Morphological Control of Multihollow Polymer Latex Particles through a Controlled Phase Separation in the Seeded Emulsion Polymerization

In this work, we first reported that the phase separation can take place both inside and outside of a multihollow-structured cross-linked seed microspheres swollen by styrene monomers in water during the radiation-induced seeded emulsion polymerization. The phase separation process in these two opposite directions will determine the morphology of final latex particles. First, sulfonated cross-linked polystyrene (SCPS) seed microspheres were swollen by styrene in water. Water will permeate into the SCPS seed microspheres during the swelling process, forced by the osmotic pressure produced by the strong hydrophilicity of the sulfonic acid groups. New aqueous phases are created and stabilized by the hydrophilic −SO₃H groups, resulting in a multihollow structure of swollen SCPS seed microspheres. When the polymerization of styrene is induced by ⁶⁰Co γ-ray radiation, the phase separation of newly formed polystyrene phase will occur at the seed microsphere-water interface inside and/or outside of the SCPS seed microspheres through adjusting the diameter of seed microsphere, the content of cross-link agent, and the sulfonation degree of SCPS seed microspheres. As a result, SCPS latex particles with a variety of special morphologies, such as spherical multihollow, plum-like, and walnut-like latex particles were obtained. The results of this study provide not only a simple and interesting way to design and synthesize multihollow polymer latex particles with controllable surface morphologies but also a better understanding on phase separation mechanism during the swelling and polymerization of monomers in cross-linked amphiphilic polymer networks

Formation of Cagelike Sulfonated Polystyrene Microspheres via Swelling-Osmosis Process and Loading of CdS Nanoparticles

In this report, we studied the formation mechanism of cagelike polymer microspheres fabricated conveniently and efficiently through a swelling-osmosis process of sulfonated polystyrene (SPS) microspheres in a ternary mixed solvent (water/ethanol/heptane). The scanning electron microscopy and transmission electron microscopy observations indicated that the morphology of the final cagelike SPS microspheres is mainly controlled by the composition of the mixed solvent and the swelling temperature. Considering the solubility parameters of related reagents and the low interface tension of heptane and the aqueous solution of ethanol (only 6.9 mN/m), we confirm that the porogen procedure starts from the swelling of SPS microspheres by heptane, followed by the osmosis process of water molecules into the swollen SPS microspheres forced by the strong hydrophilicity of −SO₃H group. The water molecules permeated into SPS microspheres will aggregate into water pools, which form the pores after the microspheres are dried. These prepared cagelike SPS microspheres are further served as the scaffold for the in situ generated CdS nanoparticles under γ-ray radiation. The CdS/SPS composite microspheres show good fluorescence performance. This work shows that the cagelike SPS microspheres have a wide industrial application prospect due to their economical and efficient preparation and loading nanoparticles

Fabrication and Morphology of Spongelike Polymer Material Based on Cross-Linked Sulfonated Polystyrene Particles

A novel spongelike polymer material has been fabricated by γ-ray induced polymerization of methylmethacrylate (MMA) in an emulsion containing cross-linked sulfonated polystyrene (CSP) particles. Scanning electron microscopy (SEM) images reveal that the spongelike structure is made up of interlinked nanosized PMMA particles with micrometer-sized CSP-PMMA particles embedded inside. The nitrogen adsorption isotherm discloses that the spongelike material has a high specific surface area of 29 m²/g and a narrow pore size distribution of 60–120 nm. The formation mechanism is discussed in this paper, which indicates that the key steps to form the spongelike material include a Pickering emulsion stabilized by the CSP particles, followed by the swelling process of MMA into these particles. This approach offers a more convenient alternative to prepare polymeric spongelike material without any etching procedure

Fabrication of High-Performance Magnetic Lysozyme-Imprinted Microsphere and Its NIR-Responsive Controlled Release Property

The preparation of efficient and practical biomacromolecules imprinted polymer materials is still a challenging task because of the spatial hindrance caused by the large size of template and target molecules in the imprinting and recognition process. Herein, we provided a novel pathway to coat a NIR-light responsive lysozyme-imprinted polydopamine (PDA) layer on a fibrous SiO₂ (F-SiO₂) microsphere grown up from a magnetic Fe₃O₄ core nanoparticle. The magnetic core–shell structured lysozyme-imprinted Fe₃O₄@F-SiO₂@PDA microspheres (MIP-lysozyme) can be easily separated by a magnet and have a high saturation adsorption capacity of lysozyme of 700 mg/g within 30 min because of the high surface area of 570 m²/g and the mesopore size of 12 nm of the Fe₃O₄@F-SiO₂ support. The MIP-lysozyme microspheres also show an excellent selective adsorption of lysozyme (IF > 4). The binding thermodynamic parameters studied by ITC proves that the lysozyme should be restricted by the well-defined 3D structure of MIP-lysozyme microspheres. The MIP-lysozyme can extract lysozyme efficiently from real egg white. Owing to the efficient NIR light photothermal effect of PDA layer, the MIP-lysozyme microspheres show the controlled release property triggered by NIR laser. The released lysozyme molecules still maintain good bioactivity, which can efficiently decompose <i>E. coli</i>. Therefore, this work provides a novel strategy to build practical NIR-light-responsive MIPs for the extraction and application of biomacromolecules

Effect of γ‑Ray-Radiation-Modified Graphene Oxide on the Integrated Mechanical Properties of PET Blends

The surface modification of graphene oxide (GO) determines the interactions between GO and polymers, which possibly produces a significant impact on the mechanical properties of polymer. Here, GO was first modified with poly­(glycidyl methacrylate) (PGMA) and triethylenetetramine (TTA) through γ-ray radiation. Then, a tiny small amount (0.04%) of the prepared modified GO was filled with a PET/ethylene-methyl acrylate-glycidyl methacrylate random terpolymer (PET/ST2000) blend. The morphological analyses on these filled PET blends confirmed that the surface chemical structure of GO had a crucial impact on the mechanical property of the blend. The chemical bonding between GO and ST2000 was more efficient in improving the dispersibility of GO and the compatibility between PET and ST2000, leading to a 2.5-fold increase in the impact strength, along with a slight increase in tensile strength. However, the addition of reduced GO lacking polar groups caused fatal damage in the mechanical property of the blend