Monodisperse Polymer Microspheres Research Articles

Review on Preparation of Polystyrene Microspheres

The traditional preparation methods of polystyrene microspheres are emulsion polymerization and suspension polymerization. The diameter of the microspheres prepared by the former is generally less than 0.5 m, and the diameter of the microspheres prepared by the latter is about several hundred microns and is difficult to control. With the continuous development of science and technology, scientists have found multiple methods to prepare micron-sized monodisperse polymer microspheres in recent years. Such as soap-free or low-soap emulsion method, dispersion polymerization method, liquid-phase synthesis method. The four preparation methods of dispersion polymerization, emulsion polymerization, liquid-phase synthesis, suspension polymerization and their respective advantages and disadvantages are discussed in detail, and the prospect of synthetic application is prospected.

Photo‐induced fusion of monodisperse polymer microspheres: A novel strategy for constructing topological microsphere clusters with improved stability

AbstractThe preparation of monodisperse azobenzene (Azo) polymer microspheres by dispersion polymerization was reported. The photo‐induced fusion of Azo polymer microspheres was successfully achieved during the process of reversible trans‐cis‐trans photoisomerization of Azo units, and induced various unique “microsphere molecular” clusters or “microsphere polymers”. Encouraged by this interesting phenomenon, microsphere clusters of different topological structures were stabilized by the in situ acetal cross‐linking chemistry. The photo‐induced fusion polymerization of monodisperse polymer microspheres provides a new strategy for designing photo‐responsive clusters and allows for control over the mechanical properties of microspheres with high spatiotemporal resolution.

Microfluidic Coupling of Step Emulsification and Deterministic Lateral Displacement for Producing Satellite-Free Droplets and Particles

Step emulsification, which uses a geometry-dependent mechanism for generating uniformly sized droplets, has recently gained considerable attention because of its robustness against flow fluctuations. However, like shear-based droplet generation, step emulsification is susceptible to impurities caused by satellite droplets. Herein, we demonstrate the integration of deterministic lateral displacement (DLD) to separate the main and satellite droplets produced during step emulsification. Step-emulsification nozzles (16 μm deep) in the upstream region of the proposed device were arrayed on the sidewalls of the main channel (91 μm deep). In the downstream region, the DLD micropillars were arrayed periodically with a critical diameter (cut-off value for size-based separation) of 37 μm. When an acrylate monomer and aqueous polyvinyl alcohol solution were infused as the dispersed and continuous phases, respectively, the nozzles produced monodisperse main droplets in the dripping regime, with an average diameter of ~60 μm, coefficient of variation (CV) value below 3%, and satellite droplets of ~3 μm. Upon entering the DLD region near the sidewall, these main and satellite droplets were gradually separated through the pillars based on their sizes. Finally, off-chip photopolymerization yielded monodisperse polymeric microspheres with an average diameter of 55 μm and a CV value of 2.9% (n = 202).

Synthesis of an Ethylenediamine-Modified Hypercrosslinked Polymer and its Preliminary Study for Antipyrine and Pamabrom Extraction

Emerging contaminants (EC) are naturally occurring or synthetic chemicals that may enter the environment and cause adverse effects to aquatic and human health. EC consist of pharmaceuticals, pesticides, organic chemicals and personal care products that present in water sources at low concentrations (μg/L), hence, they are not widely monitored in the environment. Pharmaceuticals contain biologically-active components that pollute water courses. These generally originate from human waste or the uncontrolled release of residues from chemical plants. The removal of pharmaceutical compounds from water can be carried out using polymeric materials with high specific surface areas and good selectivity due to the presence of accessible active functional groups. In the present work, the synthesis and characterizations of microspheres, acrylonitrile-co-divinylbenzene-80-co-vinylbenzylchloride(AN-co-DVB-80-co-VBC) terpolymers with weak-anion-exchange (WAX) character and high porosity have been successfully carried out. The polymeric microspheres were synthesized by precipitation polymerization and subsequently hypercrosslinked (HXL) via a Friedel-Crafts reaction. The HXL terpolymer was then chemically modified with 1,2-ethylenediamine (EDA) to incorporate diamine functional groups, which improved the selectivity of the HXL microspheres towards polar compounds. Fourier Transform-Infrared (FT-IR) spectra of the EDA-modified HXL terpolymer showed that the nitrile groups derived from AN units were utilized due to the presence of diamine groups along the polymeric chains, indicating that the chemical modification was successful. The microanalysis showed that the chlorine content of the polymer was significantly decreased after hypercrosslinking, indicating that the reaction was successful. The nitrogen content increased after chemical modification with EDA, indicating successful chemical modification of the microspheres. The polymers were in the form of spherical monodisperse polymer microspheres with mean particle diameters of ~7.00 μm. The highest observed specific surface areas (SSAs) of the HXL terpolymer and EDA-modified HXL terpolymer were 2,274 m²/g and 503 m²/g, respectively. The microspheres were utilized to extract the pharmaceutical compounds antipyrine and pamabrom from aqueous solution using the dispersive solid phase extraction (DSPE) method. The extraction analysis was carried out by Gas Chromatography–Mass Spectrometry (GC-MS). The influence of adsorbent dosage, extraction time and elution time were studied to evaluate the performance of the adsorbent in the extraction of antipyrine and pamabrom from aqueous solution. It can be concluded that EDA-modified HXL poly(AN-co-DVB-80-co-VBC) was more favourable towards the extraction of antipyrine, which had a maximum extraction efficiency (EE%) of 95%, compared to that of pamabrom (maximum EE% of 54%).

Studies on Preparation, Characterization and Application of Porous Functionalized Glycidyl Methacrylate-Based Microspheres.

A one-step swelling and polymerization technique was used in the synthesis of porous glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA) monodisperse polymeric microspheres. The polystyrene (PS) seed obtained in the dispersion polymerization was used as a shape template. The presence of epoxide rings in the chemical structure of microspheres enables their post-polymerization chemical modifications involving: the Diels-Alder reaction with sodium cyclopentadienide and maleic anhydride, the reaction with 4,4′-(bismaleimido)diphenylmethane, and the thiol-Michael reaction with methacryloyl chloride and 2-mercaptopropionic acid. Changing the reaction mixture composition—the amounts of crosslinking monomer and PS seed as well as the type and concentration of porogen porous microspheres of different porous structures were obtained. Their porous structures were characterized in the dry and swollen states. The copolymers obtained from the equimolar monomers mixture modified in the above way were applied as the column packing materials and tested in the reverse-phase HPLC (High-Performance Liquid Chromatography). A few factors influencing morphology and porous structure of microspheres were studied.

Preparation of Large-sized Microencapsulated Phase Change Materials Through Pickering Emulsion Stabilized by Monodisperse Polymer Microspheres

Preparation of Large-sized Microencapsulated Phase Change Materials Through Pickering Emulsion Stabilized by Monodisperse Polymer Microspheres

Microfluidic preparation of thiol-containing monodisperse polymer microspheres and their adsorption of Pb2+ in water

A novel polymerizable monomer containing carbon-carbon double bond and disulfide bond, 2-(((2-(pyridin-2-yldisulfanyl)ethoxy)carbonyl)amino) ethyl acrylate (PDSECAE), was first designed and synthesized, and then used to prepare thiol-containing monodisperse polymer microspheres with different sizes from 20 μm to 500 μm by means of microfluidic technique, UV-induced polymerization and dithiothreitol reduction in sequence. The chemical structures of PDSECAE and the microspheres were confirmed by NMR, FTIR and RAMAN, and the thiol content was determined by UV–vis spectrophotometer. Having the largest specific surface area, microspheres of 20.0 μm in diameter were utilized in adsorption of Pb2+ in water, and the maximum adsorption capacity reached 104.4 mg/g at pH 6.0 and 25 °C. After the adsorbed Pb2+ was removed by ethylenediaminetetraacetic acid disodium salt, the regenerated thiol-containing microspheres could be reused and their adsorption capacity still remained 85% of its initial value after 5 recycles. Efficient adsorption performance and easy reusability make the thiol-containing polymer microspheres show promising applications to adsorption of heavy metal ions.

Monodisperse poly(methyl methacrylate) microspheres with tunable carboxyl groups on the surface obtained by photoinitiated RAFT dispersion polymerization.

Surface-functional polymeric microspheres have broad applications in numerous areas. Herein, monodisperse polymeric microspheres with tunable carboxy groups on the surface are prepared by photoinitiated RAFT dispersion polymerization using binary mixtures of two macromolecular chain transfer agents (macro-CTAs). The obtained carboxyl-functionalized polymeric microspheres can be further used to induce the formation of hollow inorganic/organic composites and the biomineralization of inorganic crystals.

Microfluidic preparation of monodisperse polymeric microspheres coated with silica nanoparticles

The synthesis of organic-inorganic hybrid particles with highly controlled particle sizes in the micrometer range is a major challenge in many areas of research. Conventional methods are limited for nanometer-scale fabrication because of the difficulty in controlling the size. In this study, we present a microfluidic method for the preparation of organic-inorganic hybrid microparticles with poly (1,10-decanediol dimethacrylate-co-trimethoxysillyl propyl methacrylate) (P (DDMA-co-TPM)) as the core and silica nanoparticles as the shell. In this approach, the droplet-based microfluidic method combined with in situ photopolymerization produces highly monodisperse organic microparticles of P (DDMA-co-TPM) in a simple manner, and the silica nanoparticles gradually grow on the surface of the microparticles prepared via hydrolysis and condensation of tetraethoxysilane (TEOS) in a basic ammonium hydroxide medium without additional surface treatment. This approach leads to a reduction in the number of processes and allows drastically improved size uniformity compared to conventional methods. The morphology, composition, and structure of the hybrid microparticles are analyzed by SEM, TEM, FT-IR, EDS, and XPS, respectively. The results indicate the inorganic shell of the hybrid particles consists of SiO2 nanoparticles of approximately 60 nm. Finally, we experimentally describe the formation mechanism of a silica-coating layer on the organic surface of polymeric core particles.

Preparation of the monodispersed carboxyl-functionalized polymer microspheres with disproportionated rosin moiety and adsorption of methylene blue

Carboxyl-functionalized polymer microspheres with a rosin moiety were prepared through dispersion polymerization using styrene, disproportionated rosin ester, and methylacrylic acid as raw materials. The effects of dispersion medium (ethanol/water) ratio, monomer mass proportion and initiator concentration on the polymer microspheres were studied. Scanning electron microscopy, laser particle size analysis, thermogravimetric analysis and Fourier transform infrared spectroscopy were used to characterize the microspheres, and their carboxyl contents were determined by the conductance titration method. The adsorption of methylene blue of the microspheres was also investigated. The results showed that rosin-based carboxyl-functionalized polymer microspheres were successfully synthesized. The microspheres exhibited smooth, spherical shapes with good monodispersity and high thermal stability. The carboxyl content of the microspheres prepared under optimum conditions was 0.089 mmol·g−1, with the average particle size approximately 950 nm. With increasing carboxyl contents of the polymer microspheres, their methylene blue adsorption capacities increased. The maximum methylene blue adsorption capacity of the microspheres was 59.55 mg·g−1 in the highest carboxyl content.

High efficiency and fast separation of active proteins by HIC chromatographic pie with sub-2 μm polymer packings

This paper reports the development of hydrophobic interaction chromatography (HIC) by synthesizing sub-2 μm polymer packings which was packed into a chromatographic pie for fast separation of native proteins at low pressures demonstrating high efficiency. Using styrene as monomer and ethylene dimethacrylate (EDMA)as swelling agent, the polystyrene seeds with an average particle size of 0.8 μm and monodisperse polymeric microspheres with a particle size of 1.5–5.0 μm were synthesized through dispersion polymerization and one-step swelling method, respectively. In order to separate active proteins, the microspheres were modified to hydrophobic chromatographic packings through covalent bonding with benzene methanol. Compared with the traditional column chromatography, the sub-2 μm polymer packings in chromatographic pie exhibited higher column efficiency for protein separation at lower column pressures, even at higher flow rates. The van Deemter curve showed that the flow rate had insignificant effect on column efficiency of chromatographic pie. Seven example proteins were clearly separated within 3 min at a flow rate of 10 mL/min. The applicability of this method was further demonstrated by the separation of human serum samples. The results indicated that this chromatographic mode can be potentially applied for the fast separation of complex active proteins, such as protein drugs from natural products.

Carboxyl-Functionalized Polymeric Microspheres Prepared by One-Stage Photoinitiated RAFT Dispersion Polymerization.

Herein, we report a photoinitiated reversible addition-fragmentation chain transfer (RAFT) dispersion copolymerization of methyl methacrylate (MMA) and methyl methacrylic (MAA) for the preparation of highly monodisperse carboxyl-functionalized polymeric microspheres. High rates of polymerization were observed, with more than 90% particle yields being achieved within 3 h of UV irradiation. Effects of reaction parameters (e.g., MAA concentration, RAFT agent concentration, photoinitiator concentration, and solvent composition) were studied in detail, and highly monodisperse polymeric microspheres were obtained in most cases. Finally, silver (Ag) composite microspheres were prepared by in situ reduction of AgNO3 using the carboxyl-functionalized polymeric microspheres as the template. The obtained Ag composite microspheres were able to catalyze the reduction of methylene blue (MB) with NaBH4 as a reductant.

Progress in Preparation of Monodisperse Polymer Microspheres

The monodisperse crosslinked polymer microspheres have attracted much attention because of their superior thermal and solvent resistance, mechanical strength, surface activity and adsorption properties. They are of wide prospects for using in many fields such as biomedicine, electronic science, information technology, analytical chemistry, standard measurement and environment protection etc. Functional polymer microspheres prepared by different methods have the outstanding surface property, quantum size effect and good potential future in applications with its designable structure, controlled size and large ratio of surface to volume. Scholars of all over the world have focused on this hot topic. The preparation method and research progress in functional polymer microspheres are addressed in the paper.

Immobilization of Trametes versicolor laccase on different PGMA‐based polymeric microspheres using response surface methodology: Optimization of conditions

ABSTRACTEnzymatic immobilization is a versatile alternative to improve enzyme stability and enable its reuse. In this study, the change in the immobilized enzyme properties due to the type of functional group on the carrier was evaluated. For that, monodisperse polymeric microspheres with two functional groups widely used in laccase immobilization—oxirane [poly(glycidyl methacrylate) (PGMA)] and hydrazide—were synthesized by dispersion polymerization to covalently immobilize the laccase Trametes versicolor. Using a response surface methodology, laccase immobilization was optimized for each microsphere type. As a result, laccase immobilization on PGMA carriers appears to broaden the pH and temperature ranges, storage stability, and reusability compared to free and hydrazide enzymes. These aforementioned characteristics indicate that PGMA microspheres could act as an ideal support for enzyme immobilization in biotechnological applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45249.

RAFT of sulfobetaine for modifying poly(glycidyl methacrylate) microspheres to reduce nonspecific protein adsorption

The minimization of nonspecific protein adsorption is a crucial step in the development of bioseparation processes, immunoassays, and affinity diagnostics. Among the numerous biomaterials, polyzwitterions are known to effectively suppress protein and cell adhesion. This article describes the formation of monodisperse polymer microspheres coated with polysulfobetaine with the aim to limit nonspecific adsorption of bovine serum albumin (BSA) as a model protein. In this process, 2-μm poly(glycidyl methacrylate) (PGMA) microspheres were prepared by dispersion polymerization. To render the microspheres hydrophilic and biocompatible, [3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide (MPDSAH) was grafted from the surface by reversible addition-fragmentation chain transfer (RAFT) polymerization. Elemental analysis of the modified microspheres revealed up to 20 wt % of poly{[3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonimum hydroxide} (PMPDSAH). The microspheres were characterized in terms of particle size, morphology, and zeta potential. The amount of BSA nonspecifically adsorbed on the PMPDSAH-modified microspheres decreased to half of that captured on the unmodified PGMA microspheres. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2273–2284

Synthesis and Characterization of Hydroxyl-Functionalized Polystyrene Microspheres With Monodispersity

Hydroxyl-functionalized polystyrene (HFPS) microspheres were prepared by the copolymerization of styrene (St) and hydroxyethyl acrylate (HEA) via dispersion polymerization in the absence of steric stabilizers. The copolymerization was conducted with V-50 as an initiator. The effect of initiator concentration, HEA amount, and medium composition on the average diameters and coefficient variations of HFPS microspheres were systematically investigated. The particle morphology, the average diameters, the surface N content, and the particle size distribution curves were measured by SEM, XPS, and laser particle size analyzer. The results indicated that monodisperse HFPS microspheres with diameter of 0.6–1.0 μm could be successfully generated by dispersion polymerization of St and HEA without steric stabilizers. Therefore, overall, the present manuscript provided a simple route to generate monodisperse hydroxyl-functionalized polymer microspheres.

Novel Approach to Synthesis of Monodisperse Polymeric Microspheres: Heterophase Polymerization of Styrene and Methyl Methacrylate in Presence of Water-Insoluble Functional PDMSs

Water-insoluble polydimethylsiloxanes (PDMSs) with functional organic substituents at the silicon atom are promising surface-active substances for the synthesis of monodisperse polymeric microspheres. In this regard a number of PDMS oligomers bearing different functional chain ends (amino, carboxylic and epoxy groups) were synthesized by conventional approaches. Solubility of PDMS in both the monomers (styrene (St) or methyl methacrylate (MMA)) and water as well as their surface-active properties at the water-toluene interface were investigated. Heterophase polymerization of St and MMA was carried out in the presence of functional PMDS and the resulting suspensions of polymeric microspheres were characterized using scanning electron microscopy (SEM). It was shown that the polymeric suspensions obtained have a very narrow particle size distribution and high stability in electrolyte solutions. The mechanism of the interfacial layer formation which explains the observed results is proposed.

A green protocol to prepare monodisperse poly(TMPTMA–styrene) microspheres by photoinitiated precipitation polymerization in low-toxicity solvent

To prepare monodisperse polymer microspheres under mild conditions, a green protocol is set up by means of photoinitiated precipitation polymerization. The work is carried out with three novel parameters, including: new type crosslinker of trifunctionality, low-toxicity solvent, and ambient temperature. Firstly, trihydroxymethyl propane triacrylate (TMPTMA) is selected as the most suitable crosslinker to prepare microspheres under ambient temperature, after comparing the morphology of its polymerization products with those of other two similar crosslinkers, i.e., trimethylolpropane triacrylate and ethoxylated trimethylolpropane triacrylate. In addition, as high as possible concentrations of TMPTMA and styrene are attempted to harvest the largest amounts of microspheres; however, a threshold of monomer concentration is found at 6 %. One kind of low-toxicity solvent, i.e., ethanol, is used as the reaction media to replace the commonly used toxic organic solvents, and it is proven to be the near Θ solvent for the present polymerization. Observation from scanning electron microscopy indicates that photoinitiation is an effective way to control the growth of microspheres, and highly monodisperse microspheres of 2.67 μm are achieved at polymerization time of 120 h. Finally, the reactive vinyl groups on microsphere surface are confirmed, which indicate that the microspheres from this green protocol is in favor of further functionalization and bio-medical application.

Synthesis of Monodisperse Polystyrene Microspheres by Seeding Polymerization

Monodisperse microsphere has drawn more and more attention in the past two decades. In order to synthesize it, an efficient procedure was employed by combining dispersion and seeding polymerizations together. The polymerization can be divided into two processes: nucleation and growth. Monodisperse polystyrene seed colloids with a diameter of 2 μm were synthesized in the nucleation process using dispersion polymerization, and then the seed colloids were swollen by monomer and further polymerized in the growth process. Finally, monodisperse polymer microspheres with an average diameter of 10 μm were obtained.

Microwave assisted preparation of monodisperse polymeric microspheres and its morphologies and kinetics

The emulsifier-free emulsion polymerization of N-hydroxymethyl acrylamide (NMA), methyl methacrylate (MMA) and styrene (St) was successfully carried out under microwave irradiation, and monodisperse polymeric microspheres were prepared. The experimental results show that the emulsifier-free emulsion polymerization under microwave irradiation has more rapid reaction rate, higher conversion and shorter induction time than the copolymerization with conventional heating. The apparent activation energies are 61.04 and 83.75 kJ/mol, respectively; the microspheres have spherical morphology, and the microspheres prepared by emulsifier-free emulsion polymerization under microwave irradiation are smaller, more uniform than those obtained with conventional heating.