Dispersion Polymerization Of Styrene Research Articles

Preparation of Surface-Wrinkled Silica-Polystyrene Colloidal Composite Particles.

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

Enhancing cement hydration by core/shell PS@SiO2 nanoparticles

Nanoparticles are widely used in construction. Here, nano-SiO2 is employed, in a way that prevents agglomeration of the nanoparticles, as pozzolanic material to improve Portland cement hydration and to improve the properties of the concrete. To explore the effect of nano-SiO2 and core-shell PS@SiO2 on cement properties, spherical polystyrene particles were prepared by dispersion polymerization of styrene in polar solvents and characterized by FTIR and E-SEM. The core shells PS@SiO2 were synthesized by Stöber method. The results showed an amorphous nano-SiO2 layer can be deposited uniformly on polystyrene particles. This core/shell structure was reducing the aggregation of nano-SiO2 effectively. It was shown that PS@SiO2 particles improved the concrete performances compared to blended cement with nano-SiO2 due to the agglomeration affect. Highlights • Core/shell PS@SiO2 nanoparticles with a uniform coating layer were prepared. • As-prepared nanoparticles were characterized by a variety of advanced methods. • Nanoparticles accelerate hydration and lower the spatial weight of cement paste. • Core/shell nanoparticles improve cement hydration much better than nano-SiO2.

Capturing Acidic CO2 Using Surface-Active Difunctional Core-Shell Composite Polymer Particles via an Aqueous Medium.

Multifunctional surface-active polymeric composites are attractive materials for the adsorption of various small molecules. Herein, dual-functionalized micron-sized surface-active composite polymer particles were prepared by a three-step process for CO2 adsorption. First, polystyrene (PS) seed particles were prepared via the dispersion polymerization of styrene. PS/P(MMA-AAm-EGDMA) composite polymer particles were then synthesized by aqueous seeded copolymerization of methyl methacrylate (MMA) and acrylamide (AAm) in the presence of an ethylene glycol dimethacrylate (EGDMA) cross-linker. Finally, the amide moieties of PS/P(MMA-AAm-EGDMA) composite particles were converted into an amine-functionalized composite by using the Hofmann degradation reaction. The presence of primary amine groups on the surface of aminated composite particles was confirmed by some conventional chemical routes, such as diazotization and Schiff's base formation reactions. The formation and functionality of the PS seed, PS/P(MMA-AAm-EGDMA), and aminated PS/P(MMA-AAm-EGDMA) composite polymer particles were confirmed by Fourier transform infrared (FTIR) spectra analyses. Scanning electron microscopy (SEM) analysis revealed spherical shape, size, and surface morphologies of the PS seed, reference composite, and aminated composites. The elemental surface compositions, surface porosity, pore volume, pore diameter, and surface area of both composite particles were evaluated by energy-dispersive X-ray (EDX) mapping, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses. Dynamic light scattering (DLS) and ζ-potential measurements confirmed the pH-dependent surface properties of the functionalized particles. The amount of the adsorbed anionic emulsifier, sodium dodecyl sulfate (SDS), on the surface of aminated PS/P(MMA-AAm-EGDMA) is higher at pH 4 than that at pH 10. A vice versa result was found in the case of cationic surfactant, hexadecyltrimethylammonium bromide (HTABr), adsorption. Synthesized aminated composite particles were used as an adsorbent for CO2 adsorption via bubbling CO2 in an aqueous medium. The changes in dispersion pH were monitored continuously during the adsorption of CO2 under various conditions. The amount of CO2 adsorption by aminated composite particles was found to be 209 mg/g, which is almost double that of reference composite particles.

Revisiting the preparation of cylindrical polystyrene particles by magnetic stirring

The cylindrical shape is one of the most common shapes in geometry. The preparation of cylindrical polystyrene (PS) particles by magnetic stirring has been previously reported (Angew. Chem. Int. Ed.2018, 57, 9936–9940) via two steps: spherical PS particles were synthesized by dispersion polymerization of styrene with polyvinylpyrrolidone (PVP) as the stabilizer, followed by stirring the spherical PS particles in a water medium in the presence of PVP. However, the effects of various parameters on the deformation were not fully investigated. Herein we report full details of the preparation of cylindrical PS particles by stirring at room temperature. The influence of PVP molecular weight in the polymerization process, and various stirring parameters such as the molecular weight of PVP for stirring, concentration of PVP for stirring, stirring time, stirring rate, size of stirrer and amount of the mixture for stirring on the morphology of the resulting particles was investigated systematically. Moreover, a larger glass vial and correspondingly a larger magnetic stirrer were used in this work, which could produce cylindrical polymer particles at a five-fold larger scale. However, the production of cylindrical polymer particles at a even (fifty-fold) larger scale was less successful and might lead to a substantial part of peanut-shaped particles. This work is expected to be useful for improved understanding of the formation of these cylindrical polymer particles.

Polymerization‐induced self‐assembly of amino‐acid‐based nano‐objects by reversible addition–fragmentation chain‐transfer dispersion polymerization

AbstractA series of amino‐acid‐based amphiphilic diblock copolymer nano‐objects having different morphologies were developed by reversible addition–fragmentation chain‐transfer (RAFT) dispersion polymerization of styrene (St) in methanol. This was mediated by six different hydrophilic poly(N‐acryloyl amino acid) macro‐chain transfer agents (CTAs), including three carboxylic‐acid‐containing ones, poly(N‐acryloyl‐l‐proline) (PAProOH), poly(N‐acryloyl‐4‐trans‐hydroxy‐l‐proline) (PAHypOH), and poly(N‐acryloyl‐l‐threonine) (PAThrOH) prepared by RAFT polymerization, and their methyl ester forms, PAProOMe, PAHypOMe, and PAThrOMe. The effects of polymerization conditions on RAFT dispersion polymerization of St using a dithiocarbamate‐terminated PAProOH was investigated. A systematic study of the effects of monomer conversion and concentration afforded the formation of various morphologies (i.e., spheres, worms, and vesicles). The effects of hydrogen‐bonding and ionic interactions of the macro‐CTAs on the assembled structures of the nano‐objects were evaluated using six different macro‐CTAs. Transforming the products from methanol to water via dialysis produced amino‐acid‐based block copolymer nano‐objects, exhibiting pH‐responsive morphological change, in aqueous solution.

PH-Switchable Latexes Based on the Nonionic Amphiphilic Diblock Copolymer with a Chargeable End-Group on the Core-Forming Block

Reversible addition-fragmentation transfer (RAFT) dispersion polymerization of styrene was performed in an ethanol-water mixture using a Z-group carboxylated poly(N-acryloylmorpholine) (PNAM) macro-RAFT agent, and dialysis was performed against water to produce the PNAMx-PSy-COOH (PS = polystyrene) diblock copolymer latexes. This new formula is developed for the fabrication of pH-switchable copolymer latexes through an end-group response approach. The PNAM44-PS134-COOH latex is unstable at suitably low pH values (pH ≤ 4), and these aggregated spherical nanoparticles are redispersed successfully by adding base as determined by analysis of their dynamic light scattering (DLS) diameters and transmission electron microscopy (TEM) data. Negative zeta potential (-19.4 mV at 0.02% w/w) of the original latex indicated that carboxylic acid end-groups were anchored on the surface of the PS core via the polymerization-induced self-assembly (PISA) process and exposed to the solvent. Protonation of carboxylate groups reduces the degree of hydration of the PS core with a great impact on the free energy of the core/solvent interface, inducing the aggregation of PNAM44-PS134-COOH latex particles. A comparative experiment where the carboxylic acid end-group is designed on the PNAM stabilizer block proves that no pH-switchable behavior occurs in this case. Moreover, the vesicle-like nanoparticles composed of PNAM44-PS428-COOH copolymers have an apparently anionic character (zeta potential ≈ -33.5 mV at 0.02% w/w) and are still pH-switchable with a lower critical flocculation point (pH 2-3). More importantly, the latex composed of PNAM118-PS151-COOH diblock copolymers is insensitive to the solution pH.

Preparation of cylinder-like polystyrene-silica composite particles

The cylinder-like shape is one of the most common shapes in geometry and polymer-silica composite particles have been one of the most commonly reported organic-inorganic composite particles, while cylinder-like polymer-silica composite particles are seldom reported in literature. In this work, we report a facile method to prepare cylinder-like polystyrene-silica (PS–SiO2) composite particles by judicious combination of PVP-involved dispersion polymerization and magnetic stirring. First, spherical PS-SiO2 composite particles were synthesized by dispersion polymerization of styrene in an ethanol/water mixture. Second, cylinder-like PS-SiO2 composite particles were prepared by stirring the spherical PS-SiO2 particles in a water medium in the presence of PVP. The effects of PVP molecular weight, PVP concentration, stirring rate, stirring time and stirring temperature on the morphology of the composite particles were investigated. Optimization of the stirring conditions allowed relatively high percentage (up to ~73%) of cylindrical particles to be achieved. This method is expected to expand the morphology library of polymer-silica composite particles.

Preparation and Characterization of Prussian Blue Coated Polymeric Nanoparticles via Dispersion Polymerization Template

Herein, we report a novel method for the synthesis of Prussian blue/PB containing polymeric hybrid nanoparticles. This method employs poly(4-vinylpyridine)/P4VP stabilized polystyrene/PS nanoparticles as a template to define the position of Prussian blue product. In the first step, the templates of P4VP-stabilized polystyrene polymer nanoparticle were prepared by dispersion polymerization of styrene in methanol/water in the presence of macro-P4VP chain transfer agents. With the addition of sodium pentacyanoammineferroate(II) hydrate/[Fe(CN)5NH3]3− into dispersion, pyridyl moieties in P4VP in polymeric nanoparticles could react with [Fe(CN)5NH3]3− through a ligand exchange reaction. Subsequent metal coordination polymerization of Fe3+ with ferrate confined within the surface of the nanoparticles led to the generation of monodispersed PB coated polymeric nanoparticles. The nanoparticles were characterized and confirmed by various modern techniques such as FT-IR, UV–Vis, TGA, XPS, TEM, SEM and AFM. The UV–Vis, FT-IR, TGA and XPS studies suggested Prussian blue was successfully coordinated with P4VP-PS polymers template according to our experimental design. The morphology studies indicated that spherical nanoparticles were obtained. In particular, the EDX mapping results clearly show that the iron element is evenly distributed on the nanoparticles. In addition, two parameters, including the amount of initiator and the amount of iron in the system, have important effects on the particle size and distribution. This experimental system we designed has great potential for the synthesis of metal containing polymeric nanoparticles with other compositions and morphologies, which offers many possibilities worthy of further exploration.

Preparation of Dimpled Polystyrene-Silica Colloidal Nanocomposite Particles.

Preparation of polymer-silica colloidal nanocomposite particles with concave shape is challenging and seldom reported. This paper presents a novel and facile method to prepare dimpled polymer-silica nanocomposite particles with a thin silica shell through the judicious combination of alcoholic dispersion polymerization and the decane evaporation method. Submicrometer-sized polystyrene-silica (PS-SiO2) nanocomposite particles were first prepared by dispersion polymerization of styrene in methanol in the presence of a methanolic silica sol, and then dimpled PS-SiO2 particles were prepared by heating the near-spherical PS-SiO2 particles dispersed in methanol/water media in the presence of decane and subsequent cooling. The effects of different heat treatment parameters, such as methanol/water ratio, stirring temperature, and stirring rate on the formation of the nanocomposite particles were investigated. Optimization of the heating conditions allowed ∼100% of dimpled particles to be achieved with one dimple on each particle. Moreover, calcination of the dimpled PS-SiO2 nanocomposite particles led to the formation of hollow dimpled particles with a thin silica shell. This method is expected to enrich the shapes of polymer-silica nanocomposite particles.

Novel Preparation of Monodisperse Poly(styrene-co-divinylbenzene) Microspheres by Controlled Dispersion Polymerization

Poly(styrene-co-divinylbenzene) particles possessing uniform properties are attractive for various chromatographic applications. However, their preparation by dispersion polymerization is rather complicated. Our aim was to prepare monodisperse PS microspheres by dispersion polymerization of styrene with controlled addition of 1 wt % of divinyl benzene. The reaction occurs in a mixture of ethanol with 2-methoxyethanol or 2-ethoxyethanol and is stabilized and initiated by hydroxypropyl cellulose and dibenzoyl peroxide, respectively. The effects of the medium polarity based on changing of the solvent mixture ratio and several modes of divinyl benzene addition, including simple one-shot and continuous divinyl benzene post-addition, on the particle size and morphology are investigated. Slow continuous dosing of 1 wt % of divinyl benzene one hour after the start of the styrene polymerization produce monodisperse spherical PS particles 5.4 μm in size. Such microspheres might be suitable as precursor for a solid adsorbent for harmful and carcinogenic organic vapors.

Role Transformation of Poly( N-isopropylacrylamide) Microgels from Stabilizer to Seed in Dispersion Polymerization by Controlling the Water Content in Methanol-Water Mixture.

Poly( N-isopropylacrylamide) (PNIPAM)-based ionic microgels with different diameters were first prepared and then used as particulate stabilizer or seed in dispersion polymerization of styrene. The role of PNIPAM-based ionic microgels could be transformed from particulate stabilizer to seed by controlling the water content in methanol-water mixture. Generally, PNIPAM-based ionic microgels served as particulate stabilizer in methanol in the absence of water, leading to the formation of spherical polystyrene nanoparticles. However, they turned into seeds when water was added into the methanol solution, with the formation of octopus-like nanoparticles. Further study demonstrated that the mechanism for this role transition was related to the special thermosensitivity of PNIPAM microgels in methanol-water mixture. They lost their thermosensitivity in pure methanol solution but restored their thermosensitivity when increasing the water content in methanol-water mixture.

Modeling particle size in the dispersion polymerization of styrene using artificial neural network and genetic algorithm

Artificial neural network (ANN) combined with genetic algorithm (GA) method was employed to predict the particle size and particle size distribution in the dispersion polymerization of styrene stabilized by polyvinyl pyrrolidone in ethanol. A D-optimal split-plot design was utilized to obtain the 70 required experiments using the Expert Design 9 software. The restricted maximum likelihood (REML) method was employed in order to model the effect of reaction parameters on the particle size and particle size distribution. A back propagation learning algorithm with adaptive learning rate was used to train the neural network. The number of neurons in each hidden layer of the network was determined by applying genetic algorithm. Two thirds of the experimental data were randomly used for network training, and the remaining data were utilized to determine the validity of the network. This procedure was repeated 100 times for cross-validation. The average R 2 for modeling the validation data set for the particle size and the particle size distribution were 0.95 and 0.92, respectively. The average R 2 for modeling the training data set for the particle size and the particle size distribution were 0.97 and 0.95, respectively. Although using all the experimental data for building the model in the REML method, the R 2 for modeling the particle size and particle size distribution were 0.92 and 0.89, respectively. It can be concluded that ANN is a more powerful tool for modeling the particle size and particle size distribution.

Effect of Monomers in Vinyl Urethane Macromonomers on Dispersion Polymerization of Polystyrene

The four different vinyl monomers in the reaction of isocyanate-terminated polyurethane prepolymer were used for the preparation of macromonomers and successfully employed in the dispersion polymerization of styrene. The chemical structures of vinyl monomer in macromonomers influenced on the polystyrene particle characteristics, such as the conversion, weight average molecular weights (Mw), polydispersity index (PDI), weight average diameter (Dw), and uniformity. The conversion of polystyrene increased with amounts of methyl group in vinyl monomer. Also the uniformity of polystyrene particles increased with amounts of methyl group in vinyl monomer.

Facile preparation of Fe3O4/mesoporous TiO2 nanoparticles shell on polystyrene beads and its effective absorption of cyanobacteria in water

In this letter, a facile method were used to prepare raspberry-like polystyrene-magnetite mesoporous titanium dioxide particles (PS-Fe3O4/mTiO2), which have potential application in handling pollutants floated on water such as cyanobacteria. This method involved the dispersion polymerization of styrene with Fe3O4/mTiO2 nanoparticles modified by vinyltrimethoxysilane (VTMS) where 2, 2-azobisisobutyronitrile (AIBN) was used as initiator. When VTMS was applied, the Fe3O4/mTiO2 nanoparticles loaded on the surfaces of PS beads homogeneously while weak loading occurred when VTMS was absent. The homogeneous loading resulted from the fact that VTMS could strengthen the force between PS beads and Fe3O4/mTiO2 nanoparticles, meaning that VTMS was effective in loading the Fe3O4/mTiO2 nanoparticles on PS beads. The as-prepared materials had high hydrophobic surfaces, and low density. After the resulting composite was loaded on the surfaces of cyanobacteria and separated by magnetic field, the magnetic properties of Fe3O4 was retained, indicating that this composite could remove cyanobacteria in water effectively. Our results provide insight into the water-treatment of pollutants.

Facile Preparation of Litchi-Like Polystyrene-Silica Hybrid Particles via Dispersion Polymerization

The composite particles with litchi-like morphologies attributing to the combination of inorganic silica seed and polymer nodules were synthesized successfully using a modified dispersion polymerization method. Dispersion polymerization of styrene was achieved in the presence of silica particles and the formed polystyrene nanoparticles were absorbed onto the surface of silica particles. The effects of the adding amount of St monomer on the particle morphologies was investigated.

Multicompartment Nanoparticles of Poly(4-vinylpyridine) Graft Block Terpolymer: Synthesis and Application as Scaffold for Efficient Au Nanocatalyst

Multicompartment nanoparticles (MCBNs) constructed with the brush block terpolymer of [poly(p-chloromethylstyrene)-graft-poly(4-vinylpyridine)]-block-polystyrene (PCMS-g-P4VP)-b-PS are prepared through dispersion polymerization of styrene in the methanol/water mixture mediated by the brush macro-RAFT agent of poly(p-chloromethylstyrene)-graft-poly(4-vinylpyridine) trithiocarbonate. During the dispersion RAFT polymerization, the molecular weight of the brush (PCMS-g-P4VP)-b-PS block terpolymer linearly increases with the monomer conversion. Ascribed to the brush (PCMS-g-P4VP) block, MCBNs including a PS core and discrete subdomains of (PCMS-g-P4VP) on the PS core dispersed in water are formed. The reasons leading to formation of MCBNs are discussed, and the immiscibility of the brush (PCMS-g-P4VP) block with the PS core, the low number density of the brush (PCMS-g-P4VP25)21 chains tethered on per surface area of the PS core, and the high molecular weight but the low polymerization degree of the brush (PCMS...

Preparation of raspberry-like ZIF-8/PS composite spheres via dispersion polymerization.

Raspberry-like ZIF-8/PS composite spheres are prepared via dispersion polymerization of styrene with ZIF-8 and PVP as co-stabilizers. PVP is found to be crucial in determining morphology of the final product. It helps adherence of ZIF-8 nanoparticles to PS spheres. It is found that ZIF-8 nanoparticles thus prepared are partially embedded into PS sphere surfaces, resulting in a stable raspberry-like structure. Surface coverage of ZIF-8 can reach up to ∼32%. The effects of ZIF-8 content and PVP concentration on the particle size and morphology are examined in detail with the mechanisms elucidated. The raspberry-like spheres can be used as a template to grow thick ZIF-8 layers on the PS spheres through subsequent solvothermal treatment, leading to the formation of polymer-core MOF-shell structure.

분산중합에 의한 폴리스티렌-폴리에테르이미드 코어-셀 입자의 합성

Polystyrene-poly(etheramic acid) core-shell particles were prepared by dispersion polymerization of styrene using poly(etheramic acid) obtained by the reaction of 2,2`-bis[4-(3,4-dicarboxyphenoxy) phenyl]propane dianhydride and 3,5-diamniobenzoic acid as a stabilizer. 4-Vinylbenzyltrimethylammonium chloride was used as a comonomer to increase the binding efficiency of poly(etheramic acid). When the ethanol-water mixture (7 : 3) was used as a reaction medium, particles were stabilized well and the size distribution of particles was fairly narrow. The particle size increased with the amount of styrene. The particles polymerized in the dimethylformamide-water mixture had a broad size range. Polystyrene-poly(etheramic acid) core-shell particles were transformed to polystyrene-polyetherimide core-shell particles by the chemical imidization of shells.

Surface patterning of micron-sized aluminum flakes by seeded dispersion polymerization: Towards waterborne colored pigments by gold nanoparticles adsorption

The concomitant polymer embedding and surface patterning of micron-sized aluminum flakes by dispersion polymerization of styrene is reported. The aluminum pigments coated by a thin silica layer were modified by trimethoxysilylpropyl acrylate grafting (TMSPA-grafted Al@silica). Dispersion polymerization of styrene was further performed in alcoholic or hydro-alcoholic media in the presence of the organically modified TMSPA-grafted Al@silica pigments as a seed and poly(N-vinylpyrrolidone) (PVP) as a steric stabilizer to lead to hybrid aluminum flakes. The weight fraction of polymer onto the aluminum pigment surface was tuned from 14 to 29 wt.% by the hydro-alcoholic continuous phase composition and from 19 to 38 wt.% by the initiator content. The chemical nature of the initiator plays an important role in the surface patterning of the hybrid aluminum flakes as 2,2′-azobis(isobutyronitrile) initiator provided polymer nodules, i.e. due to a pattern of polymer protrusions with nodules shape at the surface of the inorganic substrate, while a flat and continuous polymer layer was obtained with 2,2′-azobis(2-amidinopropane) dihydrochloride initiator. Moreover, the introduction of ammonium groups at the surface of the polymer particles was possible by the delayed addition of a cationic acrylate co-monomer ([2-(acryloyloxy)ethyl]-trimethylammonium chloride) rendering the pigments dispersible in water. Finally, gold nanoparticles were successfully deposited onto the micro-patterned aluminum flakes to open the way towards new colored aluminum pigments. Both location of cationic ammonium function in the polymer nodule and nature of gold nanoparticles ligands were investigated with the aim to evaluate the amount of adsorbed gold nanoparticles. The final hierarchically patterned aluminum pigments dispersed in water exhibited an intense purple color.

Shape of the Particles Produced by Seeded Dispersion Polymerization of Styrene

Shape of the Particles Produced by Seeded Dispersion Polymerization of Styrene