Mingyuan Wu

Colloidal silver deposition onto functionalized polystyrene microspheres

This paper presents a facile method for the preparation of silver/polystyrene (Ag/PS) composite microspheres. PS microspheres with carboxyl and nitrile groups on the surfaces were synthesized via a two-step dispersion copolymerization of styrene, itaconic acid, and acrylonitrile in ethanol–water media. Ag/PS composite microspheres were prepared successively by addition of AgNO3 aqueous solution to the dispersion, absorbing to the surfaces of functional PS microspheres, and then reduction of Ag+ ions to silver nanoparticles by aqueous hydrazine hydrate. The results showed that Ag nanoparticles with size of about 50 nm were located on the shell of PS microspheres due to the combined interactions between the carboxyl and nitrile groups of PS microspheres and the in situ formed silver nanoparticles. The as-prepared Ag/PS microspheres showed good catalytic properties.

Facile fabrication of Janus magnetic microcapsules via double in situ miniemulsion polymerization

We describe a facile and flexible technique for fabricating Janus magnetic microcapsules via double in situ miniemulsion polymerization. Under a magnetic field, magnetic nanoparticles move to one side of the miniemulsion monomer droplets. After the monomers polymerize, an inorganic tetraethoxysilane (TEOS) phase is compressed and restricted as a liquid core due to the phase separation between TEOS and the growing polymer. After the monomers turn into a polymeric shell and the silica forms completely, the volume of the TEOS phase decreases dramatically leading to a hollow structure. Magnetic nanoparticles are chemically embedded in one side of the microcapsule shell and Janus magnetic microcapsules are fabricated efficiently and conveniently by a one-step method.

Facile fabrication of flower-like nanocomposite microparticles via seeded miniemulsion polymerization

Seed polymer/silica particles are synthesized by double in situ miniemulsion polymerization of methyl methacrylate (MMA) and hydrolysis–condensation of tetraethoxysilane (TEOS) under basic conditions simultaneously. Nanocomposite microparticles with a controlled morphology are fabricated from seed polymer/silica particles by the further miniemulsion polymerization of styrene. We have demonstrated that the seed PMMA/silica particles are cross-linked by nanosilica particles, which are dispersed homogeneously in the polymer matrix. The in situ formed silica nanoparticles acting as the cross-linking agent favor the formation of nonspherical nanocomposite microparticles with a flower-like structure. Furthermore composite microparticles of spherical morphology are obtained without γ-(trimethoxysilyl)propyl methacrylate (MPS). The addition of divinylbenzene (DVB) leads to a higher degree of cross-linking of the seed polymer particles, which favors the formation of peanut-like microparticles.

Facile fabrication of double-shelled hollow microspheres via double in situ miniemulsion polymerization

We describe a facile and flexible technique for fabricating double-shelled hybrid hollow microspheres with a controlled void size via in situ miniemulsion polymerization. After monomers polymerize the tetraethoxysilane phase is compressed and restricted as a liquid core leading to the formation of a hollow structure and silica shell. Furthermore, magnetic hollow microspheres are obtained conveniently.

Large-scale synthesis and characterization of magnetic poly(acrylic acid) nanogels via miniemulsion polymerization

This article provides a facile method for the large-scale preparation of magnetic poly(acrylic acid) (PAA) nanogels. Cross-linked polyacrylonitrile (PAN) nanoparticles were synthesized via a miniemulsion polymerization method using acrylonitrile (AN) and divinyl benzene (DVB) as the raw materials, and then PAA nanogels were obtained from the cross-linked PAN nanoparticles under basic conditions. The structure and morphologies of PAN nanoparticles, PAA nanogels, and magnetic PAA nanogels were characterized by Fourier-transformed infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and dynamic light scattering equipment (DLS), respectively. The pH-responsive property of PAA nanogels was investigated by measuring their swelling–deswelling behavior under different pH buffer solutions. The results showed that the obtained PAN nanoparticles were of uniform spherical morphology with a wrinkled surface and had a narrow size distribution with an average size of 105 nm in diameter. PAA nanogels were regular spherical particles with an average particle size of 230 nm in diameter. The PAA nanogels demonstrated excellent pH-responsive properties in different pH buffer solutions. After the addition of γ-(trimethoxysilyl)propyl methacrylate (MPS) modified magnetic nanoparticles, magnetic PAA microgels were fabricated successfully.

Facile fabrication of poly(acrylic acid) hollow nanogels via in situ Pickering miniemulsion polymerization

This communication presents a facile and large-scale fabrication of poly(acrylic acid) (PAA) hollow nanogels via an in situ Pickering miniemulsion polymerization method. Cross-linked polyacrylonitrile (PAN) nanoparticles with a hollow structure were prepared by using a hydrophobic solvent as the liquid core. The complete hydrolysis reaction process of the PAN shell leads to the successful formation of hollow PAA nanogels. Furthermore, magnetic hollow microgels are obtained conveniently.

Raspberry-like nanocomposite microsphere via Double In situ miniemulsion polymerization using interfacial redox initiator system

Abstract

Synthesis and multi-responsiveness of poly(N-vinylcaprolactam-co-acrylic acid) core–shell microgels via miniemulsion polymerization

This paper reported a facile strategy to the large scale synthesis of multi-responsive core–shell microgels via seed miniemulsion copolymerization of N-vinylcaprolactam (NVCL) and acrylonitrile (AN) using 2,2′-azobis(2-methylpropionitrile) (AIBN) and divinylbenzene (DVB) as the initiator and the cross-linker, respectively. The core–shell microspheres were initially prepared via miniemulsion polymerization with polyacrylonitrile (PAN) as the core and poly(N-vinylcaprolactam) (PNVCL) as the shell. Then P(NVCL-co-AA) microgels were obtained by hydrolysis of the PAN core under base conditions. The sizes, morphologies and swelling behavior of the as-obtained microparticles were systematically investigated by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analyses (TGA). The results showed that the obtained microgels were spherical in shape with an average size of about 100 nm. P(NVCL-co-AA) microgels had a core–shell morphology with PAA as the core and PNVCL as the shell. The contents of NVCL and DVB had an effect on the structure of microgels and hydrodynamic diameters, respectively. The resultant microgels can reversibly swell and shrink in response to pH and temperature variation, demonstrating great promise for potential applications in drug delivery and bio-sensors.

Preparation and Application of Functional Inorganic/Polymer Hollow Microspheres Via Double In Situ Mini-Emulsion Polymerization

Silica/polymer hollow microspheres were prepared via double in situ mini-emulsion polymerization by taking advantage of phase separation between the growing polymer and inorganic TEOS phase. Then hybrid hollow microspheres were surface modified by the addition of GMA during the process of polymerization. The obtained surface–functional hybrid hollow microspheres were applied as a filler in polysulfide sealant system. The inorganic/polymer hollow microspheres were characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), thermogravimetric/derivative thermal gravimetric analysis (TGA/DTG), and thixotropic experiment, respectively. The results showed that the as-prepared inorganic/polymer microspheres had a hollow structure and the size was in the range of 200–600 nm. The thixotropy and heat resistance properties of polysulfide sealant were improved after the addition of hybrid hollow microspheres.