Surface Microstructure Regulation of Porous Polymer Microspheres by Volume Contraction of Phase Separation Process in Traditional Suspension Polymerization System

Xanthium-Inspired Microsphere Morphology Depends on the Dual Self-Assembly Behavior of Macromolecules

The self-assembly of macromolecular segments promotes the fabrication of polymer microspheres with multiple morphologies. Inspired by the xanthium shells, A dual-driven self-assembly method have defined that enables the construction of multi-dimensional morphologies on the microsphere surface at emulsion-confined interfaces. The two driving forces are derived from the phase separation caused by the immiscibility of macromolecular segments and the different interactions between chain segments of different hydrophilicity and water molecules. The synergistic effects of these two forces, the xanthium shell structure is constructed on the microsphere surface, enabling the development of increasingly complex superstructure. This scalable approach provides extensive potential for the self-assembly technology of block copolymers with opposite properties.

Density Matching for Microencapsulation of Field Responsive Suspensions of Non-Brownian Microparticles

When forming composite microcapsules through the emulsification of a dispersed phase laden with microparticles, one will find that the microparticles become irreversibly embedded in the resulting microcapsule membrane. This phenomenon, known as Pickering stabilization, is detrimental when the end function of the microcapsules relies on the mobility of encapsulated microparticles within the capsule core. In this work, a robust microencapsulation route using density matching of non-Brownian microparticles in a binary solvent is shown to easily and effectively encapsulate particles, with >90% of particles retaining mobility within the microcapsules, without the necessity for prior chemical/physical modifications to the microparticles. This is proposed as a generalized method to be used for all manner of particle chemistries, shapes, and sizes.

Preparation of Surface-Wrinkled Silica-Polystyrene Colloidal Composite Particles

In this work, we report a facile emulsion swelling route to prepare surface-wrinkled silica-polystyrene (SiO2-PS) composite particles. Submicrometer-sized, near-spherical SiO2-PS composite particles were first synthesized by dispersion polymerization of styrene in an ethanol/water mixture, and then, surface-wrinkled SiO2-PS particles were obtained by swelling the SiO2-PS particles with a toluene/water emulsion and subsequent drying. It is emphasized that no surface pretreatment on the SiO2-PS composite particles is required for the formation of the wrinkled surface, and the most striking feature is that the surface-wrinkled particle was not deformed from a single near-spherical SiO2-PS composite particle but from many ones. The influence of various swelling parameters including toluene/particle mass ratio, surfactant concentration, stirring rate, swelling temperature, swelling time, and silica size on the morphology of the composite particles was studied. This method represents a new paradigm for the preparation of concave polymer colloids.

The Role of Microsphere Structures in Bottom-Up Bone Tissue Engineering

Bone defects have caused immense healthcare concerns and economic burdens throughout the world. Traditional autologous allogeneic bone grafts have many drawbacks, so the emergence of bone tissue engineering brings new hope. Bone tissue engineering is an interdisciplinary biomedical engineering method that involves scaffold materials, seed cells, and "growth factors". However, the traditional construction approach is not flexible and is unable to adapt to the specific shape of the defect, causing the cells inside the bone to be unable to receive adequate nourishment. Therefore, a simple but effective solution using the "bottom-up" method is proposed. Microspheres are structures with diameters ranging from 1 to 1000 µm that can be used as supports for cell growth, either in the form of a scaffold or in the form of a drug delivery system. Herein, we address a variety of strategies for the production of microspheres, the classification of raw materials, and drug loading, as well as analyze new strategies for the use of microspheres in bone tissue engineering. We also consider new perspectives and possible directions for future development.

Synthetic Strategies for Polymer Particles with Surface Concavities

Over the past decade or so, there has been increasing interest in the synthesis of polymer particles with surface concavities, which mainly include golf ball-like, dimpled and surface-wrinkled polymer particles. Such syntheses generally can be classified into direct polymerization and post-treatment on preformed polymer particles. This review aims to provide an overview of the synthetic strategies of such particles. Some selected examples are given to present the formation mechanisms of the surface concavities. The applications and future development of these concave polymer particles are also briefly discussed. This article is protected by copyright. All rights reserved.

Wrinkled Fe3O4@C magnetic composite microspheres: Regulation of magnetic content and their microwave absorbing performance

In this work, we develop a novel synthetic strategy for wrinkled magnetic composite microspheres (Fe₃O₄@C). Firstly, hydrophobic oleic acid modified Fe₃O₄ (OA-Fe₃O₄) nanoparticles acted as the magnetic component are prepared by synchronous modification coprecipitation method. The macromolecular emulsifier with initiating activity is obtained by means of soap-free emulsion polymerization under the presence of 1,1-diphenylethylene (DPE). Then, interfacial polymerization is employed to synthesis Fe₃O₄@polymethylglycidyl ester/divinylbenzene composite microspheres (Fe₃O₄@PGMA/DVB). Fe₃O₄@C composite microspheres are obtained by vacuum carbonization of the microspheres. The effect of magnetic content on the microwave absorbing properties of Fe₃O₄@C composite microspheres is explored. The results show that Fe₃O₄@C composite microspheres exhibit the excellent application performance at the Fe₃O₄ content of 0.15 g. The reflection loss can reach -53.7 dB at only thickness of 1.7 mm. The Maximum effective absorption bandwidth is up to 5.26 GHz with a thickness of 1.9 mm. The microwave attenuation mechanism of Fe₃O₄@C composite microspheres is revealed. The excellent absorbing performance is attributed to the enhanced interfacial polarization ability, the surface wrinkled structure and the good synergy between dielectric and magnetic losses. This work provides an effective strategy for the design and preparation of new magnetic composite materials.

Preparation and Microwave Absorption Properties of C@Fe3O4 Magnetic Composite Microspheres

In this work, C@Fe₃O₄ magnetic microspheres were designed and prepared by a novel strategy, and the microwave absorption properties of the materials were investigated. Four kinds of monodisperse P(MAA/St) microspheres with different carboxyl content were synthesized via facile dispersion polymerization. The Fe₃O₄ nanoparticles were grown on the surface of P(MAA/St) to obtain P(MAA/St)@Fe₃O₄ microspheres. Using P(MAA/St)@Fe₃O₄ as the precursors, after vacuum carbonization, C@Fe₃O₄ were obtained. It was observed that the carboxyl content on the microspheres’ surface increased with the increasing of MAA, which made the magnetic content and maximum specific saturation magnetization of P(MAA/St)@Fe₃O₄ and C@Fe₃O₄ increase. The obtained four kinds of C@Fe₃O₄ microspheres had a particle size range of 4–6 μm. The microwave absorption properties indicated that the magnetic content made a difference to the microwave absorption properties of C@Fe₃O₄ magnetic microspheres. The microwave absorption properties of materials were determined by controlling dielectric loss, magnetic loss and impedance matching. C@Fe₃O₄ microspheres exhibited excellent microwave absorption properties. The maximum reflection loss could reach −45.6 dB at 12.8 GHz with 3 mm in thickness. The effective bandwidth was 5.9 GHz with RL < −10 dB. Therefore, C@Fe₃O₄ microspheres were lightweight and efficient microwave absorption materials.