Polymer Particles Research Articles

Self-Healing and Mechanical Behaviour of Fibre-Reinforced Ultra-High-Performance Concrete Incorporating Superabsorbent Polymer Under Repeated and Sustained Loadings

This study investigated the mechanical responses and self-healing capability of incorporating superabsorbent polymer (SAP) particles in Fibre-Reinforced Ultra-High-Performance Concrete (UHPC) mixes under repetitive flexural and sustained tensile loadings. UHPC with SAP addition of 0.3% and 0.4% of the binder ratio were studied along with a control UHPC mix. The methodology included investigating the mechanical properties of these mixes under ambient, water, and 100% of relative humidity (RH) curing conditions. In addition, the mechanical performance of ambient-, water-, and 100% RH-cured prismatic specimens (100 mm × 100 mm × 500 mm) under repeated load was studied under the same curing conditions. Prismatic specimens (75 mm × 75 mm × 500 mm) were kept under cure conditions of wet and dry cycles with applied tensile load for 28 days for the sustained tensile load. The results showed that incorporating SAP into UHPC enhances the elastic modulus, flexural strength, and tensile strength. Also, mixes with SAP have exhibited compressive strength above 120 MPa after 90 days. Furthermore, the load recovery of the prisms under repetitive flexural load and prisms under sustained tensile loading demonstrated the self-healing efficiency of SAP incorporated into the UHPC mixes higher than the control mix specimens.

Hydrophobic ion pairing as a novel approach to co-axial electrospraying of peptide-PLGA particles

Electrospraying is a processing technique that has gained much interest to prepare polymeric particles. The technique operates at ambient temperature, thereby avoiding heat induced degradation of labile therapeutics (e.g. peptides and proteins). Exposure to organic solvents can be minimised by co-axial electrospraying through separation of core (aqueous) and shell (organic) solvents. However, aqueous solutions are often difficult to electrospray due to high surface tension. Immiscibility between the core–shell solvents creates a further process challenge. Herein, we describe for the first time the use of hydrophobic ion pairing (HIP) to encapsulate a polypeptide into polymeric particles prepared by co-axial electrospraying. Peptide ion pairs were prepared to incorporate a model peptide – teriparatide – into an organic solvent, permitting facile electrospraying while also protecting the peptide from denaturation. Teriparatide loaded PLGA particles were generated by electrospraying from aqueous or ethanolic peptide solutions (core). A PLGA solution in chloroform (with and without co-solvents) was employed as the shell solution. The aqueous core solution led to a teriparatide encapsulation efficiency of 79.2 ± 19.8 %, which was not significantly different from the ethanolic core (57.1 ± 14.5 %). When aqueous solutions were used the process lacked reproducibility, resulting in low process yields (61.3 ± 4.0 %). In contrast, when an organic core was used a dry powder bed was achieved with a yield of 102.2 ± 8.8 %. The peptide’s integrity and biological functionality were retained after electrospraying as ion pairs, as evidenced in a cell-based PTH1R receptor binding assay.

Multifunctional superhydrophobic coating constructed from rosin-based polymer and nano-boehmite particles for oil-water separation, flame retardancy and anti-icing

The massive release of oily wastewater poses a significant threat to ecological systems and environ mental sustainability. Superhydrophobic materials have been regarded as an effective solution for the treatment of oily wastewater. Herein, a multifunctional superhydrophobic coating (poly(DR-DMA)@BMP coating) was developed using a constructed from rosin-based polymer (poly(DR-DMA)) and nano-boehmite particles (BMP). Poly(DR-DMA) was fabricated by double-bond modified dopamine (DMA) and double-bond functionalized rosin acid (DR). The poly(DR-DMA)@BMP coating exhibited excellent superhydrophobicity with a water contact angle of up to 163°, along with self-cleaning performance. Meanwhile, the poly(DR-DMA)@BMP coating had desirable oil-water separation, with a permeation flux of 8966.67 L·m−2·h−1, and an n-heptane separation efficiency of 98.26 %. After 10 separations, the permeation flux and separation efficiency remained high. In addition, the poly(DR-DMA)@BMP coating retained excellent superhydrophobicity (water contact angle >150°) and emulsions separation after mechanical and chemical treatment. Thermo-gravimetric analysis and Derivative thermo-gravimetry curves illustrated increased thermal stability of the coating, which indicated that the poly(DR-DMA)@BMP coating exhibited a certain degree of flame retardancy. The freezing time of water droplets on the coated sample was extended to 1100 s at −20 °C, indicating that the poly(DR-DMA)@BMP coating had favorable anti-icing properties. To encapsulate, the poly(DR-DMA)@BMP coating holds promising applications in the realms of oil-water separation, flame retardancy and anti-icing.

Polymeric Adsorbent for the Effective Removal of Toxic Dyes from Aqueous Solutions: Equilibrium, Kinetic, and Thermodynamic Modeling

AbstractThis study investigates the adsorption behavior of anionic (Congo red, Eosin yellow) and cationic (Malachite green) dyes on synthesized TD polymer particles, highlighting the material's potential as an effective adsorbent for industrial wastewater treatment. Key operational parameters, including initial solution's pH, contact time, initial dye concentration, and temperature, were systematically evaluated to determine their influence on adsorption efficiency. The experimental data demonstrated that the Langmuir isotherm provided the best fit for all three dyes, indicating monolayer adsorption with maximum adsorption capacities of 153.8 mg/g for Malachite green, 49.36 mg/g for Congo red, and 227.9 mg/g for Eosin yellow. Kinetic analysis revealed that the adsorption of Malachite green and Congo red followed pseudo‐second‐order kinetics, while Eosin yellow adsorption was better described by the intra‐particle diffusion model. Thermodynamic assessments, including Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°), confirmed the spontaneous and endothermic nature of the adsorption processes for Malachite green and Eosin yellow, contrasting with the exothermic behavior observed for Congo red. These findings underscore the versatility and effectiveness of TD polymer particles in removing both anionic and cationic dyes from aqueous solutions. Further research could explore material optimization and real‐world applications to broaden their utility in sustainable water treatment strategies.

Microplastics Pollution in Tropical Estuary (Muttukadu Backwater), Southeast Coast of India: Occurrence, Distribution Characteristics, Potential Sources and Ecological Risk Assessment

Around the world, microplastic pollution is pervasive and is regarded as the biggest threat to all ecosystems. We conducted the present study to determine the prevalence of microplastics (MPs), their polymer hazard risk (PHI), and any potential sources of these particles in the estuary of Muttukadu Backwater, Southeast Coast of India. Microplastics were extricated from surface water and sediment by the wet peroxide method, identified by a stereo zoom microscope (SM), and characterized by ATR-FTIR and SEM-EDS analysis. The average microplastic abundance in sediment and surface water was 815±158 particles Kg−1 and 195±38 particles m−3, respectively. The most common microplastics based on shapes were fibers and fragments in both sediment and surface water, with blue and green-colored microplastics being the most frequently observed colors. Type II polymer particles (<3.00 mm–1.00 mm) are dominant particles in sediment (36%), and type I (5.00 mm–3.00 mm) particles dominate in surface water samples (49%). Energy dispersive X-ray spectrometer (EDS) results showed that the following chemical elements, such as O, C, Cl, Fe, Na, Al, K, Ca, and Si, as well as the order of the trace metal Pb > Cr > Ni > Co > As > Cu > Cd > Zn, are observed by microplastics of all sediment sampling location. The pollution load index (PI), polymer hazard index (PHI), and potential ecological risk (PER) index models revealed varying level of risk. The polymer hazard index (PHI) reveals that both water and sediments are moderate to highly MP contamination. The hazards of polymers such as polyethylene, polystyrene, polyester, and polyamide significantly contributed to hazard level IV. Inadequate plastic waste management, human habitation and tourism, rapid industrialization, and coastal construction are the main sources of microplastic contamination in the study area. The proper guidelines, potential policies, and technological interventions are much needed to reduce the microplastic contamination along Southeast Coast of India.

Dual drug delivery systems based on natural and synthetic polymer particles for isoniazid and rifampicin vehiculization

AbstractThe purpose of this work is the design and characterization of novel systems based on micro and nanoparticles prepared from poly(lactic‐co‐glycolic) acid (PLGA), chitosan (CHT) and gelatin (GEL) for compartmentalization and dual release of rifampicin and isoniazid. The emulsion/evaporation method is employed for the preparation of PLGA based microparticles and nanoparticles. CHT and GEL are used for the preparation of microparticles by spray‐drying. Entrapment efficiencies are in the range of 35%–73% and 5%–29% for rifampicin and isoniazid in PLGA microparticles, respectively. For isoniazid GEL:CHT particles the entrapment efficiencies are within 82%–100%. Isoniazid shows a complete release at acid condition from GEL:CHT particles, while rifampicin release is maintained from GEL:CHT particles or displays an slightly increase from PLGA particles during buffer conditions. Antimycobacterial activity experiments show that the formulations present the ability to inhibit the bacterial growth in comparison with a control culture without treatment. Rifampicin PLGA and isoniazid GEL:CHT microparticles could be used for the preparation of a dual drug delivery system with each antibiotic in a single particulate compartment. GEL:CHT microparticles containing free isoniazid and rifampicin PLGA nanoparticles are a novel two compartment delivery system.

A Facile Method in Fabricating Flexible Conductive Composites with Large-Size Segregated Structures for Electromagnetic Interference Shielding.

To resist the plastic deformation of polymer particles during hot press molding, high molecular weights, and moduli are required for composites with segregated structures, thus the prepared composites exhibit poor flexibility. Also, larger particle sizes can bring lower percolation thresholds while the ensuing greater deformation destroys the conductive network. Moreover, segregated composites still face preparation complexities. Herein, a facile method for developing flexible composites with large-size segregated structures is proposed. First, silver-coated polydopamine-modified reduced graphene oxide (Ag@PrGO), as conductive fillers, is prepared by electroless plating. Next, polydimethylsiloxane (PDMS)-coated polyolefin elastomer (POE) beads are put into a bag containing the fillers. After a simple shaking, the fillers are adhered to the POE surface as the cohesive property of cured PDMS. Finally, flexible composites with large-size segregated structures are obtained via hot pressing. Benefiting from the 2D structure of the Ag@PrGO and the ability to slip, the conductive networks possess adaptable deformability. The prepared composites exhibit excellent electrical conductivity (203.55 Scm-1) at filler volume fractions of 3.4 vol%. The EMI shielding effectiveness can reach 70dB in the X-band at a thickness of 1.9mm and remains stable after bending and rubbing damage. This work paves the way for constructing large-size segregated structures.

Effect of Rheological on the Physical and Electrical Properties of Extruded Micro Carbon -LLDPE Composites

This study focuses on formulating and optimizing a conductive polymer composite (CPC) material tailored for electromechanical applications. Linear Low-Density Polyethylene (LLDPE) polymer and micro carbon particles derived from rice husk were compounded using a hot compaction process and melt blended through a single-screw extrusion machine. A mix of 50% loading of microcarbon particles was used in this research. It was determined that the experiment was successfully conducted, resulting in a stabilized density of approximately 1 g/cm³. The research demonstrates how the prototype Extruder Head effectively stabilizes the density of composites. Electrical conductivity demonstrated a notable increase in conductivity toward higher density. These findings underscore the successful development of a CPC material with improved electrical conductivity, making it a highly suitable tool for high carbon-loading composite material.

Research Progress on Peptide Drugs for Type 2 Diabetes and the Possibility of Oral Administration

Diabetes is a global disease that can lead to a range of complications. Currently, the treatment of type 2 diabetes focuses on oral hypoglycemic drugs and insulin analogues. Studies have shown that drugs such as oral metformin are useful in the treatment of diabetes but can limit the liver’s ability to release sugar. The development of glucose-lowering peptides has provided new options for the treatment of type 2 diabetes. Peptide drugs have low oral utilization due to their easy degradation, short half-life, and difficulty passing through the intestinal mucosa. Therefore, improving the oral utilization of peptide drugs remains an urgent problem. This paper reviews the research progress of peptide drugs in the treatment of diabetes mellitus and proposes that different types of nano-formulation carriers, such as liposomes, self-emulsifying drug delivery systems, and polymer particles, should be combined with peptide drugs for oral administration to improve their absorption in the gastrointestinal tract.

One-pot fabrication of bio-inspired shape-morphing bilayer structures

Soft bilayer structures capable of shape morphing in response to external stimuli have been commonly adopted in the design of soft robots, flexible electronics and many other smart systems. However, existing methods to fabricate such structures generally require multiple steps and may end up a weak interface between the two layers. Here, we report a one-pot fabrication strategy to generate elastomer-based shape-morphing bilayer structures with a seamless interface. Our strategy leverages on a recently developed bioinspired polymer-NaCl particle composite system which can undergo significant osmotic swelling in water. Bilayer structures are readily formed after the precipitation of NaCl particles in liquid polymers under gravity and the crosslinking of the polymers. The shape-morphing behavior of the fabricated bilayer structures can be well controlled by tuning the particle precipitation kinetics, NaCl content, and crosslinking level of the polymer matrix. More importantly, the bilayer structures fabricated using this strategy exhibit more complex shape-morphing responses than typical bilayer structures. Considering the wide applicability of NaCl particle-induced osmotic swelling of polymer composites, our one-pot bilayer formation strategy will greatly benefit many shape-morphing applications with a simplified fabrication workflow and enhanced configurational versatility.

Poly(butylene succinate) Microparticles Prepared Through Green Suspension Polycondensations

AbstractThe demand for sustainable polymer particles production is growing, driven by the need for efficient, biocompatible, and biodegradable materials. In this context, the present study explores the production of poly(butylene succinate) (PBS) particles in a single step using a green heterogeneous suspension process, using vegetable oil as the suspending medium. Particularly, the effects of oil type (soybean, corn, sunflower), dispersed phase holdup (10–30 wt.%), stabilizers (Span 20, Span 80, Tween 80, Brij 52, Brij 93, Igepal‐co‐520, Polyglycerol polyricinoleate (PGPR)), reaction time (1–5 h), and temperature (100–160 °C) on the suspension polymerization are investigated. Results indicate that particle size and shape are influenced by the vegetable oil and stabilizer. Additionally, it is shown that the particle size distribution is affected by the use of a sonicator, allowing the manufacture of even smaller microsized particles. Based on the results, a 30 wt.% holdup in corn oil with a blend of surfactants can be recommended, producing spherical particles with an average diameter of 100 µm. Moreover, higher reaction temperatures (160 °C) and longer reaction times (5 h) positively impacted the molar mass of the obtained particles. Finally, cytotoxicity tests using Bone Marrow‐Derived Macrophages cells confirmed the safe use of PBS microparticles at concentrations up to 1000 µg mL⁻¹

Microstructure-mechanical property relationships of polymer nanocomposite reinforced with lyophilized montmorillonite/carbon nanotubes hybrid particles

Abstract Introducing multi-walled carbon nanotubes (MWCNT) and montmorillonite (MMT) simultaneously into a polymer can significantly enhance its properties. Meanwhile, choosing the best technique to homogeneously disperse these nanohybrid particles in polymers, without agglomerates, is still a challenge. In this study, a hybrid MMT/MWCNT, prepared by lyophilization process, is introduced in polylactide (PLA). Morphology of the resulting nanocomposites displays synergistic relationships of the MMT/MWCNT, facilitating dispersion in PLA. The analysis of transmission electron microscopy (TEM) specific particle densities of PLA0.5hyb, PLA1.0hyb, and PLA2.0hyb shows values of 77, 64, and 35 µm⁻2, respectively. This suggests that MMT platelets are significantly more exfoliated in PLA0.5hyb compared to the other nanocomposites. It also indicates that filler aggregation increases as the MMT/MWCNT concentration increases. Compared to neat PLA, elastic modulus of nanocomposites increased by up to 46 %, demonstrating the reinforcing effect of MMT/MWCNT hybrid nanofillers. The nanocomposites exhibit viscosity, plasticity and damage phenomena, which are significantly decreased because of the MMT/MWCNT incorporation, compared to neat PLA. Furthermore, the viscoelastic properties, analyzed by dynamic thermal-mechanical analysis, record about 27 % increase in the storage modulus of the nanocomposites compared to PLA, indicating the effectiveness of the hybrid MMT/MWCNT in increasing the resistance of PLA/MMT/MWCNT nanocomposite against thermomechanical aggression.

Nonuniversal Dynamics of Hyperbranched Metallo-Supramolecular Polymer Networks by the Spontaneous Formation of Nanoparticles.

Various transient and permanent bonds are commonly combined in increasingly complex hierarchical structures to achieve biomimetic functions, along with high mechanical properties. However, there is a traditional trade-off between mechanical strength and biological functions like self-healing. To fill this gap, we develop a metallo-supramolecular polymer hydrogel based on the hyperbranched poly(ethylene imine) (PEI) backbone and phenanthroline ligands, which have unexpectedly high plateau modulus at low concentrations. Rheological measurements demonstrate nonuniversal metal-ion-specific dynamics, with significantly larger plateau moduli, longer relaxation times, and stronger temperature dependencies, compared to equivalent networks based on model-type telechelic precursors, which cannot be explained by the theory of linear viscoelasticity. TEM images reveal the in situ mineralization of metal ions, which nucleate by the ligand complexation and grow thanks to the spontaneous reducing effect of the PEI backbone. Evidently, the complex lifetime works against Ostwald ripening, resulting in the formation of thermodynamically stable smaller particles. This trend is followed by time-dependent network buildup measurements and is confirmed by a kinetic model for particle formation and aggregation. The spontaneous formation of particles with complex lifetime-dependent sizes can explain the nonuniversal dynamics through the interaction of polymer segments and particles at the nanoscale. This work describes how the polymer backbone can affect the strength and stability of supramolecular bonds, promising for combining high mechanical properties and self-healing comparable to natural tissues.

Development and performance evaluation of hydrophobic association plugging agents for sealing formation prior to cementing

This study introduces a novel blocking agent composed of polymerized hydrophobic particles to address the challenge of sealing formations with heterogeneous permeability. These particles display high viscosity and adsorption capabilities, essential for sealing highly permeable formations effectively. Hydrophobic associative polymers (AMSN) were prepared using free radical micellar polymerization, grounded in hydrophobic association principles and molecular design. Optimal monomer ratios and synthesis procedures were identified through the observation of the polymers’ apparent viscosity in aqueous solutions. Characterization of the polymers involved Fourier transform infrared spectroscopy, thermogravimetric analysis, and fluorescence analysis to assess their temperature and salt resistance, reduction in filtrate loss, and blocking abilities. The polymers, containing hydrophobic groups at 300 mg/L concentrations, demonstrated excellent temperature resistance, maintaining 50% of their original viscosity at 95 °C, and sustained effectiveness in 50 g/L salt solutions, surpassing conventional polymers like HPAM. The sealing effect of this hydrophobic conjugated polymer on cracks with different openings can effectively solve the leakage problem. It addresses the need for effective plugging in heterogeneous formation with uncertain leak channel dimensions. Therefore, this study is of great significance for solving cementing leakage, especially for oil and gas reservoir protection in non-homogeneous reservoirs.

Water-Based Polyurethane Dispersions: A Detailed Analysis of the Particle Charge Using Soft and Hard Particle Model.

Water-based polyurethane dispersions (PUDs) show a characteristic dependency of the electrophoretic mobility on the electrolyte concentration, which can be investigated by hard and soft particle models. For this purpose, additional information can be obtained by determining particle charges and electrostatic potentials. PUDs with different contents of an intrinsic ionic stabilizer and various polyol components were synthesized according to the acetone process. The particle charge was characterized by potentiometric acid-base titration, and the data of the titration curve were fitted assuming multiple functional groups with adaptable acid strengths. To investigate the electrostatic potentials, electrophoretic mobilities were measured as a function of electrolyte concentration and analyzed by soft and hard particle theory. Acid-base titration experiments indicated that not all detected ionic groups are located on the surface but are partly arranged inside the polymer particle, as evidenced by a significant decrease of the corresponding effective dissociation constant. The evaluation of the titration data and the electrokinetic experiments showed that the soft particle model of Ohshima is not suitable to reflect the actual particle charge. In contrast, the hard particle model can describe the measured electrophoretic mobility of the dispersions very well if the relaxation effect is taken into account. The dependency of the corresponding zeta potentials on the electrolyte concentration can be excellently modeled assuming a constant surface potential ψ0 and distance of the shear plane xs. Reasonable results are obtained for both parameters with only minor differences between the PUD series. Nonetheless, the electrokinetic surface charge densities calculated with respect to the surface potential are lower than expected from the titration results. Although our results indicate a more complex charge distribution in a peripheral layer, the hard particle model currently shows the best description of the electrokinetic behavior of the PUDs.

New Insights into the Mechanisms of Toxicity of Aging Microplastics.

Nowadays, synthetic polymer (plastic) particles are ubiquitous in the environment. It is known that for several decades microplastics (MPs) have been accumulating in the World Ocean, becoming available to a large variety of marine organisms. Particularly alarming is the accumulation of aging plastic particles, as the degradation processes of such particles increase their toxicity. The diverse display of negative properties of aging MPs and its effect on biota are still poorly understood. In this study, in vitro experiments modeling the interaction of pristine and UV-irradiated aging polypropylene (PP) fragments with hemocytes and mitochondria of bivalve mollusks Mytilus sp. were performed. The appearance of free radicals in the environment was recorded by spectral characteristics of indicator dyes-methylene blue (MB) and nitroblue tetrazolium (NBT). It was found that due to photooxidation, aging PP fragments sorbed more than threefold MB on their modified surface compared to pristine samples of this polymer. Using NBT, the formation of reactive oxygen species in seawater in the presence of pristine and photoactivated PP was recorded. It was also found that photodegraded PP fragments largely stimulated the development of lipid peroxidation processes in mitochondrial membranes and reduced the stability of hemocyte lysosome membranes compared to pristine PP fragments. In general, the results obtained concretize and supplement with experimental data the previously stated hypothesis of toxicity of aging MPs.

Experimental study into the sedimentation process of solids of different origin

Sedimentation refers to the first stage of wastewater treatment from mechanical impurities. Its rate depends on the density and particle size of impurities, as well as the density and viscosity of dispersion medium. In industrial sedimentation tanks, particle settling can occur in laminar, transient or turbulent modes. Aim. To establish the criterion equations and their coefficients for sedimentation processes of sand, glass and polyamide granules. Sedimentation of sand particles of 0.001– 0.003 m, spherical glass particles with the diameter of 0.0025–0.004 m and polyamide granules with the volume-surface mean diameter of 0.0022–0.003 m was carried out in a measured glass cylinder filled with distilled water. Each solid particle was measured, then, it came into contact with the water surface by means of tweezers, and released, starting to settle to the bottom of the cylinder under the action of gravity. A stopwatch was used to time the particle passaging between the marks of the measured cylinder. Calculations were performed using dimensional analysis. According to the test results, the dependences of the Reynolds number on the Archimedes number were established for the sedimentation of sand particles and polyamide granules in the transient mode, while spherical glass particles in the turbulent mode. In addition, the criterion equations of the solid particles sedimentation in the liquid were derived. The coefficients for these equations were experimentally determined. The equations and coefficients obtained in the study can be used in the design of settling tanks for mechanical treatment of wastewater to remove sand, glass and polymer particles.

Development of Solventless Pharmaceutical Technique for Manufacture of Pharmaceuticals

The aim of our study was to develop a solventless drug pelletization and polymer coating technique for pharmaceutical manufacturing. This review describes a dry coating technique using a mechanical powder processor and a V-shaped blender to produce coated pellets or tablets by mechanically mixing polymer particles and core materials (such as drug pellets and uncoated tablets) without the need for a solvent. First, aqueous latexes comprising colloidal polymethacrylates and ethylcellulose were solidified by freeze drying to produce polymer particles for the dry coating process. These particles and the cores were then subjected to mechanical powder processing or V-shaped blending to provide coated formulations with controlled-release characteristics. Polymer coating was achieved by using agglomerates comprising assembled colloidal polymer. The agglomerated polymer was easily pulverized during the mixing treatments due to its loose structure (the lack of close contacts between the colloidal particles), and the resulting fine polymer with high adhesiveness was deposited on the cores. Colloidal polymer dispersed in aqueous latex tends to coagulate in the freeze-drying process due to condensation of the dispersion, yielding dense agglomerates with poor coating characteristics. The presence of surfactants (such as sodium lauryl sulfate) in the latex can prevent adhesion between colloidal particles in the freeze-drying process, providing loosely structured agglomerates suitable for dry coating. Dry coating with a V-shaped blender could thus be achieved with these polymer particles instead of having to use a mechanical powder processor.

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)1Surfactant-free emulsion polymerization1 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),2Propargyl acrylate.2 styrene (Sty)3Styrene.3 and tert-butyl acrylate (t-BA),4Tert-butyl acrylate.4 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 anisotropies, 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).5Copper-catalyzed azide-alkyne cycloaddition5 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.

Advanced scattering techniques for characterisation of complex nanoparticles in solution

Nanoparticles are vital to a broad range of applications including commercial formulations, sensing and advanced material synthesis. Nanoparticles can come in a variety of shapes including cubes, polyhedra, rods, and prisms, and recent literature has demonstrated the importance of nanoparticle shape to downstream function (such as cellular uptake). While researchers routinely characterise nanoparticle shape using electron microscopy techniques, this generally requires drying of the samples. Many particles (e.g. lipid nanoparticles or polymer particles) change with drying, so complementary solution based techniques are needed. Scattering techniques can be used to characterise such nanoparticles in suspension, overcoming many of the limitations of other techniques. Here we review the current state of the art in the characterisation of complex nanoparticles (non-spherical and multi-layered) using advanced scattering techniques including light, X-ray, and neutron scattering. Recent improvements in instrument availability and data analysis makes these techniques much more accessible to researchers. This review provides an introduction to these techniques aimed at all researchers working with nanoparticles, in the hope that full characterisation of nanoparticles in solution becomes standard practice.