Polymer Spheres Research Articles

Synthesis and Characterization of Sodium Alginate Spheres Functionalized with Dicarboxylic Acids for Copper Removal in Aqueous Media

AbstractNew polymeric spheres of sodium alginate (AlgNa) containing dicarboxylic acids—maleic acid (MA) and oxalic acid (OA)—were developed for adsorption of copper metal from water. Water adsorption capacity, elementary composition, structural, morphological, vibrational, and thermal properties were characterized by scanning electron microscopy (SEM), intumescence degree (IG), X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR) spectroscopy, and differential scanning calorimetry. SEM data revealed that functionalization with dicarboxylic acids affects the morphology and surface of the AlgNa matrix. Sample containing MA (0.35 ± 0.004 g) absorbs more water than the OA sphere (0.28 ± 0.007 g). XRD patterns showed that the AlgNa–MA and AlgNa samples exhibit an amorphous nature, whereas the AlgNa–OA sample has a partially crystalline phase. Adsorption experiments were conducted to analyze whether the synthesized spheres could be optimized to reach the best performance in copper adsorption. The adsorbents were most efficient at the highest dosage used (250 mg), corresponding to removal percentages of 84.54 ± 3.97% (AlgNa), 94.21 ± 3.04% (AlgNa–MA), and 84.22 ± 3.39% (AlgNa–OA). The energy‐dispersive X‐ray spectroscopy maps validated the incorporation of Cu2+ ions on the surface of the adsorbents. Kinetic and isotherm assays confirmed the highest efficiency of AlgNa–MA spheres.

Structural Effects on Compressive Strength Enhancement of Cellular Concrete During the Split Hopkinson Pressure Bar Test

In recent years, a kind of novel cellular concrete, fabricated by spherical saturated superabsorbent polymers, was developed. Its compressive behavior under high strain rate loadings has been studied by split Hopkinson pressure bar equipment in previous research, which revealed an obvious strain rate effect. It has been found by many researchers that the dynamic increase factor (DIF) of compressive strength for concrete-like materials measured by SHPB includes considerable structural effects, which cannot be considered as a genuine strain rate effect. Based on the extended Drucker–Prager model in Abaqus, this paper uses numerical SHPB tests to investigate structural effects in dynamic compression for this novel cellular concrete. It is found that the increment in compressive strength caused by lateral inertia confinement decreases from 5.9 MPa for a specimen with a porosity of 10% to 2 MPa for a specimen with a porosity of 40% at a strain rate level of 70/s, while the same decreasing trend was found at other strain rate levels of 100/s and 140/s. The lateral inertia confinement effect inside the cellular concrete specimen can be divided into the elastic development stage and plastic development stage, bounded by the moment dynamic stress equilibrium is achieved. The results obtained in this research can help to obtain a better understanding of the enhancement mechanism of the compressive strength of cellular concrete.

A Win–Win Strategy to Fabricate Multifunctional Doping Materials from Cationic Dyes and Negatively Charged Biomass (Cellulose Nanocrystals)

AbstractIf optical probes with different sensitivity could be performed simultaneously in their hard states (e.g., film), soft states (e.g., gel), and solution states, their sensing accuracy could be enhanced due to the highly mutual calibration. The biomass of cellulose nanocrystals is less compatible with commonly used organo‐fluorescent dyes and require chemical modification to improve their application performance, but this leads to the less‐effective material cost. In this work, depending on the electrostatic attractions between the negatively charged polymer matrix with cationic dyes, the cellulose nanocrystals (CNCs)‐based emissive membranes were prepared by vacuum filtration method. Then, the resulting materials were transformed into hydrogels, or dispersed into water solutions, or further absorbed into commercially available polymer spheres and filter papers, resulting in the optical devices with different states. It is worth mentioning that this preparation process does not require chemical modification of cellulose nanocrystals or the addition of organic dispersants, thus greatly reducing the material cost. Finally, the sensing behaviors toward several important stimuli, such as temperature, pollutants like Cr (VI) and pH changes, were successfully carried out. Overall, our research works highlighted a processable way to fabricate fluorescent, water‐dispersible, portable, long‐time‐storable, cost‐effective sensors to meet versatile application requirements.

Mechanical Properties of Concrete Mixes with Selectively Crushed Wind Turbine Blade: Comparison with Raw-Crushing.

The glass fiber-reinforced polymer (GFRP) materials of wind turbine blades can be recovered and recycled by crushing, thereby solving one of the most perplexing problems facing the wind energy sector. This process yields selectively crushed wind turbine blade (SCWTB), a novel waste that is almost exclusively composed of GFRP composite fibers that can be revalued in terms of their use as a raw material in concrete production. In this research, the fresh and mechanical performance of concrete made with 1.5%, 3.0%, 4.5%, and 6.0% SCWTB is studied. Once incorporated into concrete mixes, SCWTB waste slightly reduced slumps due to the large specific surface area of the fibers, and the stitching effect of the fibers on mechanical behavior was generally adequate, as scanning electron microscopy demonstrated good fiber adhesion within the cementitious matrix. Thus, despite the increase in the content of water and plasticizers when adding this waste to preserve workability, the compressive strength only decreased in the long term with the addition of 6.0% SCWTB, a value of 45 MPa always being reached at 28 days; Poisson's coefficient remained constant from 3.0% SCWTB; splitting tensile strength was maintained at around 4.7 MPa up to additions of 3.0% SCWTB; and the flexural strength of mixes containing 6.0% and 1.5% SCWTB was statistically equal, with a value near 6.1 MPa. Furthermore, all mechanical properties of the concrete except for flexural strength were improved with additions of SCWTB compared to raw crushed wind turbine blade, which apart from GFRP composite fibers contains approximately spherical polymer and balsa wood particles. Flexural strength was conditioned by the proportion of fibers, their dimensions, and their strength, which were almost identical for both waste types. SCWTB would be preferable for applications in which compression stresses predominate.

Mercury Adsorption by Ca-Based Shell-Type Polymers Synthesized by Self-Assembly Mineralization.

Adsorption is one of the most promising strategies for heavy metal removal. For Hg(II) removal, mineralized Ca-based shell-type self-assembly beads (MCABs) using alginate as organic polymer template were synthesized in this work. The adsorbent preparation consists of gelation of a Ca-based spherical polymer template (CAB) and rate-controlled self-assembly mineralization in bicarbonate solution with various concentrations. The comparative study demonstrates that 1% (MCAB-1) is the optimal concentration of bicarbonate. Based on this condition, the maximum adsorption capacity (48 ± 4 mg/g) of MCAB-1 was observed at pH = 5 in a batch test, which was 2.67 times more than that of the unmodified one, CAB, at 18 ± 1 mg/g. Long-duration (10 h) adsorption tests showed that MCAB-1 exhibited remarkable performance stability and anti-wear ability (43.2% removal efficiency and 74.3% mass retention, compared to 2.7% and 38.6% for CAB at pH = 3, respectively). The morphology determination showed that a shell-type porous amorphous carbonate layer was formed at the surface of the organic polymer template by rate-controlled self-assembly mineralization. This transition not only promotes the pore structure and activated cation binding functional sites, but also improves the anti-wear ability of materials effectively.

Morphology-controlled mesoporous core–shell carbon nanospheres decorated with Cu nanoparticles as highly efficient and reusable catalyst

Environmental pollution caused by industrial waste has recently become a serious issue. Therefore, effective pollutant removal using nanotechnology is required, in which catalysts based on precious metals, such as Pt, Ag, Au, and Pd, are widely utilized. However, the manufacturing costs of precious metal catalysts are high. In this study, copper, a promising metal for catalysis, is evaluated as an alternative to precious metal catalysts because of its low cost, high efficiency, and abundant natural reserves. However, nanoparticle agglomeration is problematic when evaluating the catalytic performance of isolated metal nanoparticles. To solve this problem and maintain a high catalytic activity of Cu, in this study, Cu was loaded on a mesoporous carbon support derived from a carbon precursor with a core–shell structure. The core–shell-structured carbon precursor was obtained by coating resorcinol-formaldehyde polymer spheres as the core with a 50 nm thick polydopamine shell with 10 nm mesopores through π–π stacking interactions. A copper precursor was used to form Cu(OH)2 on the surface of the support, and then the nanocomposite was synthesized at 500 °C for 2 h. The synthesized copper-carbon nanocomposite exhibits high catalytic activity owing to its high specific surface area, porosity, and accessible internal space. It exhibits excellent catalytic activity and stability, along with excellent reusability, in the reduction of 4-nitrophenol to 4-aminophenol using NaBH4. Moreover, excellent catalytic activity, exceeding 99 %, was achieved in the reduction of another organic dye, methylene blue.

Efficient synthesis of narrow or monodisperse, physically cross-linked, and “living” spherical polymer particles via one-stage ambient temperature photoiniferter-RAFT precipitation polymerization and its particle formation mechanism

Efficient synthesis of narrow or monodisperse, physically cross-linked, and “living” spherical polymer particles via one-stage ambient temperature photoiniferter-RAFT precipitation polymerization and its particle formation mechanism

Catalytic degradation of nitrobenzene derivatives by platinum nanoparticles stabilized in diblock spherical polymer brushes

Abstract A new type of core–shell diblock spherical polymer brushes, poly 2-(methacryloyloxy)ethyl-trimethylammonium chloride-b-poly(N-isopropylacrylamide) diblock polymer brushes with polystyrene cores (PSV@PMETAC-b-PNIPA), was prepared through a surface-initiated photoiniferter-mediated polymerization method. The PSV@PMETAC-b-PNIPA (DSPB) was further used as the nanoreactor to prepare and stabilize platinum nanoparticles in situ (DSPB@Pt). By controlling the reaction temperature, substances with similar structure but different hydrophilicity, i.e. 4-nitrophenol and nitrobenzene, could be catalyzed by DSPB@Pt with different catalytic behaviors.

Highly Interconnected Macroporous Carbon Spheres for Ionogel-Based Stretchable Supercapacitors

Due to their exceptional properties such as lightweight, high electrical conductivity, specific surface area (SSA), adjustable pore structures, and desired surface characteristics, carbonaceous materials have substantial interest as electrode materials for supercapacitors (SCs). In attempts to achieve high energy density, ionic liquid (IL) electrolyte is has attracted great attention Because it can be used in a wide voltage range. However, initial attempts to incorporate IL into SCs encountered challenges, as the large and sluggish ions struggled to effectively access the narrow pores of conventional microporous carbons. In addressing these issues, we have synthesized interconnected meso/macroporous carbon spheres (MCSs) that were produced via co-assembly of polymer and silica sphere (20-70 nm). The interconnected large meso/macropores facilitated ion mass-transport and thereby efficient utilization of the carbon electrode's surface for capacitive energy storage. The MCS-based SCs demonstrated a high capacitance (328.93 F g-1) and ultrahigh energy density (182.7 Wh kg-1), and MCS/IL-based inogel SCs exhibited a remarkably high energy density of 0.111 mWh cm⁻ 2 and a high-power density 8.89 m Wcm-2 demonstrated excellent mechanical durability 0% and 100% strain, with notable capacitive retention of 95.3% observed at 100% strain. Comparable to the best results reported to date. Therefore, the results obtained in this study provide morphological insights into the differences in electrochemical performance based on pore size and particle size. Additionally, these findings contribute to the design of carbon-based materials suitable for electrochemically robust yet dynamically sluggish ionic liquid electrolytes, aiming for high-performance deformable energy supply devices.

Controllable fabrication of monodisperse Fe-doped polystyrene spheres using microfluidic technology

Doped polymer spheres are essential for preparing targets for the inertial confined fusion (ICF) experiments since they can provide important information about the implosion. To prepare Fe-doped polystyrene (PS) spheres, ferrocene-doped PS spheres were successfully prepared by a straightforward method combining physical doping and microfluidic technology. The effect of ferrocene on the quality of the PS spheres was investigated and the relevant mechanism was discussed. Due to the compatibility of PS, ferrocene and fluorobenzene, the Fe-doped polystyrene spheres exhibited good monodispersity, sphericity and surface finish when the ferrocene content in the oil phase solution was lower than 3 %. These properties can meet stringent design requirements for ICF. This study provides valuable insights for the preparation of doped polymer spheres for ICF experiments.

Compliant Interconnects Based on Single Micrometer-sized Metal-Coated Polymer Spheres.

The rapid evolution of multifunctional electronics necessitates interconnection technologies appropriate for large dies with high-density and/or ultrafine pitch input/output pins. Existing technologies face numerous challenges, including demands for bonding equipment that can deliver extremely high force as well as thermo-mechanical stresses induced in the assembled packages due to mismatched thermal expansion of materials involved. This study proposes an approach to compliant interconnects comprising single micrometer-sized metal-coated polymer spheres, being joined to mating electrodes by sintering of Ag nano ink at low temperature (140 °C) and low pressure (∼15 mN/particle). Such an interconnection technology is expected to enhance the thermo-mechanical robustness of the assembled packages as well as be capable of high-density, ultrafine pitch interconnects. Our approach demonstrates control over conductive particles during assembly, achieving a 98% success rate in individual interconnects with a single captured particle. The use of sintered Ag not only secures free-standing particles on electrical pads (with an adhesion force above 2 μN) but also results in a 15% reduction in interconnect resistance, with measured resistance as low as 0.5 Ω, compared to interconnects without Ag ink. This method presents an alternative to metallurgical joints, particularly suited for high-density, ultrafine pitch applications, offering low bonding pressure and temperature, along with improved interconnect compliance to enhance the thermo-mechanical robustness of the packages.

Alkyne-rich patchy polymer colloids prepared by surfactant-free emulsion polymerization

While free radical polymerization methods are employed frequently to prepare sub-micron polymer particles, we hypothesized that surfactant-free emulsion polymerization (SFEP)11Surfactant-free emulsion polymerization methodology may prove beneficial for obtaining functional polymer particles by solution polymerization methods that preclude the need for conventional surfactants. To test the effectiveness of SFEP for the preparation of functional colloids, solution polymerization of several monomers, including propargyl acrylate (PA),22Propargyl acrylate. styrene (Sty)33Styrene. and tert-butyl acrylate (t-BA),44Tert-butyl acrylate. was performed over a range of monomer ratios and reaction scales. Electron microscopy and infrared spectroscopy were employed to evaluate the outcome of SFEP for particle size, shape, surface anisotropy, and chemical composition. Combining this characterization with optimized SFEP synthesis, we found that spherical polymer particles—homopolymers of PA as well as copolymers—were obtained in the 60–300 nm diameter size range. Successful inclusion of PA enabled the use of the particles in copper-catalyzed azide-alkyne cycloaddition reactions (CuAAc).55Copper-catalyzed azide-alkyne cycloaddition Moreover, electron microscopy characterization with backscattering revealed chemical and shape anisotropies on copolymer particles indicative of monomer phase-separation during particle formation. Overall, the SFEP methodology represents a straightforward, one-pot, bottom-up approach to yield a library of functional polymer particles, while avoiding undesirable aspects associated with conventional surfactants.

Alkaline ILs Supported onto Mesoporous Polymeric 3D Spheres for Catalytic Synthesizing Dimethyl Carbonate in Transesterification

AbstractA novel type of alkyl amine‐based ILs [Et3N]+[OH]− (triethylammonium hydroxide) behaving strong alkali property have been chemically immobilized onto the polymeric 3D spheres with mesoporous structures, spherical morphology and more uniformed active species onto them to form alkali ILs supported 3D polymeric catalysts(3DPs‐ILsOH), which was synthesized via a combined method of substitution with its subsequent anion unites’ exchanging process. The supported 3DPs‐ILsOH catalyzed the transesterification of ethylene carbonate (EC) with methanol, which preferred to exhibit the excellent, efficient activities. At milder reaction temperature of 70 °C within 4.0 h, the conversion of EC achieved to 83.3 % with 99.5 % selectivity of dimethyl carbonate (DMC). Under the same reaction conditions, this type of catalysts could be recovered by a simple filtration and was reused eight times without obvious losing catalytic activities and hardly without any leaching of catalytic species. Its’ catalytic process for generating the chemical of DMC from the CO2 fixation material of EC was studied by using the in‐situ FTIR, and was further verified that the synergetic function roles of triethyl amino cations units with OH− anion units onto the supported catalysts might be one of the important reasons for progressing DMC's yields and its’ catalytic efficiency in transesterification reaction.

Microfluidics-Driven Dripping Technique for Fabricating Polymer Microspheres Doped with AgInS2/ZnS Quantum Dots.

Fluorescent microspheres are at the forefront of biosensing technologies. They can be used for a wide range of biomedical applications. They consist of organic dyes and polymers, which are relatively immune to photobleaching and other environmental factors. However, recently developed AgInS2/ZnS quantum dots are a water-soluble, low-toxicity class of semiconductor nanocrystals with enhanced stability as fluorescent materials. Here, we propose a simple way for making microspheres: a microfluidic dripping technique for acrylamide polymer spheres doped with quantum dots. Analyses of their spectra show that the emission of quantum dots, dispersed in water, is saturated with an increasing pump intensity, while quantum dots embedded into polymer microspheres exhibit a more sustained emission. Moreover, our study unveils a remarkable reduction in the luminescence lifetime of quantum dots embedded in microspheres: the mean value of the decay time for quantum dots in solutions was 91 and 3.5 ns for similar quantum dots incorporated into polymer microspheres.

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.

Sonochemical deposition of gold nano-shells on suspended polymeric spheres

Metal nanoparticles have drawn great interest due to their unique properties for applications in the fields of catalysis, biomedicine and environmental science depending on the architecture of the metal nanoparticle composites. Amongst different designing routes, the chemical template deposition offers great flexibility in terms of the template selection and interfacial interactions, giving rise to controllable designs. In order to control over nanoparticle size distribution and deposition efficiency, a sonochemical approach has been systematically followed in this study. Key parameters of the ultrasound-assisted deposition procedures during the seeding step to synthesise gold nanoparticle-coated poly(styrene) beads were investigated. The impact of the solution pH and the ultrasonic frequency on the template deposition was examined at 139, 300, 500 and 1000 kHz. The results, monitored by transmission electron spectroscopic imaging, show that the highest gold deposition was achieved at 300 kHz, revealing the mechanistic details of the nucleation-crystal growth behaviour as a function of ultrasonic frequency and reaction time. In addition, the concentration ratio between gold ions and poly(styrene) beads was varied. The highest deposition coverage and smallest particle size were reached at 0.05 mM and 2.5 mg, respectively. The proposed mechanism of the MNPs formation and deposition behaviour were then discussed based on the tested parameters.

From Cauliflowers to Microspheres: Particle Growth Mechanism in Self-Stabilized Precipitation Polymerization.

Self-stabilized precipitation (2SP) polymerization enables the facile synthesis of uniform polymer spheres with sizes ranging from 100 nm to 3 μm, without the need for stabilizers or cross-linkers, even at high monomer concentrations of up to 30%. While previous studies have extensively explored the influence of reaction conditions on the size and uniformity of microsphere products, their impact on particle morphology has received less attention. In this work, we demonstrate that particle growth in 2SP polymerization primarily occurs via the adsorption of polymers from the solution onto the particle surface, leading to an increase in particle circularity and a smoother surface. The surface roughness of the particles is controlled by the aggregation of primary particles and the subsequent polymer adsorption process during the growth stage. Smooth microspheres are obtained under conditions of moderate monomer concentration, high initiator concentration, and elevated temperature. Our findings highlight the significance of the particle growth process in determining particle morphology in addition to the well-established role of polymer-solvent interactions during precipitation polymerization.

Preparation of porous lead zirconate titanate piezoelectric ceramics via vat photopolymerization combined with burnt polymer spheres technique

Porosity plays an important factor on the electric properties of piezoelectric ceramics. Here, we propose a promising method for the fabrication of Lead zirconate titanate (PZT) piezoelectric ceramics using vat photopolymerization, and effectively modulate porosity of printed PZT piezoceramics through adjusting the polystyrene (PS) content. After a post-process, the PZT piezoelectric ceramics showed single perovskite structure and porous microstructures formed by PS, with porosity ranging from 8.57 % to 27.02 %. With the increase of porosity, the piezoelectric strain constant (d33) and dielectric permittivity (ɛr) decreased gradually due to the reduction in the volume fraction of PZT phase per unit volume. When the PS content was 20 vol%, d33 and ɛr reached the maximum values. The sintered PZT piezoelectric ceramics exhibited excellent electrical properties (ɛr=2364, d33=399 pC/N, g33=1.91×10−2 Vm/N, d33g33=7.62×10−12 m2/N and Kt=43.94 %). This work not only provides technical support for manufacturing advanced ceramics with tunable porosity through the use of PS powders, but also lays the foundation for preparing functional ceramics with complicated designed structures through vat photopolymerization technology.

Collimated beam formation in 3D acoustic sonic crystals

We demonstrate strongly collimated beam formation, at audible frequencies, in a three-dimensional acoustic phononic crystal where the wavelength is commensurate with the crystal elements; the crystal is a seemingly simple rectangular cuboid constructed from closely-spaced spheres, and yet demonstrates rich wave phenomena acting as a canonical three-dimensional metamaterial. We employ theory, numerical simulation and experiments to design and interpret this collimated beam phenomenon and use a crystal consisting of a finite rectangular cuboid array of 4×10×10 polymer spheres 1.38 cm in diameter in air, arranged in a primitive cubic cell with the centre-to-centre spacing of the spheres, i.e. the pitch, as 1.5 cm. Collimation effects are observed in the time domain for chirps with central frequencies at 14.2 kHz and 18 kHz, and we deployed a laser feedback interferometer or Self-Mixing Interferometer – a recently proposed technique to observe complex acoustic fields—that enables experimental visualisation of the pressure field both within the crystal and outside of the crystal. Numerical exploration using a higher-order multi-scale finite element method designed for the rapid and detailed simulation of 3D wave physics further confirms these collimation effects and cross-validates with the experiments. Interpretation follows using High Frequency Homogenization and Bloch analysis whereby the different origin of the collimation at these two frequencies is revealed by markedly different isofrequency surfaces of the sonic crystal.

The Paradoxical Behavior of Rough Colloids at Fluid Interfaces.

Colloidal particles adsorb and remain trapped at immiscible fluid interfaces due to strong interfacial adsorption energy with a contact angle defined by the chemistry of the particle and fluid phases. An undulated contact line may appear due to either particle surface roughness or shape anisotropy, which results in a quadrupolar interfacial deformation and strong long-range capillary interaction between neighboring particles. While each effect has been observed separately, here we report the paradoxical impact of surface roughness on spherical and anisotropic ellipsoidal polymer colloids. Using a seeded emulsion polymerization technique, we synthesize spherical and ellipsoidal particles with controlled roughness magnitudes and topography (convex/concave). Via in situ measurement of the interfacial deformation around colloids at an air-water interface, we find that while surface roughness strengthens the quadrupolar deformation in spheres as expected by theory, in stark contrast, it weakens the same in ellipsoids. As roughness increases, particles of both shapes become more hydrophilic, and their apparent contact angle decreases. Using numerical predictions, we show that this partially explains the decreased interfacial deformation and capillary interactions between the ellipsoids. Therefore, particle surface engineering has the potential to decrease the capillary deformation by asymmetric particles via changing their capillary pinning, as well as wetting behavior at fluid interfaces.