution mechanisms involved in diffusion. To be more precise, the mechanism of release at pH 7.4 and 5.4 was anomalous transport (dissolution-controlled), according to the Korsmeyer-Peppas mathematical model. The pH-dependent swelling and degradation behavior of S/Z/g-C3N4@5-FU nanocomposite showed higher swelling and faster degradation in acidic environments compared to neutral conditions. Crucially, outcomes from the MTT test affirm the significant cytotoxicity of the 5-FU-loaded nanocomposite against U-87 MG brain cancer cells, while simultaneously indicating non-toxicity towards L929 fibroblast cells. These cumulative findings underscore the potential of the engineered S/Z/g-C3N4@5-FU as a productive and targeted therapeutic approach for cancer cells.

Kinetic Model of Fluorescein Release through Bioprinted Polylactic Acid Membrane.

Polylactic acid (PLA)-based cylindrical membranes for the controlled release of fluorescein sodium salt (FS) were prepared by bioprinting on systems with an initial FS concentration of 0.003763 gdm-3 and 37.63 gdm-3, and the drug release process was monitored in a bath at 37 °C. Photographs, acquired at regular intervals during the process, revealed marked osmotic swelling of the polymer. Osmotic swelling consists in the enlargement of the polymer structure and due to the influx of water molecules across the membrane. The cylindrical PLA membrane starts to significantly swell once a certain threshold range is crossed. Important amounts of FS can dissolve under these radically changed circumstances, and the dissolved FS molecules are mobile enough to diffuse out of the cylinder, thus allowing drug release. As a matter of fact, in this investigation, we ascertained that polymer swelling promotes the mass transport phenomenon by altering the conditions for drug dissolution and diffusion, hence facilitating FS release after a specific lag time. Furthermore, in order to compare the release kinetics, the half-release time, t0.5, was taken into consideration. The data of this study evidence that, while increasing the initial concentration of FS by three orders of magnitude, the time parameter, t0.5, is only reduced by 5/6. In addition, the yield of the release process is drastically reduced due to the strong aggregation ability of the dye. Finally, it is demonstrated that a compressed exponential kinetic model fits the experimental data well despite the varying physical conditions.

Pd(II)-Porphyrin-sensitized smart star polymer photocatalysts: A light-harvesting strategy using fluorescence resonance energy transfer effects

Photochemistry has become a popular topic in the field of sustainability. In particular, photocatalysts are a promising method to deal with environmental pollution, but only a few light sources with limited wavelengths are utilized to activate photosensitizers. Herein, we broaden the range of activation wavelengths of porphyrin-core amphiphilic star polymer photocatalysts by light harvesting. The coumarin moiety was polymerized from the porphyrin core while maintaining the amphiphilic microenvironment of the star polymer. The fluorescence resonance energy transfer (FRET) between porphyrin and coumarin leads to the activation of photocatalysts under both UV-A and UV-B light. Moreover, the copolymer sequence and polymer swelling effects on the FRET efficiency are discussed. The amphiphilic star block copolymer exhibited superior energy transfer efficiency in polar solvents, and its photocatalytic activity was evaluated via 2,5-dimethylfuran (2,5-DMF) photooxidation.

Bioinspired Colorimetric Double Inverse Opal Photonic Crystal Indicators for Ethanol Concentration Sensing in Fermentation Engineering.

Photonic crystal-based ethanol concentration indicators with rapid response and brilliant structural color output definitely take a place in colorimetric sensors. Here, based on the H-bond-regulated swelling of acrylate shape memory polymers (SMPs) and the solvent-induced structural color change of the double inverse opal photonic crystals (DIOPCs), new-type photonic crystals (PCs) colorimetric indicators were constructed, exhibiting a span of maximum reflection wavelength (λmax) up to ∼166 nm in response to alcohols with concentrations from 0 to 100 vol %. DIOPC indicators (DIOPCIs) show a rapid response to alcohols (<1.5 s) and output different structural colors (covering from blue to red). The colorimetric sensing mechanism includes the solvent-triggered recovery of the inverse opal skeleton, the cosolvency effect and H-bonds induced swelling/shrinkage of the polymer, the phase separation between polystyrene (PS) microsphere and polymer skeleton, and the light diffraction of DIOPCs. While ensuring a larger λmax span by regulating the H-bond interactions in polymer chains through acrylamide (AAm), AAm-modified DIOPCIs are sensitive to some specific ethanol concentrations. The real-time sensing of ethanol concentration during fermentation verified the practicability of DIOPCIs, thus establishing a visual model between structural color and corresponding fermentation kinetics. We envisage that the DIOPCIs will contribute to the intelligentization of the alcoholic fermentation and distillation industry.

Novel patient-specific gingival soft-tissue expander development for large bone defects using silicone 3D-printing technology

The current hydrogel self-inflating expander is limited by its volume and linear expansion rate, making it unsuitable for correcting patient-specific large mandibular bone defects in soft-tissue surgeries. This study devised a novel approach for crafting patient-specific gingival tissue expanders for large mandibular bone defects by employing silicone 3D-printing technology. The biocompatible and swellable polymer tablet was compressed and placed into a 3D-printed silicone membrane to evaluate its expansion capability. Two patient-specific large left and right mandibular bone defects with complex geometries were selected to generate defect expander models in a computer-aided design (CAD) software. The swellable tablets were enveloped in the 3D-printed silicone membranes to form soft-tissue expanders, which were then immersed in phosphate-buffered saline (PBS) for 6 weeks to observe their expansion. Results demonstrated that a slot-shaped silicone soft-tissue tablet attained an expansion volume of 1960 mm&amp;sup3;. A fourth-degree polynomial fitting curve illustrated slower expansion rates in the initial 2 weeks and achieved complete expansion in about 6 weeks. Patient-specific silicone expander testing indicated less than 2% error in the average expanded volumes of compared to CAD models. The cross-sectional profile of the soft-tissue expanders closely resembled the CAD model. This study demonstrated that biocompatible polymer could be utilized as swellable tablet material and enveloped within a 3D-printed silicone membrane to generate a novel soft-tissue expander that adhered to clinical standards. Additionally, the study validated the feasibility of expanding patient-specific silicone expanders within 6 weeks for repairing large left and right mandibular bone defects.

Multi-dimensional parametric study for enhancing Brackish Water Reverse Osmosis membrane performance suited for desalination of low salinity feeds.

Reverse osmosis (RO) effectively provides clean drinking water. Different RO membrane types are tailored to treat saline water feeds with varying characteristics. In the context of low brackish water feeds, the objective is to remove only a minimal excess of salinity through the membrane. Our study introduces a method of membrane post-treatments capable of achieving controlled salt rejection while concurrently enhancing permeate flux, which is vital for achieving effective and energy-efficient desalination of low brackish water. The post-treatments were conducted on our in-house-developed membranes using aqueous solutions of N,N-Dimethylformamide and glycerol for different drying times at the coupon level. The process was scaled up at the module level, allowing us to assess its potential for commercial application. At the coupon level, the permeate flux increased significantly from 3.7 ± 0.9 to 10.6 ± 0.2L/m2·h·bar, while the salt rejection decreased from 95.6 ± 1% to 70.5 ± 1% when measured with a feed of 2,000 ppm NaCl concentration. At the module level, we observed a higher flux of 12.8L/m2·h·bar, alongside a salt rejection of 55.5% with a similar feed. Varying post-treatment parameters at the coupon level allowed us to attain the desired salt rejection and permeate flux values. Physical changes in both pristine and post-treated membranes, including polymer swelling, were observed without chemical alterations, enhancing our understanding of the post-treatment effect and its potential for broader commercial use. PRACTITIONER POINTS: Post-treatment of RO membranes enhances flux. Physical structuring through polymer swelling was observed with the chemical structure unaltered. Post-treatment of RO opens doors for broader energy-efficient desalination application.

Formulation and In Vitro Assessment of Polymeric pH-Responsive Nanogels of Chitosan for Sustained Delivery of Madecassoside.

Madecassoside, a triterpenoid saponin compound mainly isolated from the gotu kola herb (Centella asiatica), shows an extensive range of biological activities, including antiapoptotic, antioxidant, anti-inflammatory, moisturizing, neuroprotective, and wound healing effects. It has been highly used in the management of eczema, skin wounds, and other diseases. Due to poor oral bioavailability, membrane permeability, and intestinal absorption, the clinical application of the madecassoside is limited. Hence, a drug carrier system is needed that not only sustains the release of the madecassoside but also overcomes the drawbacks associated with its administration. Therefore, the authors prepared novel pH-responsive chitosan-based nanogels for the sustained release of madecassoside. Free radical polymerization technique was used for cross-linking of polymer chitosan and monomer methacrylic acid in the presence of cross-linker N',N'-methylene bis(acrylamide). The decrease in polymer crystallinity after polymerization and development of nanogels was demonstrated by XRD and FTIR analysis. The effects of nanogel contents on polymer volume, sol-gel analysis, swelling, drug loading, and release were investigated. Results indicated that high swelling and maximum release of the drug occurred at pH 7.4 compared to pH 1.2 and 4.6, indicating the excellent pH-sensitive nature of the engineered nanogels. High swelling and drug release were perceived with the integration of a high quantity of chitosan, while a decline was observed with the high integration of N',N'-methylene bis(acrylamide) and methacrylic acid contents. The same effects of nanogel contents were shown for drug loading too. Sol fraction was reduced, while gel fraction was enhanced by increasing the chitosan load, N',N'-methylene bis(acrylamide), and methacrylic acid. The Korsmeyer-Peppas model of kinetics was trailed by all nanogel formulations with non-Fickian diffusion. The results demonstrated that prepared nanogels can be employed for sustained release of the madecassoside.

Computer vision-based measurement of pure- and mixed-gas swelling in polymer membranes: Individual and synergistic effects of configurational free volume and thermal rearrangement

Although polymer swelling (i.e., dilation) data are crucial to assess the long-term stability of polymer membranes and correct sorption isotherms for highly sorbing penetrants, the swelling propensity of new generation membranes exhibiting configurational free volume (i.e, triptycene units) has never been investigated. To fill this gap, in this paper we study pure and mixed-gas swelling of a series of thermally rearranged polybenzoxazoles (TPBOs) and their poly(o-hydroxyimide) precursors exhibiting systematically varied amount of configurational free volume. The individual and synergistic effects of configurational free volume and thermal rearrangement on the polymer swelling propensity are presented and discussed. To do so, we use a newly developed experimental approach based on computer vision, which is capable of correcting most of the limitations of traditional methods used to measure swelling and achieve superior accuracy. We show that thermally rearranged glassy polymers exhibiting configurational free volume exhibit better swelling resistance relative to conventional polymers. The fundamental origin of this behavior resides, as explained by the dual mode theory, on the fact that the Langmuir's mode swelling propensity in thermally rearranged triptycene-based polymers is much lower than in glassy polymers exhibiting only conformational free volume. Differences between pure-gas and mixed-gas induced swelling are also highlighted and discussed. Finally, a thorough investigation of the swelling measurement uncertainty and precision is provided and discussed, including an analysis of the major factors affecting experimental uncertainty.

Magnetic resonance insights into the heterogeneous, fractal-like kinetics of chemically recyclable polymers.

Moving toward a circular plastics economy is a vital aspect of global resource management. Chemical recycling of plastics ensures that high-value monomers can be recovered from depolymerized plastic waste, thus enabling circular manufacturing. However, to increase chemical recycling throughput in materials recovery facilities, the present understanding of polymer transport, diffusion, swelling, and heterogeneous deconstruction kinetics must be systematized to allow industrial-scale process design, spanning molecular to macroscopic regimes. To develop a framework for designing depolymerization processes, we examined acidolysis of circular polydiketoenamine elastomers. We used magnetic resonance to monitor spatially resolved observables in situ and then evaluated these data with a fractal method that treats nonlinear depolymerization kinetics. This approach delineated the roles played by network architecture and reaction medium on depolymerization outcomes, yielding parameters that facilitate comparisons between bulk processes. These streamlined methods to investigate polymer hydrolysis kinetics portend a general strategy for implementing chemical recycling on an industrial scale.

Graphdiyne marries PEDOT:PSS to form high-stable heterostructure from 2-unstable components toward ultra-low detection limit of uric acid detection in sweat.

PSS has been used as abiomimetic uric acid (UA) sensor but suffers from unfortunate low detection limit (LOD), narrow detection range and poor stability. Herein, we get graphdiyne (GDY) marry PEDOT:PSS to create a very stable GDY@PEDOT:PSS heterostructure for a biomimetic UA sensor, which accomplishes the lowest LOD (6nM), the widest detection range (0.03μM-7mM) and the longest stability (98.1% for 35days) among the related UA sensors. The sensor was successfully used to in situ real-time detection of UA in sweat. The enhancement mechanisms of the sensor were investigated, and results discover that C≡C of GDY and C = C of PEDOT:PSS can cross-link each other by π-π interactions, making not only the former strongly resistant against oxidation deterioration, but also causes the latterto efficiently prevent water swelling of polymer for poor conductivity, thereby leading to high stability from both components. While the stabilized heterostructure can also offer more active sites by enhanced absorption of UA via π-π interactions for highly sensitive detection of UA. This work holds great promise for a practical sweat UA sensor while providing scientific insight to design a stable and electrocatalytically active structure from two unstable components.

Leveraging Swelling Polymer Nanoparticle Reversibility for Cargo Loading

Leveraging Swelling Polymer Nanoparticle Reversibility for Cargo Loading