Suspension Polymerization Reactions Research Articles

TiO2/Polystyrene Nanocomposite Antibacterial Material as a Hemoperfusion Adsorbent for Efficient Bilirubin Removal and Prevention of Bacterial Infection.

The use of hemoperfusion adsorbents for the removal of bilirubin in patients with liver failure has become a critical treatment. However, the insufficient clearance of bilirubin and the possibility of bacterial infection during hemoperfusion limit the application. In this work, we designed a novel antibacterial bilirubin adsorbent (PSVT) through the suspension polymerization reaction between double-bond functionalized TiO2 nanoparticles and styrene. PSVT showed an excellent bilirubin adsorption ability and antibacterial performance, ensuring efficient clearance of bilirubin in liver failure patients during hemoperfusion and preventing bacterial infection. The experimental results indicated that TiO2 was uniformly dispersed in the microspheres, which improved the mesoporous structure and increased the specific surface area. Composite adsorbent PSVT showed an exceptional bilirubin adsorption capacity, with the maximum adsorption capacity reaching 24.3 mg/g. In addition, the introduction of TiO2 endowed PSVT with excellent antibacterial ability; the ultimate antibacterial rates against Escherichia coli and Staphylococcus aureus reached 97.31 and 96.47%, respectively. In summary, PSVT served as a novel antibacterial bilirubin adsorbent with excellent bilirubin clearance capacity and antibacterial performance, providing excellent application prospects for treating liver failure patients.

Preparation of spherical phenol‐formaldehyde beads from phenol‐liquefied wood and the characteristics of carbonized materials

AbstractIn this study, wood of Cryptomeria japonica D. Don (Japanese fir) was liquefied with phenol as a solvent. Phenol‐liquefied wood was mixed with formalin and spherical phenol‐formaldehyde resin (PF) beads were prepared by a two‐stage suspension polymerization reaction. The influence of the kind and dosage of polyvinyl alcohol (PVA) on the particle size distribution, mechanical strength and thermal properties of spherical PF beads were investigated. The results show that PF beads prepared with partially saponified PVA as a granulating agent are smaller than 75 μm, while the PF beads prepared with fully saponified PVA have larger diameters. However, the average diameter of spherical PF beads decreased with the increase of PVA addition. Thermogravimetric analysis (TGA) indicates that the initial thermal degradation temperature of the PF beads is around 150°C, and the main weight loss occurs between 400 and 600°C. Among them, the PF beads with BF‐04 as the granulating agent have the best heat resistance, and have the highest char yield at 800°C. The Brunauer, Emmett and Teller surface adsorption shows that the internal structure of the carbonized spherical PF beads is microporous pores. Carbonized beads prepared with high PVA adding have large absorption volume.

OBTAINING SEMICONDUCTOR CdS, CdSe AND CdSe/ZnS CORE/SHELL NANOPARTICLES AND THEIR COMPOSITES WITH POLYMERS

In this work, high-performance CdS, CdSe and CdSe/ZnS nanocrystals with good luminescence were colloidally synthesized at high temperature and incorporated into micrometer-sized polymethylmethacrylate (PMMA) spheres formed by suspension polymerization reaction. CdS, CdSe and CdSe/ZnS quantum dots obtained by the colloid method were stabilized with oleic acid and their optical properties were studied. It was observed that the intensity peaks of quantum dots did not change after modification to PMMA polymer.

OBTAINING SEMICONDUCTOR CdS, CdSe AND CdSe/ZnS CORE/SHELL NANOPARTICLES AND THEIR COMPOSITES WITH POLYMERS

In this work, high-performance CdS, CdSe and CdSe/ZnS nanocrystals with good luminescence were colloidally synthesized at high temperature and incorporated into micrometer-sized polymethylmethacrylate (PMMA) spheres formed by suspension polymerization reaction. CdS, CdSe and CdSe/ZnS quantum dots obtained by the colloid method were stabilized with oleic acid and their optical properties were studied. It was observed that the intensity peaks of quantum dots did not change after modification to PMMA polymer.

Acrylate-functionalized hyper-cross-linked polymers: Effect of the porogens in the polymerization on their porosity and adsorption from aqueous solution

The porogens are the key components in the polymerization process, they do not participate in the polymerization reaction, but play a very important role in the pore structure of the synthetic polymers. Herein, o-xylene and paraffin were applied as the porogens and three acrylate-functionalized hyper-cross-linked polymers were fabricated according to the suspension polymerization and Friedel-Crafts reaction. The Brunauer-Emmett-Teller (BET) surface area (SBET) and pore volume (Vtotal) of the initial copolymers were nearly zero, while the Friedel-Crafts reaction resulted in a steep increase of the SBET and Vtotal. In particular, the resultant polymer, namely, HCP-PDVE-(Xy), using o-xylene as the porogen had the greatest SBET and Vtotal (1126 m2/g and 0.958 cm3/g, respectively), while the SBET and Vtotal of HCP-PDVE-(Lp) using paraffin as the porogen were the lowest (487 m2/g and 0.299 cm3/g, respectively). Meanwhile, HCP-PDVE-(Xy + Lp) using 50 % of o-xylene and 50 % of paraffin as the mixed porogens possessed the intermediate data. More importantly, HCP-PDVE-(Xy) had the hierarchical micro- and meso-porous distribution, while predominant micro-pores were distributed for HCP-PDVE-(Lp) and HCP-PDVE-(Xy + Lp). The equilibrium adsorption indicated that HCP-PDVE-(Xy + Lp) exhibited the largest equilibrium capacity (qe) to phenol while HCP-PDVE-(Xy) owned the largest qe to Rhodamine B. The phenol adsorption was subjected to the micro-pore filling mechanism while the high SBET, Vtotal and the hierarchical micro-/meso-pores were favorable for the adsorption of Rhodamine B. The kinetic adsorption revealed that HCP-PDVE-(Lp) and HCP-PDVE-(Xy + Lp) (20 min) required much less time than HCP-PDVE-(Xy) (50 min) to reach the equilibrium for the phenol adsorption, and the micro-pore diffusion model characterized the kinetic data very well. The dynamic adsorption indicated that the dynamic capacity of phenol adsorbed on HCP-PDVE-(Xy + Lp) was 160.2 mg/g, very close to the qe (163.6 mg/g) in the equilibrium adsorption.

Synthesis and application of temperature‐sensitive polymer as a novel plugging agent for water‐based drilling fluids

AbstractIn the process of drilling with water‐based drilling fluid, polymer plugging agent is very important to solve the problem of wellbore instability in the formation with micropores and microfractures. In this study, N‐isopropyl acrylamide and 2‐acrylamide‐2‐methylpropanesulfonic acid were grafted onto the surface of SiO2 modified by vinyl trimethoxysilane by reverse suspension polymerization reaction, and a heat‐sensitive polymer plugging agent was synthesized. The structure analysis showed that the synthetic material was the target product, with a particle size of 49.665 μm, high‐temperature resistance and sensitive temperature response behavior. According to laboratory evaluation experiments, it can be seen that the addition of the polymer increased the electrostatic stability of bentonite particles and had a chemical inhibition effect. Under the action of temperature and pressure, the synthesized temperature sensitive plugging agent formed a dense hydrophobic membrane on the surface of mud cake, which physically sealed the microcracks and pores, and reduced the filtration loss, so as to greatly improve the stability of shale. The experimental results showed that the synthesized temperature sensitive plugging agent has excellent high‐temperature resistance and plugging performance.

Liquid-Crystalline Polymer Particles Prepared by Classical Polymerization Techniques.

Liquid‐crystalline polymer particles prepared by classical polymerization techniques are receiving increased attention as promising candidates for use in a variety of applications including micro‐actuators, structurally colored objects, and absorbents. These particles have anisotropic molecular order and liquid‐crystalline phases that distinguish them from conventional polymer particles. In this minireview, the preparation of liquid‐crystalline polymer particles from classical suspension, (mini‐)emulsion, dispersion, and precipitation polymerization reactions are discussed. The particle sizes, molecular orientations, and liquid‐crystalline phases produced by each technique are summarized and compared. We conclude with a discussion of the challenges and prospects of the preparation of liquid‐crystalline polymer particles by classical polymerization techniques.

Use of Bacterial Nanocellulose for Pickering Stabilization of Methyl Methacrylate Suspension Polymerizations

AbstractNanocellulose is a promising material for pickering stabilization of liquid‐liquid and solid‐liquid dispersions because it is a natural and sustainable material that can present surface activity. For this reason, the present work investigates the stability of aqueous dispersions of methyl methacrylate (MMA) prepared in presence of bacterial nanocellulose (BNC) and the use of BNC as suspending agent in free‐radical MMA suspension polymerization reactions. The dispersion stability is evaluated through sedimentation and phase separation analyses, using empirical statistical models to characterize the main effects of operation variables on the preparation of aqueous MMA dispersions. Then, suspension polymerization reactions are carried out at different conditions to characterize the stabilizing performances of the analyzed BNCs during actual reaction trials. Particularly, it is shown that modification of both the BNC concentration and the emulsification conditions can affect the final stability of the obtained emulsions. Additionally, it is shown that PMMA microparticles with diameters ranging from 300 to 1500 µm can be synthesized using BNC as stabilizer and AIBN as initiator, enhancing the sustainable characteristics of the analyzed processes.

Evaluation of Process Variables on the Suspension Polymerization of Vinyl Pivalate

Poly(vinyl pivalate) − PVPi is a poly(vinyl ester) that presents interesting characteristics that lead to the production of embolic agents, such as poly(vinyl alcohol) (PVA), with high level of sindiotacticity in contrast to the one synthesized from poly(vinyl acetate), for example. This work aims the study of the influence of process variables, such as stirring speed, amount of initiator, and suspending agent concentration on the suspension polymerization reaction of vinyl pivalate. Also, it has the objective of studying the way these parameters can influence the properties of the polymeric particles formation. For this purpose, the reaction system was evaluated using 550, 750, 950, and 1150 rpm as stirring speed, fraction of initiator in the range from 0.3 to 0.5 wt.%, and 0.5, 1.0, 1.5, 2.0, and 2.5 g L−1 of suspending agent. All samples were characterized by classical gravimetric measurements, proton nuclear magnetic resonance (1H‐NMR), gel permeation chromatography (GPC), and scanning electron microscopy (SEM). 1H‐NMR measurements confirmed the synthesis of poly(vinyl pivalate). SEM images have suggested the formation of particles with spherical morphology, exhibiting average diameters of 200, 122, 86, and 79 µm related to the stirring speed of 550, 750, 950 e 1150 rpm, respectively. It was also observed that the polymers had average molar mass of 6.7 · 105, 4.8 · 105, and 4.4 · 105 g mol−1 when 0.3, 0.4, and 0.5 wt.% of benzoyl peroxide (BPO) was employed, respectively. The global conversion achieved was ca. 90% in all conditions.

CO2 capture by nitrogen-doped porous carbons derived from nitrogen-containing hyper-cross-linked polymers

The N-containing hyper-cross-linked polymers with different porosity and polarity were prepared from 4-vinylbenzyl chloride and 4-vinyl pyridine by the suspension polymerization and Friedel-Crafts reaction. A carbonization process by KOH chemical activation was carried out for the N-containing hyper-cross-linked polymers, and hence a series of N-doped porous carbons (NDPC) was easily fabricated. These porous materials were comparatively evaluated for CO2 adsorption. The NDPC were much more efficient than the N-containing hyper-cross-linked polymers for the CO2 capture and the CO2 uptake had a linear correlation to the ultramicropore volume (d ≤ 0.8 nm) with R2 = 0.9737. NDPC-10% possessed the highest CO2 uptake around 270 mg/g, and had the sufficient CO2/N2 selectivity of 20.2 at 273 K and 1.0 bar. The CO2/N2 selectivity of the N-containing hyper-cross-linked polymers was much higher than the NDPC due to the higher nitrogen content. The isosteric heat of adsorption on the N-containing hyper-cross-linked polymers ranged 29.0–41.2 kJ/mol while that on the NDPC was much lower (24.6–29.2 kJ/mol). The NDPC developed in this study may provide promising candidates for the CO2 capture.

Novel magnetic carboxyl modified hypercrosslinked resins for effective removal of typical PPCPs

A series of novel magnetic carboxyl modified hypercrosslinked resins were successfully prepared via a sequence of suspension polymerization, hydrolysis and post-crosslinking reactions. The serial resins possessed both high cation exchange capacity and high specific surface area with MA-10 having the supreme specific surface area of 1238.65 m2/g and MA-70 having the largest exchange capacity of 6.45 mmol/g. The serial resins exhibited excellent adsorption capacity of typical PPCPs including chloramphenicol, atenolol, ibuprofen and tetracycline, which were neutral, cationic, anionic and zwitterionic respectively in natural water. The adsorption of chloramphenicol and ibuprofen was dominated by the hydrophobic and π–π Electron-Donor-Acceptor (EDA) interactions, while as to atenolol, the electrostatic interaction dominated the adsorption process. Especially, MA-50 was found to have the largest adsorption amount and the longest equilibrium time of zwitterionic tetracycline compared with other resins, the mechanism of which needed further investigation. Breakthrough tests showed that the serial resins had significant advantages over granular activated carbon F400D in contaminants removal for all of the four target pharmaceuticals. Batch experiments proved that the serial resins possessed strong anti-pollution ability and excellent regeneration property, which made it possible for the practical application in future water treatment.

Tunable synthesis of the polar modified hyper-cross-linked resins and application to the adsorption

The polar modified hyper-cross-linked resins were synthesized by the suspension polymerization and Friedel-Crafts alkylation reaction, and the effect of the feeding amount of the monomers (N-vinylimidazole and p-vinylbenzyl chloride) on the porosity and polarity were clarified. As the feeding amount of p-vinylbenzyl chloride decreased from 75% to 50% (w/w), the Brunauer-Emmett-Teller surface area of the resins lowered from 1306 to 436 m2/g, and the pore size distribution showed a large population of pores in micropores stretching to a higher percentage of mesopores. As the feeding amount of N-vinylimidazole increased from 5% to 30% (w/w), the nitrogen content of the resins rose from 0.005% to 3.06% (w/w), and the contact angle decreased from 97±4.2° to 28±2.0°. As a result, the porosity and polarity of the resins could be accurately tuned by adjusting the feeding amount of the monomers, and the different porosity and polarity of these resins endowed them with selective adsorption to benzoic acid and Rhodamine B.

Novel acrylic/nanocellulose microsphere with improved adhesive properties

A synthesis of acrylic microsphere pressure sensitive adhesives with addition of nanocellulose filler is presented. In the first stage α cellulose was modified by acid hydrolysis and the produced nanocellulose suspension was added into the continuous phase of a suspension polymerization reaction mixture. The amount of nanocellulose varied in range from 0wt% (reference synthesis) to 5wt% calculated on monomer amount. The first part of the study was assigned to the characterization of the synthesized adhesive suspension. Particle sizes and particle size distributions were measured. Then, adhesives were coated via a transfer coating process and adhesive properties were evaluated. Additionally, polymer glass transition temperatures were determined and due to significant differences in measured adhesive properties, adhesive viscoelastic properties were examined using dynamic mechanical analysis (DMA). Results showed that it's possible to use nanocellulose as a nanofiller in microsphere adhesives. Suspensions were stable, mean particle sizes decreased with increasing nanocellulose content mainly due to a higher continuous phase viscosity. Adhesive properties testing revealed non typical behavior for the nanocomposite microsphere PSA material. All three measured adhesive properties increased with increasing nanocellulose content. A synergistic effect of lower particle sizes along with hydrogen bonding exhibited an increase in adhesive properties. DMA analysis showed that the storage modulus (G') increased with increasing amount of added nanocellulose. At the same time a decrease in maximal tan δ values was observed which concurred with improved cohesivity, hence higher shear strength.

Experimental and CFD Study of a Vertically Stirred Tubular Reactor Designed for Suspension Polymerization Reactions

A vertically stirred tubular reactor is designed and studied in this work to perform the styrene batch suspension polymerization. Computational fluid dynamic techniques are applied to acquire information regarding the heat transfer and fluid flow behavior along the reactor. The simulated findings are used to support the experimental results (particle size distribution—PSD) obtained by varying the stirring system configuration, stabilizing agent concentration, and system holdup (styrene/water ratio v/v). According to the results, an efficient temperature control is attained due to the tubular geometry of the equipment. In addition, the PSD broadens by increasing the size of the shaft and the number of impellers installed along the reactor. An evaluation of the particle sedimentation throughout the reaction demonstrates that the PSD and the stirring rate play an important role in the sedimentation kinetics. Such findings demonstrate the potential of the proposed reactor to be explored in order to perform suspension polymerizations semicontinuously or continuously by applying suitable operation strategies. image

Structure and activity of TiO2/FeO co-doped carbon spheres for adsorptive-photocatalytic performance of complete toluene removal from aquatic environment

TiO2 and TiO2-FeO co-doped carbon spheres (CB) synthesized with a suspension polymerization process, followed by carbonization and activation, were used to promote the sorption and photocatalytic removal of toluene from aqueous media. The TiO2 nanoparticles (NPs) and Fe doped TiO2 NPs were incorporated during the middle stage of the suspension polymerization reaction. A porous surface texture on the doped CB was developed by a carbonization and activation process at 800°C under N2 and CO2 atmospheres, respectively. The doped TiO2-FeO NPs acted as visible-light sensitizers for photo-degradation of toluene under visible light irradiation. The maximum removal capacity of toluene (5–100mg/L of aqueous solution) was found to be 48.3, 78.1 and 103.1mg/g, for the TiO2, CB-TiO2 and CB-TiO2-FeO, respectively. The great adsorptive-photo-catalytic process for complete removal of toluene with CB-TiO2-FeO was 98.2%. However, reduction of total organic carbon (TOC) and chemical oxygen demand (COD) was achieved 84.2 and 94.6% respectively, after 3.5h under visible light irradiation at an initial pH of 3.5. The catalytic removal of toluene followed a pseudo-first-order reaction. The toluene removal in the dark phase indicated that nonpolar toluene molecules are initially sorbed onto the porous structure of CB-TiO2-FeO via electrostatic bonding between nonpolar molecule moieties with phenolic surface of CB-TiO2-FeO. The greatly enhanced photocatalytic performance of CB-TiO2-FeO mainly stemmed from their strong visible-light-harvesting ability of photo-generated electron–hole pairs.

Chelating magnetic copolymer composite modified by click reaction for removal of heavy metal ions from aqueous solution

Novel chelating magnetic copolymer beads in micron-size range were prepared by suspension polymerization and click reaction. The click chemistry was proposed as a tool for tuning the surface functionality of magnetic poly(vinylbenzyl chloride-co-styrene-co-divinyl benzene), M-PVBC, by a covalent attachment with propargyl alcohol via triazole formation. After click-coupling reaction, the changes in surface morphology and chemical functionality were examined by SEM–EDX and FT-IR, respectively. Adsorption characteristics for heavy metal were investigated by a batch adsorption in an aqueous system under different experimental conditions. The adsorption process was pH, concentration and time dependent. The maximum adsorption capacities of the chelating magnetic copolymer, M10-PVBC-C, for Zn(II), Cu(II) and Ni(II) in 500ppm solutions were 67.29, 61.20 and 57.18mg/g, respectively. Adsorption of Cu(II) ion, the model heavy metal ion, was well fitted to the Langmuir isotherm model. The magnetic chelating beads could be rapidly recovered from aqueous solution by an external magnetic field, regenerated and reused for 5 cycles without significant lost in adsorption capacity. The results of this work indicated that the surface functionalization by click reaction could be a simple and suitable method for the preparation of polymeric adsorbents for an effective removal of metal ions from aqueous solution.

Liquid–liquid dispersion in a continuous oscillatory baffled reactor – Application to suspension polymerization

Reducing energy costs, improving safety, minimizing waste are the current aims of chemical engineering. Process intensification in fine chemistry has been extensively studied but less work refers to heterogeneous reactions involving two liquid phases. This paper focuses on batch to continuous suspension polymerization transposition and especially on the liquid–liquid dispersion step. The main features of suspension polymerization reaction are based on (i) the initial liquid–liquid dispersion requiring a controlled size and narrow distribution and (ii) on the control of the final particle size during the agglomeration step by avoiding fouling which is a bottleneck for continuous flow. For the continuous transposition, liquid–liquid dispersion and reaction studies are carried out in continuous oscillatory baffled reactor (COBR) which is a multipurpose reactor. Its suitability to overcome the bottlenecks is demonstrated through the investigation of the oscillating and flow conditions or the dispersed phase holdup. A controlled droplet size distribution can be achieved. Oscillation is the main parameter responsible for droplet breakage. The suitable conditions to obtain stable dispersion are determined. For one of the first times, COBR is used for suspension polymerization.

Effect of Agitation on Density of Poly(vinyl acetate) Particles Produced in Suspension Polymerization Reactions

AbstractPoly(vinyl acetate) particles are produced through suspension polymerization reactions at different agitation speed. As expected, particle size distributions are strongly affected by the increasing speed of agitation. Surprisingly, the latter also causes the decrease of particle densities, which can be explained by encapsulation of small water droplets by the viscous reacting medium. Encapsulation of water droplets can lead to the formation of hollow particles that can be observed through microscopic analyses.

A magnetic sorbent for the efficient and rapid extraction of organic micropollutants from large-volume environmental water samples

A magnetic solid-phase extraction (MSPE) method based on a novel magnetic sorbent was proposed for the extraction of target compounds from large-volume water samples. First, magnetic hypercrosslinked microspheres (NAND-1) were prepared via membrane emulsification–suspension polymerization and post crosslinking reaction. To ensure that the Fe3O4 nanoparticles could completely pass through the membrane without blocking the pores, oleic acid was used to modify the Fe3O4 nanoparticles, which enhanced lipophilicity and monodispersity of the magnetite nanoparticles. The obtained NAND-1 microspheres exhibited super paramagnetic characteristics and excellent magnetic responsiveness with a saturation magnetization of 2.53emu/g. In addition, a uniform particle size (∼8μm) and a large average surface area (1303.59m2/g) were also observed, which were both beneficial for the extraction of the target compounds. Thus, NAND-1 has the potential to simultaneously exhibit good extraction efficiencies toward different types of organic micropollutants (OMPs), including triazines, carbamazepine and diethyl phthalate. The conditions of the MSPE based on NAND-1 were optimized by single factor and orthogonal design experiments. This MSPE method needed only a small amount of sorbent (50mg/L) for the extraction of OMPs from a large-volume aquatic sample (5L) and reached equilibrium in a short amount of time (30min). Moreover, the solution volume, the pH, and the salinity had insignificant influences on the extraction of the eight target OMPs. Under the optimum conditions, the recoveries of the eight OMPs calculated by analyzing the spiked samples were from 91.7% to 99.4%. The NAND-1 could be recycled ten times and still achieve recoveries of the eight OMPs higher than 86%. The limits of detection of the eight OMPs ranged from 1.76 to 27.56ng/L, and the limits of quantification were from 5.71 to 92.05ng/L. These results indicated that the proposed method, based on the use of NAND-1 as a magnetic sorbent, has the advantages of convenience and high efficiency and can be successfully applied to analyze the OMPs in real water samples.

In Situ Incorporation of Recycled Polystyrene in Styrene Suspension Polymerizations

In the present work, the in situ incorporation of polystyrene in styrene suspension polymerization reactions is studied, aiming at recycling discarded and off-spec polymer materials. A number of issues related to the effects of the incorporated material on the reaction kinetics and on some polymer properties are studied. It is noticed that the monomer conversion trajectories are not affected by the polymer incorporation, unlike the average molar masses, when initial polymer contents are similar. It is also noticed that the incorporation of polymer samples with low and high average molar masses leads to similar kinetic effects, showing that the Free Volume Theory describes well the gel effect in these systems. A mathematical model is developed to simulate the polymerization reaction, taking into account the average molar mass and concentration of the incorporated polymer resin.