Facile Method to Synthesis of Golf Ball-Like Particles via Early-Ceased Seeded Dispersion Polymerization

Golf ball-like poly(methyl methacrylate) particles were produced via seeded dispersion polymerization of 2-ethylhexyl methacrylate with poly(methyl methacrylate) seed beads in the presence of saturated hydrocarbon droplets and evaporation of the hydrocarbon after the polymerization. It was observed that the particles are acquired in the form of a stable dispersion if the reaction is ceased around 42% of monomer conversion. Moreover, the effect of different reaction conditions (e.g. hydrocarbon and stabilizer type, initiator and monomer content, and polarity of the medium) on the shape and stability of the produced particles was investigated. It was revealed that the number and size of the dents on the surface of the golf ball-like particles could be manipulated easily with a simple change in each one of the parameters referred to above. In addition, the experimental results showed that some of the particles become unstable and diffuse into each other during polymerization, resulting in the formation of huge golf ball-like objects. The production of disk-like poly(methyl methacrylate) particles via fully developed seeded dispersion polymerization in the presence of a hydrocarbon which owns lengthy alkyl chain was another interesting finding of this study.     

PMMA stereocomplex: Study of the aggregation process by electron microscopy

The structure of stereocomplex aggregates formed from isotactic and syndiotactic poly (methyl methacrylate)s was studied in tetrahydrofuran (THF) by transmission electron microscopy (TEM). We have found that the primary stereocomplex particles are nearly spherical and, as the complexation advances, the particles lengthen. Eventually aggregates branch to form a three-dimensional network.     

Dispersion polymerization of methyl methacrylate in supercritical CO2 in the presence of non-fluorous random copolymers

A series of non-fluorous random copolymers, composed of 3-[tris(trimethylsilyloxy)silyl] propyl methacrylate and 2-dimethylaminoethyl methacrylate, poly(SiMA-co-DMAEMA) with different comonomer ratios were prepared and utilized as stabilizers for the free radical dispersion polymerization of methyl methacrylate (MMA) in supercritical carbon dioxide (scCO₂). It was demonstrated that the composition and concentration of the stabilizer have a dramatic effect on the morphology of resulting poly methyl methacrylate (PMMA) latex. When the copolymeric stabilizer poly(SiMA-co-DMAEMA) (71:29) was employed, free-flowing spherical PMMA particles were produced in high yield. As the concentration of stabilizer increases, the resulting size of colloidal particles decreases. In addition, the monomer concentration and initial pressure affected the particle diameter of PMMA.     

Synthesis of block copolymer-stabilized Au-Ag alloy nanoparticles and fabrication of poly(methyl methacrylate)/Au-Ag nanocomposite film

[Poly(2-(N,N-dimethylamino)ethyl methacrylate)]-b-poly(methyl methacrylate)-b-[poly(2-(N,N-dimethylamino)ethyl methacrylate)] (M(n)=45,000; 20K-5K-20K; PDI = 1.2) block copolymer surfactant stabilized amphiphilic gold-silver alloy nanoparticles (Au-Ag(PDMA-b-PMMA-b-PDMA)) has been synthesized in both water and in organic medium. The block copolymer stabilized pre-made alloy nanoparticles were successfully dispersed in hydrophobic poly(methyl methacrylate) homopolymer matrix (PMMA) of molecular weight 30,000. The successful synthesis of alloy nanoparticles was accessed by Transmission Electron Microscope (TEM), Energy Dispersed X-ray (EDX), and UV-visible spectrophotometric analysis. The surface functionality of the nanoparticles was confirmed by quantitative determining the grafting density of polymer chain around the nanoparticle surface using combination of thermo gravimetric (TGA) and TEM analysis. The hydrodynamic diameter of the alloy particles including the polymer chains was obtained from dynamic light scattering measurement (DLS). The mechanism of synthesis of high concentration of Au-Ag alloy particles from HAuCl(4) and AgNO(3) (in presence of Cl(-) from reduction of gold salt) metal particles precursors and the successful preparation of poly(methyl methacrylate)/gold-silver nanocomposite films have been discussed.     

Thermal degradation of copolymers of methyl methacrylate and 2,6-dimethoxycarbonyl-1,6-heptadiene

The thermal degradation under vacuum of copolymers of methyl methacrylate and 2,6-dimethoxycarbonyl-1,6-heptadiene of different compositions has been investigated. It has been found that the presence in the polymer chains of small amounts of cyclic structural units from the diene monomer considerably reduces the amount of degradation which occurs in poly(methyl methacrylate) at temperatures lower than 300°C. On the basis of the results of the analysis of the degradation products, a mechanism is suggested which accounts for this effect.     

Shape of the particles produced by seeded dispersion polymerization of styrene

In this work, seeded dispersion polymerization of styrene was carried out in the presence of various types of seed particles. We found that in the case of polystyrene and poly(methyl methacrylate) seeds, the shape of the resulting particles remained spherical. For styrene/poly(nbutyl methacrylate) (PnBMA) and styrene/poly(lauryl methacrylate) seeding particles, raspberry like particles were produced along with those of occluded morphology. We studied the effects of various polymerization factors such as concentrations of a stabilizer, an initiator, and a monomer, a weight ratio of methanol to water, a type of initiator, weight ratio of styrene to Pn-BMA seed particles, and polymerization temperature on the formation of these raspberry-like particles. The experimental results showed that the increase of concentrations of the initiator and the stabilizer as well as that of methanol favors the formation of such particles by increasing their surface roughness. An increase of the temperature of polymerization had the same effect on the morphology of resulting product. We hypothesized that the nucleation and growth of specifically fine-structured polystyrene domains on the surface of the Pn-BMA particles guides the formation of non-linear morphology during seeded polymerization in colloidal solution.     

Fracture surface morphology and phase relationships of polystyrene/poly(methyl methacrylate) systems. I. Low-molecular-weight polystyrene in poly(methyl methacrylate)

Samples of low-molecular-weight polystyrene (PS) in poly(methyl methacrylate) (PMMA) were prepared by first dissolving PS in methyl methacrylate monomer and then polymerizing the monomer. Forty-three specimens of varying number-average molecular weight (2100–49,000) and composition (5–40 wt %) of PS were prepared, and the surface morphology and phase relationships studied by scanning electron microscopy. Four distinct types of phase relationships were observed: (i) a single phase consisting of PS dissolved in PMMA; (ii) PS dispersed in PMMA; (iii) PMMA dispersed in PS; and (iv) regions of PS dispersed in PMMA coexisting with regions of PMMA dispersed in PS. Values of the size and population density of the dispersed particles are reported. Finally, the size and distribution of the dispersed particles and the various types of phase relationships are discussed in terms of the ternary polystyrene/poly(methyl methacrylate)/methyl methacrylate phase diagram.     

AN ATOMIC FORCE MICROSCOPY STUDY ON THE AGGREGATION OF ISOTACTIC POLY（METHYL METHACRYLATE）

Aggregation process of isotactic poly(methyl methacrylate) (i-PMMA) has been studied extensively for many years, and considerable progress has been made in both experimental and theoretical studies. They are, however, seldom sustained by real-space observations of the underlying morphology. In this paper, the aggregation process of i-PMMA in concentrated acetone solutions and the fractal structure of the resulting three-dimensional clusters were characterized on the basis of real-space AFM observations of their two-dimensional projection. It was found that spherical multiple-chain particles formed upon collapse and aggregation of the involving chains as a whole during quenching the solution to room temperature. By keeping the solution at room temperature, the initially formed particles stick together upon contact to form larger particles through reassembling very slowly. The succeeding collision of the enlarged spherical particles leads to the formation of small clusters. These newly formed small clusters grow when they meet with other clusters or single Brownian particles. This leads to the formation of large clusters with fractal dimension of 1.95$±0.05, which suggest a reaction-limited cluster aggregation of i-PMMA in a concentrated acetone solution. This is in accordance with the conclusion obtained by light scattering measurements.     

Two-dimensional ordered arrays of monodisperse silica particles grafted with concentrated polymer brushes

Hybrid particles which have a core of monodisperse silica particle and a shell of well-defined poly(methyl methacrylate) chains end-grafted on the core surface with a surface density as high as 0.8 chains/nm² were prepared by surface-initiated atom transfer radical polymerization of methyl methacrylate with an initiator-fixed silica particle. Monolayers of the hybrid particles were formed at the air-water interface by depositing a defined amount of the particle suspension onto water surface. Transmission electron microscopic and atomic force microscopic observations of these monolayers showed that the hybrid particles formed a two-dimensional hexagonally ordered lattice with a wide controllability of interparticle distance. This lattice structure was utilized as a template for the fabrication of a negatively patterned surface of poly(dimethylsiloxane) elastomer.     

Control of particle size in dispersion polymerization of methyl methacrylate

Poly(methyl methacrylate) (PMMA) particles ranging in diameter from 2 to 10 μm were prepared by dispersion polymerization. The effects of various polymerization parameters on the size and monodispersity were systematically investigated. The particle size was found to increase with increasing polymerization temperature, concentration and decomposition rate of the initiator, and solvency of the dispersion medium. It also increased with increasing concentration and molecular weight of the polymeric stabilizer, poly(vinyl pyrrolidone) (PVP). As the monomer concentration was increased from 5 to 20 wt %, a minimum was found in the particle size at a monomer concentration of 10 wt %. A costabilizer was found to be necessary for preparing monodisperse particles at stabilizer concentrations below 2 wt %. A recycling experiment showed that the consumption of PVP was quite small in each cycle and the residual materials in this system could be reused readily. © 1993 John Wiley & Sons, Inc.     

Preparation of nonspherical particles via dual-seeded dispersion polymerization in the presence of saturated hydrocarbon droplets

In this study, the effect of various polymerization conditions on the shape of the particles produced by dual-seeded dispersion polymerization of a second monomer with polystyrene (PS) and poly(methyl methacrylate) (PMMA) seed particles in the presence of saturated hydrocarbon droplets in a polar media was discussed. It was observed that with changing the affinity between the hydrocarbon and PS seed particles, second monomer type, polarity, and alcohol type of the medium nonspherical particles with a variety of shapes can be produced. Furthermore, we suggested that the presence of PMMA seed particles in the medium affects the distribution of the second polymer domains on the surface of the PS seed particles in addition to the absorbed amount of the hydrocarbon by PS particles and second polymer domains and the distribution of the hydrocarbon between them. Moreover, the experimental results showed that almond shell-like PS particles can be prepared under certain conditions.     

Dispersion polymerization of 2-hydroxyethyl methacrylate (HEMA) using siloxane-based surfactant in supercritical carbon dioxide and in compressed liquid dimethyl ether

The free radical dispersion polymerization of 2-hydroxyethyl methacrylate (HEMA) has been carried out in supercritical carbon dioxide (scCO₂) and compressed liquid DME using several surfactants. The polymerization are performed in the presence of fluorine-based poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl acrylate) [poly(HDFDA)], poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate) [poly(HDFDMA)], or poly(HDFDMA-co-MMA) and siloxane-based PDMS-g-pyrrolidonecarboxylic acid (Monasil PCA™) or PDMS modified surfactants, SS-5050K™ and KF6017™ as polymerization surfactants. When scCO₂ was used as a polymerization medium, the PHEMA were heavily agglomerated. However, the spherical and relatively uniform poly(2-hydroxyethyl methacrylate) (PHEMA) particles could be produced even at 20 bar, with a narrow particle size distribution in compressed liquid DME. It was observed that fluorine-based surfactants were not a good surfactant as siloxane-based surfactants for the dispersion polymerization of HEMA. The average particle size of PHEMA was shown to be dependent on the type of the surfactant, the amount of the surfactant and initiator added to the system. The effect of two continuous phases, which are scCO₂ and compressed liquid DME, as a polymerization medium, the surfactant types and the concentration, initiator concentration, and monomer concentration on the morphology and size of the polymer particles was also investigated.     

Preparation of micron-sized, monodisperse poly(methyl methacrylate)/polystyrene composite particles having a large number of dents on their surfaces by seeded dispersion polymerization in the presence of decalin

Seeded dispersion polymerization of styrene with 1.77-µm-sized, monodisperse poly(methyl methacrylate) seed particles was carried out in a methanol/water medium (8/2, w/w) in the presence of decalin droplets. The monodisperse poly(methyl methacrylate)/polystyrene composite particles produced had a large number of dents on their surfaces. The effects of the amount of decalin in the polymerization system on the number, the diameter, and the depth of the dents on the surface of the composite particles were clarified.     

核／壳结构聚丙烯酸酯塑料增韧剂的制备与结构控制

核／壳结构聚丙烯酸酯塑料增韧剂的制备与结构控制张会轩戴英杨海东＊冯之榴（吉林工学院化工系长春１３００１２）（中国科学院长春应用化学研究所１３００２２）关键词聚丙烯酸酯，增韧剂，制备，种子乳液聚合１９９６－０８－２８收稿，１９９７－０１－０６修回国家自...     

Influence of the third monomer on lauryl methacrylate–methyl methacrylate emulsion terpolymerization

An experimental study shows how the emulsion terpolymerization of lauryl methacrylate (LMA) and methyl methacrylate is influenced by the nature of the third monomer. The third monomer is either glycidyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, or styrene. We report the synthesis of terpolymer particles with an appreciably high content of the very hydrophobic LMA (between 0.2515 and 0.238 molar fraction in the monomer mixture) in 60:40 weight water/ethanol mixture as the continuous phase, poly(vinyl pyrrolidone) as a polymeric steric stabilizer, and potassium peroxodisulfate as the initiator. The emulsion terpolymerization proceeds smoothly without the formation of coagulum and leads to particles with an average diameter clearly below 1 μm. We discuss the overall polymerization behavior regarding conversion–time curves, particle morphology, and glass transition temperature of the terpolymers in dependence of the lyophilicity/lyophobicity of the monomer mixture.     

METHODS TO DETERMINE CRYSTAL LATTICE PARAMETERS OF OPAL-LIKE STRUCTURES

Journal of Structural Chemistry - Series of high-quality spherical poly(methyl methacrylate) particles with a polydispersity less than 5% are prepared by chain-growth emulsifier-free controlled...     

Graft polymers from poly(vinyl chloride) and chlorinated rubber

Graft polymers from poly(vinyl chloride) (PVC) and chlorinated rubber (CIR) with side chains of poly(methyl methacrylate) (PMMA), poly(methyl acrylate) (PMA), or poly(ethyl methacrylate) (PEMA) were synthesized. For this purpose, a vinyl monomer was polymerized in the presence of small quantities of PVC or CIR with benzoyl peroxide as catalyst. The graft polymers were separated from both homopolymers by precipitation with methanol from methyl ethyl ketone solutions of the reaction products and the grafting efficiency was calculated. The graft polymers were characterized by infrared spectra, elemental analysis, NMR, and osmometric or light-scattering determinations. From the results it is concluded that the PVC or CIR molecules contain side chains of PMMA, PMA, or PEMA. The graft polymers showed higher molecular weights, and the values of second virial coefficient for these polymers were much different from those of the starting polymers.     

Dispersion polymerization of MMA in supercritical CO2 stabilized by random copolymers of 1H,1H–perfluorooctyl methacrylate and 2‐(dimethylaminoethyl methacrylate)

A series of random copolymers, composed of 1H,1H‐perfluorooctyl methacrylate (FOMA) and 2‐dimethylaminoethyl methacrylate (DMAEMA) were prepared as stabilizers for the dispersion polymerization of methyl methacrylate in supercritical CO₂ (scCO₂). Free‐flowing, spherical poly(methyl methacrylate) (PMMA) particles were produced in high yield by the effective stabilization of poly(FOMA‐co‐DMAEMA) containing 34–67 w/w % (15–41 m/m %) FOMA structural units. Less stabilized but micron‐sized discrete particles could be obtained even with 25 w/w % (10 m/m %) FOMA stabilizer. The result showed that the composition of copolymeric stabilizers had a dramatic effect on the size and morphology of PMMA. The particle size was controllable with the surfactant concentration. The effect of the monomer concentration and the initial pressure on the polymerization was also investigated. The dry polymer powder obtained from dispersion polymerization could be redispersed to form stable aqueous latexes in an acidic buffered solution (pH = 2.1) by an electrostatic stabilization mechanism due to the ionization of DMAEMA units in the stabilizer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1365–1375, 2008     

Non-bioaccumulative, environmentally preferable stabilizer architectures for the dispersion polymerization of MMA in supercritical CO2

To overcome the environmental concerns associated with long-chain perfluorinated compounds, in this report, non-bioaccumulative, environmentally friendly stabilizer architectures based on short-chain fluorinated polymers have been designed for the dispersion polymerization of methyl methacrylate (MMA) in supercritical CO₂. Random copolymers composed of 2-(diisopropylamino)ethyl methacrylate (DPAEMA) and 2,2,3,3,4,4,4-heptafluorobutyl methacrylate (FBMA) or 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate were prepared with various comonomer ratios and utilized as stabilizers. It was found that the copolymers effectively stabilized PMMA latexes in CO₂, leading to the formation of free-flowing, spherical PMMA particles. With increase in the concentration of the stabilizer poly(FBMA-co-DPAEMA) from 2% to 6% (w/w with respected to MMA), the particles diameter decreased from 3.02 to 1.0 μm.     

Brush-type amphiphilic diblock copolymers from "living"/controlled radical polymerizations and their aggregation behavior

Two brush-type amphiphilic diblock copolymers, poly(poly(ethylene glycol)methyl ether methacrylate-block-polystyrene) (P(PEGMA)-b-PS) and poly(glycidyl methacrylate)-block-poly(poly(ethylene glycol)methyl ether methacrylate) (P(GMA)-b-P(PEGMA)) were synthesized, respectively, via consecutive atom-transfer radical polymerizations (ATRPs) and reversible addition-fragmentation chain-transfer (RAFT) polymerizations. The diblock copolymers were characterized by gel permeation chromatography (GPC), (1)H nuclear magnetic resonance (NMR) spectroscopy, and FT-IR spectroscopy. The aggregation behavior of the two amphiphilic diblock copolymers in water was also studied. Scanning electron and transmission electron microscopic images revealed that spherical micelles (40-80 nm in diameter) from self-assembly of the P(PEGMA)-b-PS copolymers and wormlike micelles (60-120 nm in length and 20-30 nm in diameter) from self-assembly of the P(GMA)-b-P(PEGMA) copolymers were prevalent. The spherical P(PEGMA)-b-PS micelles could self-assemble gradually into giant aggregates of several micrometers in diameter.