Microsuspension Polymerization Research Articles

Preparation of magnetic amphiphilic resin microspheres via the one-step polymerization method and extraction of four glucocorticoids for HPLC–MS analysis

Amphiphilic materials can be used for sample preparation of chromatography or mass spectrometry. Amphiphilic materials with magnetic properties in combination with magnetic suction devices allow for automated sample preparation. However, conventional synthesis methods are cumbersome and not suitable for the mass production of the material. In this study, a micro-suspension polymerization method was developed to synthesize magnetic amphiphilic resin microspheres (MARMs), providing new ideas for the preparation of amphiphilic microspheres. MARMs with particle sizes ranging from 3 to 6 μm were successfully prepared, with BET surface area up to 653.2 m2/g. A magnetic solid-phase extraction method based on MARM-5 was developed for the extraction of four glucocorticoids including Cortisone, Hydrocortisone, Cortodoxone, and Corticosterone. This method had a very short adsorption time of 0.5 min and a total extraction time of only 13 min. The limit of detection for the four glucocorticoids ranged from 0.22 to 0.82 ng/L. There was a good linear relationship between sample concentration and peak area in the range of 25∼500 ng/L. Relative recovery of 98 %∼108 % and internal standard normalized matrix effect factors of 95∼114 % were obtained, and the relative standard deviation was between 2.3 % and 6.3 %. The MARMs would be used as excellent solid extraction material for glucocorticoids.

Preparation of bio-based heat storage microcapsules of cellulose acetate butyrate/ polymethylmethacrylate composite by micro-suspension polymerization

ABSTRACT Because of environmental concerns, the utilization of bio-based, renewable resource materials has attracted great attention for a wide range of applications. In this research, green cellulose-based microcapsules containing capric acid (CA) as a bio-heat storage material were prepared. Cellulose acetate butyrate (CAB)/methacrylate polymer composite particles were produced by microsuspension iodine transfer polymerization to encapsulate CA. The influences of methacrylate polymer type and amount on microcapsule morphology, encapsulation efficiency (EE) and thermal properties were investigated. Using methyl methacrylate (MMA) monomer, the colloidal stable spherical microcapsules with smooth surfaces and core-shell morphology were obtained. Although high percentages of EE, ≥70%, were obtained at all CAB:MMA weight ratios, the latent heats of the encapsulated CA were lower than those of the original ones which may be due to the incomplete phase separation of the CAB/PMMA shell and CA core. The increase of CA content up to 60% provided stable spherical microcapsules with a maximum loading of 59% and 97% EE. After thermal cycling for 100 cycles, stable microcapsules still remained with stable thermal properties. The obtained bio-based microcapsules would be well applied for heat storage and temperature control applications.

Microemulsion and microsuspension polymerization of methyl methacrylate in surfactant-free microemulsions (SFME)

HypothesisThis article presents a free-radical polymerization method in a mesostructured system – free of any surfactants, protective colloids, or other auxiliary agents. It is applicable for a large variety of industrially relevant vinylic monomers. The aim of this work is to study the impact of surfactant-free mesostructuring on the polymerization kinetics and the polymer derived. ExperimentsSo-called surfactant-free microemulsions (SFME) were investigated as reaction media with a simple composition comprising water, a hydrotrope (ethanol, n-propanol, isopropanol, tert-butyl alcohol), and the monomer as the reactive oil phase (methyl methacrylate). Polymerization reactions were performed using oil-soluble, thermal- and UV-active initiators (surfactant-free microsuspension polymerization) and water-soluble, redox-active initiators (surfactant-free microemulsion polymerization). Structural analysis of the SFMEs used and the polymerization kinetics were followed by dynamic light scattering (DLS). Dried polymers were analyzed with regard to their conversion yield by mass balance, the corresponding molar masses were determined using gel permeation chromatography (GPC), and the morphology was investigated by light microscopy. FindingsAll alcohols are suitable hydrotropes to form SFMEs, except for ethanol, which forms a molecularly disperse system. We observe significant differences in the polymerization kinetics and the molar masses of the polymers obtained. Ethanol leads to significantly higher molar masses. Within a system, higher concentrations of the other alcohols investigated give rise to less pronounced mesostructuring, lower conversions, and lower average molar masses. It could be demonstrated that the effective concentration of alcohol in the oil-rich pseudophases as well as the repulsive effect of the surfactant-free, alcohol-rich interphases constitute the relevant factors influencing polymerization. Concerning the morphology, the polymers derived range from powder-like polymers in the so-called “pre-Ouzo region” over porous-solid polymers in the bicontinuous region to dense, almost compacted, transparent polymers in unstructured regions, comparable to the findings for surfactant-based systems reported in the literature. Polymerizations in SFME comprise a new intermediate between well-known solution (i.e., molecularly dispersed) and microemulsion respectively microsuspension polymerization processes.

The Novel Polymethacrylate Based Hydrophilic Stationary Phase for Ion Chromatography.

Ion chromatography is widely used as a useful and powerful tool for the analysis of anionic and cationic components found in waters and aqueous media. The performance and selectivity of ion chromatography are based on the stationary phase column packed material. In this study, it is aimed to develop new column material with quaternary ammonium functional group based on monodisperse polymeric particles for ion chromatography and to investigate their chromatographic performance. For the analysis of inorganic anions by ion chromatography, new stationary phases macroporous monodisperse particles based on 3-chloro-2-hydroxy propylmethacrylate-co-ethylene dimethacrylate are obtained as column packing material. 3-chloro-2-hydroxy propylmethacrylate and ethylene glycol dimethacrylate are transformed to porous monodisperse particle form by using glycidyl methacrylate as the seed latex and ethyl benzene as the porogen solvent via micro-suspension polymerization technique. Then macroporous monodisperse particles surface is functionalized by triethylamine so strong anion exchange is obtained for ion chromatography packing material. A series of stationary phases prepared from polymer particles containing different amounts of porogen solvent were tested. The results show that column packing material is successful to separate inorganic anions mixture such as F-, Cl-, NO2-, Br-, NO3- by using the carbonate and bicarbonate solutions as mobile phases.

Synthesis of micrometer-sized poly(vinyl acetate) particles through microsuspension iodine transfer polymerization: effect of iodine species in a water medium

Schematic of the behaviors of iodine species in the microsuspension polymerization of vinyl acetate (VAc) in an aqueous medium.

Synthesis of Micrometer-Sized Poly(methyl acrylate) by Temperature-Step Microsuspension Polymerization with Iodoform Based on the "Radical Exit Depression" Effect§.

Previously, we have reported the successful preparation of micrometer-sized poly(methyl methacrylate) particles without submicrometer-sized byproduct particles by microsuspension iodine-transfer polymerization (ms ITP), in which the radical exit depression (RED) effect was expected, with the benzoyl peroxide initiator at 8 wt % relative to the monomer. However, it was difficult to apply it simply under a similar condition for methyl acrylate (MA), which is more hydrophilic than methyl methacrylate (MMA), because the polymerization rate in the water phase (Rpw) arising from the oligomer radicals exiting from the monomer droplets is high, resulting in a lot of submicrometer-sized byproduct particles. In this study, the problem was overcome by utilizing a two-step temperature process in the microsuspension polymerization with iodoform (ms I) of MA, which supports the proposed mechanism in the ms ITP of MMA in the previous paper. Although the control of the molecular weight (Mn) and the molecular weight distribution (Mn/Mw) was restricted, the preparation of micrometer-sized particles without byproduct particles was realized and a high conversion was reached within a practical time that meets the demands of the industry by utilizing the ms I. The optimal conditions for MA were 70 °C for 2 h, followed by 80 °C for 4 h with a high content of initiator (8 wt % relative to a monomer).

Poly(L-Lactic Acid)-Based Microcapsule Containing Phase-Change Material: Influence of Polymer Shell on Particle Morphology

The preparation of poly(l-lactic acid) (PLLA)-based microcapsules containing phase change material Rubitherm 27 (RT27) by microsuspension polymerization was first developed. Before polymerization, a commercial PLLA was depolymerized via glycolysis to produce a shorter molecular chain as in PLLA glycosates (GPLLA). The influence of the polymer shell on particle morphology was studied by Optical microscope and Scanning electron microscope. The chemical structures of the obtained polymer microcapsule were characterized by Fourier-transform infrared spectroscopy and Nuclear magnetic resonance spectroscopy. The thermal properties and content of encapsulated RT27 were measured by Differential scanning calorimetry and Thermogravimetric analysis. Phase separation was clearly observed after droplet generation with methyl methacrylate, ethylene glycol dimethacrylate, and polyethylene glycol diacrylate as comonomers. After polymerization, broken particles were obtained. In contrast, a spherical microcapsule with a smooth surface was obtained with copolymerization between GPLLA and glycidyl methacrylate. In addition, high encapsulation efficiency (96 %) was obtained. The latent heats of encapsulated RT27 in the term of J/g-RT27 were 202 and 200 J/g-RT27 for the heat of melting and crystallization, respectively, which were close to those of the pristine RT27. Moreover, a supercooling phenomenon was not observed.

Microsuspension Polymerization of Styrene Using Cellulose Nanocrystals as Pickering Emulsifiers: On the Evolution of Latex Particles.

We report a mechanistic study of the microsuspension polymerization of styrene stabilized by cellulose nanocrystals (CNCs) in its native form as well as graft-modified with copolymers of styrene and N-3-(dimethylamino)propyl methacrylamide (DMAPMAm) or N,N-(diethylamino)ethyl methacrylate (DEAEMA). Native CNCs and graft-modified CNCs were shown to form stable styrene emulsions with an average droplet diameter of 18-20 and 5-9 μm, respectively. Initiators of widely varying water solubilities [2,2'-azobisisobutyronitrile (AIBN), 2-2'-azobis(2,4-dimethylvaleronitrile) (Vazo-52), and lauroyl peroxide (LPO)] were employed for the polymerizations. The type of initiator and the type of CNC were shown to directly affect the microsuspension polymerization kinetics, particle size, and molecular weight distribution. Using AIBN and Vazo-52, submicron latex particles were observed in the final latex in addition to the desired 3-20 μm CNC-armored microsuspension particles. The resulting latex and microsuspension polystyrene particles were studied for their CNC coverage and surface charge. We found that the presence of CNCs in the aqueous phase did not lead to Pickering emulsion polymerization by heterogeneous nucleation.

Preparation of rosin-based polymer microspheres as a stationary phase in high-performance liquid chromatography to separate polycyclic aromatic hydrocarbons and alkaloids

AbstractAcrylpimaric acid ethylene glycol acrylate was used as the cross-linking agent to prepare rosin-based polymer microspheres through membrane emulsification–microsuspension polymerization. The prepared microspheres were used as the stationary phase in high-performance liquid chromatography for the separation of polycyclic aromatic hydrocarbons (PAHs) and two analogues of alkaloids. Five PAHs (benzene, naphthalene, fluorene, pyrene, and benzo(e)pyrene) were well separated in the rosin-based polymer column with the resolution (Rs) of 6.088 ± 0.006, 5.759 ± 0.017, 7.019 ± 0.020, and 8.584 ± 0.063. A linear relationship was observed for the carbon numbers of PAHs and lnK as obtained with the equation of ln k = 0.22nc – 2.45, R2 = 0.996 . The rosin-based polymer columns were also employed to separate theophylline–caffeine and camptothecin–10-hydroxy-camptothecin, and the good results were obtained with the Rs of 4.617 ± 0.005 and 2.245 ± 0.049, respectively.

Preparation of high performance copolymer microcapsule encapsulated heat storage material without supercooling

ABSTRACTThe methyl methacrylate (MMA)-based copolymer microcapsules encapsulating Rubitherm®27 (RT27) used as a phase change material were successfully prepared by microsuspension polymerization. The influence of three types of crosslinked comonomers such as ethylene glycol dimethacrylate), trimethylolpropane trimethacrylate, and divinylbenzene (DVB) on the microcapsule formation was studied at various ratios of MMA:crosslinked comonomer. It was found that using MMA:DVB at 70:30 wt% was the optimum ratio. The obtained microcapsules were nonspherical in shape with a dent and high shell strength. In addition, the latent heats of melting and crystallization of the encapsulated RT27 were about 140 J/g-RT27 which were close to those of the original RT27. However, the crystallization temperatures (Tc) of the encapsulated RT27 (14°C) were lower than that of the original RT27 (25°C) which was called supercooling. To prevent supercooling, the effect of nucleating agents (emulgen 150, 1-octadecanol, and RT58) on decreasing supercooling of the encapsulated RT27 was investigated. The results clearly presented that the addition of at least 5 wt% of RT58 significantly increased Tc (25°C) of the encapsulated RT27, whereas the observed latent heats were pretty close to original RT27.

High performance biocompatible cellulose‐based microcapsules encapsulating gallic acid prepared by inverse microsuspension polymerization

AbstractIn this study, the preparation of biocompatible cellulose‐based microcapsules encapsulating gallic acid (GA), an important antioxidant of Bambara groundnut extracts, by water‐in‐oil inverse microsuspension polymerization was studied. GA and carboxymethyl cellulose (CMC) were selected as core and shell materials, respectively. For high encapsulation efficiency, CMC was firstly modified (modified‐CMC (m‐CMC)) with 3‐(trimethoxysilyl)propyl methacrylate (MPS) as a silane coupling agent. It was subsequently polymerized with methacrylic acid (MAA) monomer through a radical route, forming a PMAA grafted m‐CMC (m‐CMC‐g‐PMAA) biocompatible polymer shell. Using CMC:MPS in a ratio of 75:25 (w/w %), highly water‐soluble m‐CMC containing a C=C bond for further radical polymerization was obtained. After inverse microsuspension polymerization at various ratios of m‐CMC:MAA, highly stable spherical m‐CMC‐g‐PMAA microcapsules encapsulating GA were formed in all ratios. It was observed that the encapsulation efficiency increased with increase in MAA content. m‐CMC:MAA in a ratio of 33:67 (w/w%) presented the highest encapsulation efficiency which may due to the increase of hydrophilicity of the aqueous phase. It also presented rapid release and non‐cytotoxic characteristics, suited for use in cosmetic products. © 2018 Society of Chemical Industry

Design of Reversed Phase Chromatography (RPC) Column Packing Material for Protein Separation: Part 1- Synthesis and Characterization

In the first part of the two-part study, the column packed materials in the form of monodisperse and porous particles were synthesized with regard to test their column performances in Reverse Phase Chromatography (RPC). Particles in the form of poly(vinyl acetate-co-divinylbenzene) [poly(VAc-co-DVB)] and poly(divinylbenzene) [poly(DVB)] were produced by “multi-stage micro-suspension polymerization”. The surface of particles were converted to “hydroxyl” form by base hydrolysis that were used as poly(vinylalcohol-co-divinylbenzene) [poly(VA-co-DVB)] particles, having appropriate structural properties like surface and porosity for chromatographic applications. Particle characterization was assessed by Scanning Electron Microscopy (SEM), BET surface area and porosity measurement system and Fourier Transform Infrared Spectroscopy (FTIR).

Cellulose Nanocrystals and Methyl Cellulose as Costabilizers for Nanocomposite Latexes with Double Morphology

Cellulose nanocrystals (CNCs) are sustainable rigid rod-shaped nanoparticles that have potential as reinforcing agents in polymer nanocomposites. CNCs can also act as Pickering stabilizers in emulsions and foams due to their amphiphilic nature. In this work, CNCs were rendered surface active through adsorption with the biopolymer methyl cellulose (MC) to produce MC-coated CNCs. MC-coated CNCs were used to stabilize the microsuspension polymerization of methyl methacrylate. Monomer conversion, latex size, and gel content were studied. The microsuspension polymerization resulted in a double morphology where poly(methyl methacrylate) (PMMA) microparticles and nanoparticles were produced simultaneously. The ratio of micro- to nanoparticles could be tuned based on the CNC:MC ratio. Most nanoparticles were attached to the microparticles offering hierarchically structured latexes, although approximately 2 wt % were free in suspension. Drying conditions could be used to control the surface roughness of the dry la...

Preparation and evaluation of paclitaxel-imprinted polymers with a rosin-based crosslinker as the stationary phase in high-performance liquid chromatography

In this study, molecularly imprinted polymer (MIP) microspheres for paclitaxel (PTX) were prepared by microsuspension polymerization and used as a stationary phase in high-performance liquid chromatography (HPLC) for the separation of PTX and its structural analog docetaxel (DOC). For MIP synthesis, ethylene glycol maleic rosinate acrylate and 2-vinylpyridine were used as the cross-linker and functional monomer, respectively. MIP microspheres were characterized by scanning electron microscopy, laser granulometry, nitrogen sorption porosimetry, and thermogravimetric analysis. Results indicated the formation of regular MIPs with an even pore size distribution; furthermore, these MIPs exhibited excellent thermal stability. These MIP microspheres were packed into a stainless steel column for the selective separation of PTX and DOC. Under optimum chromatographic conditions, a separation factor of 2.54 and an imprinting factor of 2.37 were obtained. In addition, thermodynamic data obtained from van’t Hoff plots revealed enthalpy-driven separation and higher contribution from functional group interactions as compared with that from steric complementary interactions. Microcalorimetry was employed to investigate the binding mechanisms of the analytes on the MIP surface.

Innovative one-step synthesis of hollow polymer particles by microsuspension polymerization of styrene and methyl acrylate with Mg(OH)2 as dispersant

Several methods consisting of two or multi-step processes have been so far proposed for the preparation of sub- and micrometer-sized hollow polymer particles. In this study, we proposed an innovative one-step synthesis of the hollow polymer particles by applying microsuspension copolymerization of styrene and methyl acrylate with Mg(OH)2 as dispersant. In this method, Mg(OH)2 acted not only as dispersant, which covered densely at the surface of the monomer droplets, but also caused hydrolysis reaction of MA unit within styrene-methyl acrylate copolymer particles during the polymerization due to giving alkaline pH in the aqueous medium. It is also important that methyl acrylates are predominantly polymerized over styrene at the initial stage of the microsuspension copolymerization.

Newly designed silver coated-magnetic, monodisperse polymeric microbeads as SERS substrate for low-level detection of amoxicillin

We report the preparation of silver-coated magnetic polymethacrylate core–shell nanoparticles for use in surface-enhanced Raman scattering based drug detection. Monodisperse porous poly (mono-2-(methacryloyloxy)ethyl succinate-co-glycerol dimethacrylate), poly (MMES-co-GDMA) microbeads of ca. 5 μm diameter were first synthesized through a multistage microsuspension polymerization technique to serve as a carboxyl-bearing core region. Microspheres were subsequently magnetized by the co-precipitation of ferric ions, aminated through the surface hydroxyl groups and decorated with Au nanoparticles via electrostatic attraction. An Ag shell was then formed on top of the Au layer through a seed-mediated growth process, resulting in micron-sized monodisperse microbeads that exhibit Raman enhancement effects due to the roughness of the Ag surface layer. The core–shell microspheres were used as a new substrate for the detection of amoxicillin at trace concentrations up to 10−8 M by SERS. The proposed SERS platform can be evaluated as a useful tool for the follow-up amoxicillin pollution and low-level detection of amoxicillin in aqueous media.

Encapsulation of octadecane in poly(divinylbenzene-co-methyl methacrylate) using phase inversion emulsification for droplet generation

Octadecane (OD), a heat storage material, was encapsulated into poly(divinylbenzene-co-methyl methacrylate) or P(DVB-co-MMA) matrix via the microsuspension polymerization. The oil droplets were first generated by using the phase inversion emulsification, i.e., adding a sodium dodecyl sulphate (SDS) aqueous solution into an oil phase (monomers:OD = 1:1) containing various concentrations of poly(vinyl alcohol) (PVA). Results showed that 0.1 wt% of SDS in aqueous medium with the additional rate of 2 mL/min and 3 wt% of PVA in oil phase were the optimal conditions for the formation of nonspherical microcapsules. The smallest number- (dn) and weight- (dw) average diameters of P(DVB-co-MMA)/OD were, respectively, 3.1 and 3.2 µm with a narrow particle size distribution (dw/dn) of 1.02. The latent heats of the encapsulated OD increased with increasing MMA content of microcapsules. The heat of melting (ΔHm; 223 J/g-OD) and crystallization (ΔHc; 230 J/g-OD) of the OD encapsulated in microcapsules using DVB:MMA of 30:70 were higher than those using only PDVB (189 and 193 J g-OD for ΔHm and ΔHc, respectively) and comparable to those of bulk OD (233 and 234 J/g-OD for ΔHm and ΔHc, respectively). The obtained P(DVB-co-MMA)/OD microcapsules would be useful as high performance heat storage material.

Microencapsulation of Ascorbic Acid for Cosmetic by Utilizing Self-assembly of Phase Separated Polymer.

Micrometer-sized polymer particles encapsulated ascorbic acid (vitamin C; VC) were successfully prepared by the three types of the self-assembling method, those are, phase separation and self-assembly of added polymer at the oil-water interface in emulsion, microsuspension polymerization utilizing the self-assembling of phase separated polymer (SaPSeP) method, and their hybrid method. In the stability study at 50°C for 2 months, the three kinds of capsule particles exhibited effective protection of VC from the interaction with other components in cosmetic consisting of water-in-oil (W/O) emulsion. The encapsulated VC was easily released from the capsule particles by an excess of water. These encapsulation methods will be useful for the stabilization of water-soluble substances in cosmetic consisting of W/O emulsion.

Preparation of hybrid composite microspheres containing nanosilicon via microsuspension polymerization

ABSTRACTHybrid composite microspheres with nano‐Si as the core and poly(styrene‐co‐acrylonitrile) as a shell are successfully prepared by a two‐step polymerization technique, which includes dispersion polymerization of styrene and 3‐methacryloxypropyl trimethoxysilane in ethanol for surface modification of nano‐Si followed by microsuspension polymerization of styrene and acrylonitrile in an aqueous phase for encapsulating nano‐Si into an SAN copolymer matrix. The structure and surface properties of modified nano‐Si are investigated by Fourier transform infrared spectroscopy (FTIR) and contact angle. The hybrid composite microspheres are systematically characterized by energy dispersive spectroscopy, thermogravimetric analysis, and transmission electron microscopy (TEM). According to the FTIR spectra and the contact angle experiments, it was determined that a hydrophobic polymer layer was formed on the surface of nano‐Si. TEM showed that nano‐Si was homogeneously dispersed in SAN particles when the loading capacity of nano‐Si in the hybrid composite microspheres was less than 20 wt %. Moreover, scanning electron microscopy and X‐ray photoelectron spectroscopy revealed that there were large amounts of nano‐Si absorbed on the surface of the hybrid composite microspheres, and the mean particle size became much larger when the loading amounts of nano‐Si reached 25 wt %. From this, it can be inferred that nano‐Si overflows from the inner core to the outside surface in the emulsification process and acts as an inorganic dispersant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43101.

Amphiphilic Polymerizable Porphyrins Conjugated to a Polyglycerol Dendron Moiety as Functional Surfactants for Multifunctional Polymer Particles.

An amphiphilic polyglycerol dendron (PGD) conjugated porphyrin (PGP) bearing a polymerizable group was successfully synthesized. The PGP was used as an effective surfactant in emulsion and microsuspension polymerization systems to prepare styrene and methacrylate polymer particles, and the use of PGP provided the simple polymer particles with fluorescence derived from the metalloporphyrin and high colloidal stability due to the PGD. Furthermore, based on confocal laser scanning microscopy, we observed that the particles spontaneously formed a core-shell morphology with the PGP localized in the shell region during the polymerization and demonstrated drug loading in the shell region using rhodamine B as a model drug. The results indicate that the use of the functional surfactant PGP led to the preparation of multifunctional polymer particles from simple monomer species, and the resulting particles possessed high colloidal stability, fluorescence, and drug loading capability.