Polystyrene/melamine-formaldehyde hollow microsphere composite by self-assembling of latex particles at emulsion droplet interface

Preparation and modification of polymer microspheres, application in wastewater treatment: A review

The removal of various pollutants from water is necessary due to the increasing requirements for the removal of various pollutants from wastewater and the quality of drinking water. Polymer microspheres are regarded as exemplary adsorbent materials due to their high adsorption efficiency, excellent adsorption performance, and ease of handling. Herein, the advantages and disadvantages of different preparation methods, modifications, applications and the current research status of polymer microspheres are summarized at large. Furthermore, the enhanced performance of modified composite microspheres is emphasized, including adsorption efficiency, thermal stability, and significant improvements in physical and chemical properties. Subsequently, the current applications and potential of polymeric microspheres for wastewater treatment, including the removal of inorganic and organic pollutants, heavy metal ions, and other contaminants are summarized. Finally, future research directions for polymer microspheres are proposed, outlining the challenges and solutions associated with the application of polymer microspheres in wastewater treatment.

Novel encapsulation of water soluble inorganic or organic ingredients in melamine formaldehyde microcapsules to achieve their sustained release in an aqueous environment

A novel type of melamine formaldehyde microcapsule with a desirable barrier has been used to encapsulate water soluble ingredients, including potassium chloride (KCl) and allura red (dye) as models of an inorganic salt and organic molecule, respectively, via a facile method, and it has shown a sustained release of KCl and allura red for 12 h and 10 days in aqueous environment, respectively.

A novel type of melamine formaldehyde microcapsule has been used to encapsulate water-soluble ingredients: potassium chloride (KCl) and allura red (dye), which achieved a sustained release for 12 h and 10 days in aqueous environment respectively.

Self-assembled micelles based on branched poly(styrene-alt-maleic anhydride) as particulate emulsifiers

The self-assembled micelles of branched poly(styrene-alt-maleic anhydride) (BPSMA) are prepared and exhibit much superior emulsifying performance over the corresponding linear copolymer micelles as particulate emulsifiers.

Highly uniform hollow GdF3 spheres: controllable synthesis, tuned luminescence, and drug-release properties

In this paper, uniform hollow mesoporous GdF3 micro/nanospheres were successfully prepared by a facile two-step synthesis route without using any surfactant, catalyst, and further calcination process. The precursor Gd(OH)CO3 spheres are prepared by a coprecipitation process. After that, uniform and size-tunable GdF3 hollow spheres were easily coprecipitated with NaBF4 at the sacrifice of the precursor with low temperature and short reaction time. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution TEM, N2 adsorption/desorption, and up-conversion (UC) photoluminescence spectra were used to characterize the as-obtained products. It is found that the initial pH value and NaBF4/Gd(3+) molar ratios play important roles in the structures, sizes, and phases of the hollow products. The growth mechanism of the hollow spheres has been systematically investigated based on the Kirkendall effect. Under 980 nm IR laser excitation, UC luminescence of the as-prepared Yb(3+)/Er(3+)-codoped GdF3 hollow spheres can be changed by a simple adjustment of the concentration of the Yb(3+) ion. Enhanced red emission is obtained by introducing Li(+) ions in GdF3:Yb(3+)/Er(3+). Furthermore, a doxorubicin release experiment and a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide cytotoxicity assay reveal that the product has potential application in drug delivery and targeted cancer therapy.

Versatile fabrication of nanocomposite microcapsules with controlled shell thickness and low permeability

Novel ethyl phenylacetate (EPA)-loaded nanocomposite microcapsules with polyurea (PU) /poly (melamine formaldehyde) (PMF) shells were facilely and fabricated: by using silica nanoparticle-stabilized oil-in-water (o/w) emulsion template and subsequent interfacial reaction and in situ polymerization. SiO2 nanoparticles absorbed at the interface between oil and water to stabilize the o/w emulsions. The oil droplets containing EPA, isophorone diisocyanate (IPDI) and tolylene 2,4-diisocyanate-terminated poly (propylene glycol) (PPG-TDI) were subsequently reacted with MF prepolymer (pre-MF) dissolved in water phases. The interfacial reaction between pre-MF and IPDI produced interior PU walls. Meanwhile, the in situ polymerization of pre-MF generated exterior PMF walls. It was found that these in/out double walls were compact together. The resulting capsules had spherical shapes and rough exterior surfaces, and could be easily isolated, dried, and redispersed in epoxy resins. The size of the produced microcapsules was dependent on the concentration of SiO2 nanoparticles. The dynamic thermal gravimetric analysis (TGA) demonstrated that the capsules showed excellent thermal stability with little weight loss when exposed at 150 °C for 2 h. Interestingly, with a double PU/PMF shell, these capsules exhibited an extra-low permeability. Moreover, these microcapsules can also demonstrate exceelent magnetic responsiveness after introducing magnetic nanoparticles inside. We believe our microcapsules could be potential candidates in microcapsule engineering, self-healing composites, and drug-carrying systems.

The preparation of composite microsphere with hollow core/porous shell structure by self-assembling of latex particles at emulsion droplet interface

A submicrometer-scaled polystyrene/melamine-formaldehyde hollow microsphere composite was prepared by self-assembling of sulfonated polystyrene (SPS) latex particles at the interface of emulsion droplets and then being fixed in place using a hard melamine-formaldehyde (MF) composite layer. For control-released purposes, the influential factors that control the size and uniformity of the packed-droplets and the permeability of the composite shell, including the initial particle location, the hydrophilicity and the size of colloidal templates, the oil phase solvent and reserving time of emulsions after the addition of MF prepolymer, were further studied. Relatively uniform sized particle packed-droplets with an average diameter of 10 microm were obtained. The assembled SPS particles kept ordering and minimal conglutination after the preparation of composite microspheres, which allows of controlling the permeability from the interstices between the particles. Porous-mesh-structured MF composite layer was formed to further control the permeability. The morphology of emulsions and composite microspheres were characterized by optical microscopy, scanning and transmission electron microscopy.