Functional Polymeric Microspheres Research Articles

Synthesis of poly(maleic anhydride-co-vinyl chloride) crosslinked microspheres and its superior enhancement in mechanical strength and antibacterial activity for poly(vinyl alcohol) composite films

Poly(vinyl alcohol) (PVA) is an attractive raw material and widely applicated in multiple fields owing to its unique features. However, the poor mechanical strength and without intrinsic antimicrobial activity severely restrained its further use. Herein, we proposed a novel strategy to fabricate PVA-based composites film with excellent mechanical properties and superior antibacterial activity by employing functional polymeric microspheres as a hydrogen bonding cross-linker and bactericide loading platform. Firstly, we synthesized poly(maleic anhydride-co-vinyl chloride) cross-linked microspheres (PDVM) via self-stabilized precipitation polymerization and subsequently the PDVM microspheres were reacted with gaseous ammonia to endow the microsphere surface with abundant carboxyl and amidogen group. As a result, uniform PDVM microspheres with diameters ranging from 175 to 685 nm and controlled gel content (25.3–91.8%) were prepared successfully and aminolyzed PDVM microsphere (NPDVM) were obtained. By incorporating 5 wt% NPDVM in PVA matrix, the composite film has a significant increment in tensile strength (63.9 MPa) and elongation at break (107 %) in comparison to neat PVA (51.8 MPa, 80%) mainly attributed to the formation of multiple hydrogen bonding network. Furthermore, by immobilizing Zn2+ on the surface of NPDVM/PVA film via complexation, the composite film exhibited outstanding antibacterial efficiency against E. coli and S. aureus.

Research Progress on Functionalized Polymer Microspheres for Deep Profile Control and Flooding

Research Progress on Functionalized Polymer Microspheres for Deep Profile Control and Flooding

SYNTHESIS AND PROPERTIES OF POLYMER SUSPENSIONS OBTAINED BY HETEROPHASE POLYMERIZATION IN THE PRESENCE OF α,ω BIS[3 GLYCIDOXYPROPYL]POLYDIMETHYLSILOXANE

Polymeric microspheres with glycidoxy groups on the surface can be used as bioligand carriers in diagnostic test systems. However, the possibility of synthesizing aggregatively stable functional polymeric microspheres in a wide range of diameters is an urgent problem of modern polymer chemistry. This article is devoted to a systematic study of the kinetics of styrene and methyl methacrylate polymerization in the presence of an organosiloxane surfactant with terminal glycidoxy groups – α,ω-bis[3-glycidoxyproopyl]-polydimethylsiloxane, PDMS(CHOCH2). The article shows the influence of phases volume ratio, initiator and surfactant concentration, synthesis temperature and pH of initial medium on the properties of polymer suspensions (their aggregative stability, monodispersity, particle diameter). The formation of polymer-monomer particles during polymerization has been studied and it has been shown that polymer suspensions retain high aggregation stability from early period of monomer conversion, and the particle diameter changes untill 30% of the monomer conversion. Due to the high surface activity of the organosiloxane surfactant used and its incompatibility with the resulting polymer, aggregatively stable functional polymer suspensions with diameters from 0.09 to 1.1 μm were obtained by a single-stage synthesis. Studies of the hydration degree of polymer microspheres have shown that the presence of functional glycidoxy groups on their surface ensures the formation of a hydration shell, which increases the stability of polymer particles, and also makes it possible to use the resulting microspheres as carriers of bioligands. Thus, the use of water-insoluble organosiloxane surfactants as stabilizers for the heterophase polymerization of vinyl monomers makes it possible to synthesize aggregatively stable functional polymer suspensions in a wide range of diameters. The use of organosiloxane surfactants with various functional groups expands the range of functional polymer microspheres used in various fields of application.

Characterization and evaluation of functional polymer microspheres with core-shell structure

Characterization and evaluation of functional polymer microspheres with core-shell structure

An improved solvent evaporation method to produce poly (lactic acid) microspheres via foam-transfer

The aim of this work was to study an improved solvent evaporation method to prepare poly (lactic acid) (PLA) microspheres via foam-transfer. Since the foaming process and its transfer were critical to the improved method, they have been studied. Additionally, the delivery capability of foams was studied as a function of the oil/water ratio, the stirring rate, the concentration of polyvinyl alcohol (PVA) and ethanol (EtOH) in the aqueous phase (ωPVA, ωEtOH). It was found that foaming varied during the preparation process and it influenced the properties of PLA microspheres. When the oil/water ratio (w/w) ≥ 3:10, stirring rate ≥ 600 r/min, ωPVA ≥ 1 wt%, and ωEtOH = 0 wt%, solvent evaporation was able to produce enough foams for foam-transfer, which helped to deliver more than 89 wt% PLA microspheres to the receiving vessel. However, ωPVA ≤ 0.3 wt% and ωEtOH = 20 wt% were unfavorable for maintaining the spherical shape of PLA microspheres and caused the aggregation. The methodology was further used to prepare azoxystrobin-loaded PLA microspheres successfully with a high encapsulation efficiency of 86.54%. This work is meaningful since it enables an efficient and continuous route to prepare functional biodegradable polymer microspheres.

Top-down Approach for Fabrication of Polymer Microspheres by Interfacial Engineering

Polymer microspheres with uniform size, composition, and surface property have gained extensive researches in past decades. Conventional bottom-up approaches are using monomers or oligomers to build up desired polymer microspheres. However, directly shaping high-molecular-weight polymers into well-ordered polymer microspheres remains a great challenge. Herein, we reported a facile and efficient top-down approach to fabricate microspheres with high-molecular-weight polymer microfibers. By harnessing interfacial engineering-control during the polymer microspheres formation, uniformly sized microspheres could be produced with widely ranged diameters (from 10 µm to the capillary length of each polymer melt). The size limitation of this approach could be further extended by a controllable Plateau-Rayleigh instability phenomenon. Principally, the top-down approach allows fabrication of microspheres by various polymer melts with surface energy higher than 25 mN/m. Our work paves a way for green, cost-effective, and customizable production of a variety of functional polymer microspheres without any chemical reaction assistant.

Selective Enrichment of Clenbuterol onto Molecularly Imprinted Polymer Microspheres with Tailor-made Structure and Oxygen Functionalities.

The noxious clenbuterol misapplied as the feed additive has posed an enormous threat to humans who actively rely on the food chains with high potential of contamination by clenbuterol, such as pork and beef. It is, therefore, highly desirable to develop novel materials and strategies for dealing with the clenbuterol. Herein, functional polymer microspheres prepared by Pickering emulsion polymerization were explored for the selective enrichment of the clenbuterol, and their structure and oxygen functionalities could be tailor-made by a molecular imprinting process. The clenbuterol imprinting was adequately demonstrated to not only increase the particle size (~52 nm vs. ~42 nm) and create cavities for the accommodation of the clenbuterol molecules, but also reduce the oxygen functionalities of the resulting molecularly imprinted polymer microspheres (MIPMs) by approximately 4 at.%, which is believed to correlate with the high specificity of the MIPMs. Various characterization methods were employed to evidence these findings, including scanning electron microscopy, BET measurements, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental mapping examination. More importantly, the MIPMs showed a markedly superior enrichment capability towards clenbuterol to the counterpart, that is, non-molecularly imprinted polymer microspheres (NIPMs). Compared to the NIPMs without specificity for clenbuterol, the MIPMs exhibited an impressive selectivity to clenbuterol, with the relative selectivity coefficient (k′) values largely exceeding 1, thus corroborating that the useful molecular imprinting led to the generation of the binding sites complementary to the clenbuterol molecule in the size and functionalities. The MIPMs were also employed as the stationary phase to fabricate molecularly imprinting solid-phase extraction column, and the spike recovery was demonstrated to be not significantly decreased even after nine cycles. Furthermore, the reliability of the method was also evidenced through the comparison of the MIPMs prepared from different batches.

Preparation of double-emulsion-templated microspheres with controllable porous structures by premix membrane emulsification

A scalable and versatile strategy was developed for the fabrication of uniform polymeric microspheres with controllable interconnected porous structures. Uniform water-in-oil-in-water emulsions with linear poly(methyl methacrylate–glycidyl methacrylate) in the oil phase were generated by two-step premix membrane emulsification and used for constructing the microspheres. During the emulsion solidification process, internal water droplets were packed densely together, forming a thin oil film between the internal and external water phases. After solvent diffusion, the thin film can be ruptured and pores can be templated from the internal water droplets to form interconnected porous structures. Membranes with various pore sizes were obtained. The osmotic pressure and Laplace pressure balance were used to control the porosity and pore size precisely. The proposed method enables the fabrication of functional polymeric microspheres with uniform and controllable porous structures and particle sizes. This improves their performance and broadens the scope of their applications, especially in chromatographic separation.

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.

Functional polymer microspheres as “turn-off” chemosensors for detection of copper cations

Functional polymer microspheres with fluorescent carbazole unit and various functional groups, such as amide, pyridyl, and imidazole, were prepared by distillation precipitation copolymerization of divinylbenzene (DVB) as a crosslinker, N-vinylcarbazole (NVCz), together with acrylamide (AAm), 4-vinylpyridine (VPy), and 1-vinylimidazole ((VIM) as functional monomers in acetonitrile in the absence of any stabilizer. The resultant polymer microspheres were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, photoluminescent spectroscopy, inductively coupled plasma (ICP), and X-ray photoelectron microscopy (XPS). The functional polymer microspheres acted as a “turn-off” chemical sensor with excellent stability for determination of copper cation (Cu2+) in methanol via the quenching effect of fluorescence after adsorption of Cu2+ from the solution through the capture ability of functional groups, such as pyridyl, imidazole, and amide on the surface of polymer microspheres. A good linear relationship was set up between the photoluminescence intensity at the emission peak of 352 nm and the Cu2+ concentrations ranging from 0 to 1.0 μM with the presence of pyridyl group as a ligand. The effects of the functional groups were investigated on the fluorescent response for the microspheres as chemical sensors.

Molecular synergistic strategy to fabricate bilirubin medical adsorbent material for hyperbilirubinemia hemoperfusion

ABSTRACTNeonatal hyperbilirubinemia (jaundice) is a common disease with high incidence. Currently, hemoperfusion (blood exchange transfusion) is always used for the treatment of severe hyperbilirubinemia. However, there are several limitations of blood exchange transfusion, such as the lack of a safe blood supply and blood transfusion complications, while the main problem of hemoperfusions is the inefficient performance of current bilirubin absorbent, which makes it impossible to administer to the neonatal hyperbilirubinemia cases. Identification of a bilirubin hemoperfusion adsorbent with overall excellent performance is the most crucial key to solving the above clinical problems. In this work, a novel bilirubin adsorbent was customized based on molecular design strategy, namely, functional polymeric microspheres were first fabricated by the copolymerization of glycidyl methacrylate with other monomers, and then modified with an amine component, followed by linking with a functional spacer molecule, and finally immobilized with a functional ligand (albumin). Its chemical and physical properties were characterized; its adsorption performances for bilirubin were investigated under clinical conditions; its medical safety were evaluated by hemolysis test, thrombotest, and platelet adhesion test. The results showed that the adsorbent had good adsorption performance for bilirubin compared to a popular commercial clinical bilirubin hemoperfusion column; and it also had excellent medical safety evaluations. This study sheds a new light on how to develop hemoperfusion bilirubin adsorbents with overall good clinical performance as well as a reference for later studies on this topic.

Well-defined polymer microspheres formed by living dispersion polymerization: precisely functionalized crosslinked polymer microspheres from monomers possessing cumulated double bonds

The precise method for synthesizing well-defined polymer microspheres via π-allylnickel-catalyzed living coordination polymerization of allene derivatives under dispersion polymerization conditions is described. The π-allylnickel-catalyzed living coordination polymerization of allene derivatives such as phenoxyallene was carried out in protic solvents such as methanol in the presence of stabilizers such as polyvinylpyrrolidone to produce polymer microspheres with a narrowly dispersed diameter distribution (Dw/Dn) at a high yield. For example, polymer microspheres with a number-average diameter (Dn) of 1.10 μm and Dw/Dn of 1.01 were obtained at a yield of 97%; these microspheres are composed of a polymer with a controlled molecular weight (Mn=11 700) and narrow molecular weight distribution (Mw/Mn=1.06). The size of the resulting polymer microspheres proved to be affected by polymerization conditions such as the initial monomer concentrations, monomer structures, polymerization media and stabilizers. Unlike conventional dispersion polymerization systems, the use of a bifunctional monomer, 1,4-diallenoxybenzene, for this living dispersion polymerization successfully produced well-defined crosslinked living polymer microspheres that exhibited high solvent tolerance. The postpolymerization of functional allene monomers in the living dispersion polymerization was also successful, resulting in functionalized polymer microspheres that could be applied in solid-phase organic synthesis and solid-supported transition metal catalysis. A controllable process for producing uniform, robust microspheres can make mixed solid-liquid chemical reactions easier to perform. Tiny beads of polymers such as polystyrene are finding increasing use as supports for catalysts in organic synthesis. Now, Ikuyoshi Tomita from the Tokyo Institute of Technology and co-workers have used a ‘living’ coordination mechanism, which polymerizes molecules until directed to stop, to improve the size distribution and modification capabilities of microspheres. Nickel-based catalysts and unsaturated, bifunctional carbon reagents worked together to generate microspheres with cross-linked internal structures for additional strength and solvent tolerance. Furthermore, the microsphere surfaces contained living, growing ends that can attach to additional reagents. Synthetic trials revealed that decorating the microspheres with palladium produced a heterogeneous catalyst that could be recovered and reused multiple times with little loss of activity. The precision synthetic method of well-defined polymer microspheres by the π-allylnickel-catalyzed living coordination polymerization of allene derivatives under the dispersion polymerization conditions is described. Unlike the conventional dispersion polymerization systems, the use of a bifunctional monomer, 1,4-diallenoxybenzene, to this living dispersion polymerization successfully gave well-defined crosslinked living polymer microspheres that exhibit high solvent-tolerant properties. The postpolymerization of functional allene monomers in the living dispersion polymerization also proceeded smoothly to give functionalized polymer microspheres that enabled their applications to the solid-phase organic synthesis and the solid-supported transition metal catalysts.

On-demand one-step synthesis of monodisperse functional polymeric microspheres with droplet microfluidics.

A simple and robust method for one-step synthesis of monodisperse functional polymeric microspheres was established by generation of reversed microemulsion droplets in aqueous phase inside microfluidic chips and controlled evaporation of the organic solvent. Using this method, water-soluble nanomaterials can be easily encapsulated into biodegradable Poly(D,L-lactic-co-glycolic acid) (PLGA) to form functional microspheres. By controlling the flow rate of microemulsion phase, PLGA polymeric microspheres with narrow size distribution and diameters in the range of ∼50-100 μm were obtained. As a demonstration of the versatility of the approach, high-quality fluorescent CdTe:Zn(2+) quantum dots (QDs) of various emission spectra, superparamagnetic Fe3O4 nanoparticles, and water-soluble carbon nanotubes (CNTs) were used to synthesize fluorescent PLGA@QDs, magnetic PLGA@Fe3O4, and PLGA@CNTs polymeric microspheres, respectively. In order to show specific applications, the PLGA@Fe3O4 were modified with polydopamine (PDA), and then the silver nanoparticles grew on the surfaces of the PLGA@Fe3O4@PDA polymeric microspheres by reducting the Ag(+) to Ag(0). The as-prepared PLGA@Fe3O4@PDA-Ag microspheres showed a highly efficient catalytic reduction of the 4-nitrophenol, a highly toxic substance. The monodisperse uniform functional PLGA polymeric microspheres can potentially be critically important for multiple biomedical applications.

Spherical and polygonal shape of Au nanoparticles coated functionalized polymer microspheres

Uniform polystyrene (PS)/polypyrrole (PPy) composite microspheres with well-defined core/shell structures are synthesized by chemical oxidative polymerization. Gold nanoparticles (Au NPs) are successfully coated on the surface of PS/PPy microspheres by means of electrostatic interactions due to the functionalized PPy coatings supplying sufficient amino groups and the additive of mercapto acetic acid. Furthermore, the as-prepared PS/PPy/Au microspheres serving as seeds facilitate Au NPs further growth by in situ reduction in HAuCl4 solution to obtain PS/PPy/Au spheres with the core/shell/shell structure. Morphology observation demonstrates that the monodisperse PS/PPy/Au microspheres compose of uniform cores and the compact coatings containing distinct two layers. X-ray diffraction and X-ray photoelectron spectroscope confirm the existence of PPy and Au on the surface of the composite spheres. This facile approach to preparing metal-coated polymer spheres supplies the potential applications in biosensors, electronics and medical diagnosis.

Renewable Eugenol-Based Polymeric Oil-Absorbent Microspheres: Preparation and Oil Absorption Ability

This article reports a novel type of polymeric microspheres derived from a renewable biomass, eugenol, via a facile and effective suspension polymerization approach. On the basis of eugenol and methacryloyl chloride, we first synthesized and then structurally identified the monomer eugenyl methacrylate (E-MA). By using E-MA as the sole monomer and simultaneously as the cross-linking agent, we successfully prepared cross-linked polymeric microspheres through suspension polymerization in aqueous media with 2,2-azoisobutyronitrile (AIBN) as the initiator and poly(vinyl alcohol) (PVA) as the stabilizer. The resulting microspheres were obtained in high yield with diameters ranging 500–800 μm and exhibited remarkably large oil absorbency in a relatively high speed. The microspheres can be reused for at least five times with little change in maximum absorption. The preparative strategy for the polymeric microspheres can be taken as a versatile platform for preparing more functional polymeric microspheres, which are expected to find significant applications in environmental protection and other fields.

Preparation and Characterization of Platinum and Rhodium Nanoparticles Stabilized by Functional Polymer Microspheres

Preparation and Characterization of Platinum and Rhodium Nanoparticles Stabilized by Functional Polymer Microspheres

Poly(vinylphosphonate)s functionalized polymer microspheres via rare earth metal-mediated group transfer polymerization

We demonstrate a facile, yet efficient method for the functionalization of crosslinked polystyrene (PS) microspheres with biocompatible poly(vinylphosphonate)s via the combination of a UV grafting polymerization and a surface-initiated group transfer polymerization. Self-initiated photografting and photopolymerization of ethylene glycol dimethacrylate results in direct photografting of poly(ethylene glycol dimethacrylate) on the PS microspheres with dangling methacrylate functionalities, which are used to immobilize ytterbocene complexes to form the surface-bound rare-earth metal catalyst system. The surface-initiated GTP of dialkyl vinylphosphonates from the initiator system leads to the functionalization of PS microspheres with poly(vinylphosphonate) brushes. Polymerization kinetic investigation indicates that surface-initiated GTP leads to a constant and remarkably rapid weight gain of the microsphere (a microsphere weight increase of 600% within 3 min), owing to the highly living and efficient character of GTP. The surface-initiated GTP occurring inside the microsphere causes an accumulation of the tension between the polymer chains in the microsphere, which eventually induces fracture of the microsphere for longer polymerization time. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2919–2925

Photochemical Design of Functional Fluorescent Single-Chain Nanoparticles

We report the facile ambient temperature generation of size tunable and well-defined (pro)fluorescent single-chain nanoparticles (SCNPs) via the photoinduced nitrile imine intramolecular cross-ligation of linear precursor polymers, constituting a platform technology as novel imaging agents. A set of three linear precursor polymers (Mn ≈ 14000 g mol-1, Đ ≈ 1.25) was synthesized via nitroxide-mediated statistical copolymerization of styrene and 4-(chloromethyl)styrene (CMS), followed by a postpolymerization modification of the resulting copolymer installing protected maleimide (PG-Mal) as well as tetrazole (Tet) moieties. The tetrazole content (% Tet) along the lateral polymer chains was varied between 12 and 24% in order to preselect not only the size of the corresponding SCNPs, but also their fluorescence and reactive properties. Finally, the applicability of the profluorescent SCNPs for fluorescence labeling was demonstrated utilizing residual surface expressed Tet moieties on the SCNPs surface in a reaction with maleimide functional polymeric microspheres. The (pro)fluorescent single-chain nanoparticles were in-depth characterized by 1H NMR spectroscopy, dynamic light scattering (DLS), size exclusion chromatography (SEC), and atomic force microscopy (AFM), as well as UV/vis and fluorescence spectroscopy.

Application of functional microsphere in human hepatitis B virus surface antigen detection.

A novel and simple emulsifier-free emulsion polymerization technique was developed for preparation of mono-dispersed amino functionalized polymer microspheres with well defined diameters (about 400 nm). Various characterization methods demonstrated that the obtained amino microspheres had a uniform size and good dispersity which were confirmed by scanning electron microscope (SEM). Zeta potential and Fourier transform infrared spectrometer (FT-IR) demonstrated that amino groups have been successfully introduced to the microsphere surface. These functionalized microspheres have been shown to be efficient and controllable carriers capable of immobilizing and enriching monoclonal antibodies. Moreover, a newest chemiluminescent enzyme-linked immunoassay (ELISA) approach has been developed for human Hepatitis B virus surface antigen (HBsAg) detection. HBsAg was sandwiched between goat anti-HBsAg polyclonal antibody and mouse anti-HBsAg antibody. Alkaline phosphatase (ALP) conjugated horse anti-mouse immunnogloblin was used to bond with monoclonal antibody. Finally, chemiluminesent (CL) signals were recorded after adding 3-(2-spiroadamantane)-4-methoxy-4-(3-phosphoryloxy) phenyl-1,2-dioxetane (AMPPD) which was used as a chemiluminescent substrate reagent of ALP. This novel chemiluminescent ELISA assay was proved to be of excellent specificity and high sensitivity when using ALP and AMPPD luminescence systems for specific HBsAg detection.

Efficient synthesis of monodisperse, highly crosslinked, and “living” functional polymer microspheres by the ambient temperature iniferter‐induced “living” radical precipitation polymerization

AbstractThe facile and efficient one‐pot synthesis of monodisperse, highly crosslinked, and “living” functional copolymer microspheres by the ambient temperature iniferter‐induced “living” radical precipitation polymerization (ILRPP) is described for the first time. The simple introduction of iniferter‐induced “living” radical polymerization (ILRP) mechanism into precipitation polymerization system, together with the use of ethanol solvent, allows the direct generation of such uniform functional copolymer microspheres. The polymerization parameters (including monomer loading, iniferter concentration, molar ratio of crosslinker to monovinyl comonomer, and polymerization time and scale) showed much influence on the morphologies of the resulting copolymer microspheres, thus permitting the convenient tailoring of the particle sizes by easily tuning the reaction conditions. In particular, monodisperse poly(4‐vinylpyridine‐co‐ethylene glycol dimethacrylate) microspheres were prepared by the ambient temperature ILRPP even at a high monomer loading of 18 vol %. The general applicability of the ambient temperature ILRPP was confirmed by the preparation of uniform copolymer microspheres with incorporated glycidyl methacrylate. Moreover, the “livingness” of the resulting polymer microspheres was verified by their direct grafting of hydrophilic polymer brushes via surface‐initiated ILRP. Furthermore, a “grafting from” particle growth mechanism was proposed for ILRPP, which is considerably different from the “grafting to” particle growth mechanism in the traditional precipitation polymerization. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013