Nano‐SiO2/PMMA‐PU composite particles with core‐shell structure via emulsion polymerization and their application in epoxy resin

A novel method of nano‐SiO₂/poly(methyl methacrylate)(PMMA)‐polyurethane(PU) composite particles modifying epoxy resin is reported. The composite particles with the obvious core‐shell structure were prepared by emulsion polymerization of PMMA and PU prepolymer on the surface of nano‐SiO₂. The diameter of the composite particles was 50–100 nm with dark core SiO₂ (30–60 nm) and light shell polymer of PMMA and PU (20–30 nm); moreover, PU was well distributed in PMMA with about 10 nm diameter. After nano‐SiO₂ was encapsulated by PMMA and PU, the Si content on the surface decreased rapidly to 2.08% and the N content introduced by PU was about 1.27%. The ratio of polymer to original nano‐SiO₂ (f_p), the grafting ratio of polymer to original nano‐SiO₂ (f_r) and the efficiency grafting ratio of polymer (f_e) were, respectively, about 116.7%, 104.4%, and 89.5%. The as‐prepared composite particles were an effective toughness agent to modify epoxy resin, and the impact strength of the modified epoxy resin increased to 46.64 kJ m^?2 from 19.12 kJ m^?2 of the neat epoxy resin. This research may enrich the field of inorganic nanoparticles with important advances toward the modification for polymer composite materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41919.     

Preparation and properties of core–shell nanosilica/poly(methyl methacrylate–butyl acrylate–2,2,2‐trifluoroethyl methacrylate) latex

A core–shell nanosilica (nano‐SiO₂)/fluorinated acrylic copolymer latex, where nano‐SiO₂ served as the core and a copolymer of butyl acrylate, methyl methacrylate, and 2,2,2‐trifluoroethyl methacrylate (TFEMA) served as the shell, was synthesized in this study by seed emulsion polymerization. The compatibility between the core and shell was enhanced by the introduction of vinyl trimethoxysilane on the surface of nano‐SiO₂. The morphology and particle size of the nano‐SiO₂/poly(methyl methacrylate–butyl acrylate–2,2,2‐trifluoroethyl methacrylate) [P(MMA–BA–TFEMA)] core–shell latex were characterized by transmission electron microscopy. The properties and surface energy of films formed by the nano‐SiO₂/P(MMA–BA–TFEMA) latex were analyzed by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, and static contact angle measurement. The analyzed results indicate that the nano‐SiO₂/P(MMA–BA–TFEMA) latex presented uniform spherical core–shell particles about 45 nm in diameter. Favorable characteristics in the latex film and the lowest surface energy were obtained with 30 wt % TFEMA; this was due to the optimal migration of fluorine to the surface during film formation. The mechanical properties of the films were significantly improved by 1.0–1.5 wt % modified nano‐SiO₂. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Properties of PHMS‐g‐p [butylacrylate (BA)‐N‐hydroxyl‐methyl acrylamide (NMA)] graft copolymer emulsions

Emulsion graft copolymerization of poly(hydrogenmethylsiloxane) (PHMS) and butyl acrylate (BA) in the presence of functional comonomer N‐hydroxyl‐methyl acrylamide (NMA) was conducted by batch emulsion copolymerization to modify the properties of polysiloxane. Morphology of graft copolymer particles was characterized by transmission electron microscopy. The effect of polymerization method, PHMS content, initiator concentration, and NMA content on stability of emulsion, morphology, size of particle, and rheological properties were investigated. It has been found that stability of emulsion is better by semicontinuous emulsion polymerization than that of batch emulsion polymerization and it increased with increasing PHMS‐NMA concentration. Increasing PHMS concentration and NMA concentration, the particle size and the viscosities increase. The property of resistance to electrolytes of graft copolymer emulsions and swelling property of film were also discussed. Results showed PHMS‐g‐P [butylacrylate (BA)‐N‐hydroxyl‐methyl acrylamide (NMA)] graft copolymer emulsion has good resistance to electrolytes and the water absorption of its film increases with increasing BA‐NMA content grafted onto PHMS. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2209–2217, 1999     

The effect of octamethylcyclotetrasiloxane (D4) addition on the structure and properties of film‐forming polyacrylate/silica core–shell composite particles

The film‐forming polyacrylate/silica core–shell nanocomposite particles with octamethylcyclotetrasiloxane (D₄) were successfully synthesized via aqueous emulsion polymerization in the presence of a glycerol‐functionalized nano silica sol. The ring‐opening polymerization of D₄ and the reaction with the glycerol‐functionalized nano silica particles before emulsion polymerization was the key procedure in this process. Transmission electron microscopy results showed that more nano silica particles tended to coat on the polyacrylate particles surface after the nano silica sols were modified with D₄. The silica aggregation efficiency was increased from 90.9 to 98.6% when the amount of D₄ used in the system was varied from 0 to 8.0 wt %. The transparency of the nanocomposite films was not compromised after D₄ was incorporated into the system. The films of the nanocomposite particles with or without D₄ both exhibited superior abrasive resistance. Furthermore, the water resistance and hydrophobicity of the films of these particles with D₄ were also improved significantly. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42003.     

Preparation and performance of nano‐SiO2 stabilized Pickering emulsion type sizing agent for glass fiber

The nano‐SiO₂ particles modified by silane coupling agent A‐1100 were used for preparing the vinyl ester resin (VE) Pickering emulsion. The stable emulsion could be served as the film former of sizing agent for glass fiber (GF). The influence of the wettability and the addition amount of nano‐SiO₂ on the stability of film former emulsion was explored. The effect of nano‐SiO₂ Pickering emulsion type sizing agent on the properties of GF was investigated. SEM images show that there existed a layer of sizing agent film with nano‐SiO₂ particles evenly on the GF surface. The abrasion resistance of the sized GF reached 3,579 times and the stiffness was 69 mm. The strand integrity also performed well. The fracture strength of GF bundles treated by Pickering emulsion type sizing agent increased by 28.6% to 0.504 N/Tex compared with that of the unsized GF bundles. The interlaminar shear strength (ILSS) of GF/VE composites sized by self‐made sizing agent which contained nano‐SiO₂ has improved, compared to the unsized GF reinforced VE composite. POLYM. COMPOS., 37:334–341, 2016. © 2014 Society of Plastics Engineers     

Effect of nano‐SiO2 on granule characteristic and fusion process of Poly(vinyl chloride‐co‐vinyl acetate)/nano‐SiO2 composite resin

Poly(vinyl chloride‐co‐vinyl acetate) (PVVA)/nano‐SiO₂ composite resin was prepared by radical suspension polymerization of the monomers in the presence of fumed nano‐SiO₂ particles premodified with γ‐methylacryloxypropyl trimethoxysilane. The cool dioctyl phthalate absorption percentage, granule porosity, and specific surface area of the composite resin were enhanced through incorporation of nano‐SiO₂ into the PVVA. Scanning electron microscope pictures showed the resin had higher porosity. PVVA/nano‐SiO₂ composite resin was mixed with pure PVC resin to form a mixture sample (polymer‐composite blend [PCB]) and the mixture was fused in the torque rheometer. The rheological test results indicated that, at a certain nano‐SiO₂ content, the fusion speed of PCB was accelerated and the fusion temperature of PCB was decreased, owing to nano‐SiO₂ dispersed evenly in the polymer matrix. When excessive nano‐SiO₂ was loaded, the fusion torque, the fusion time, and the fusion temperature of PCB were all increased. These properties are correlative to the dispersive density of nano‐SiO₂ in the polymer matrix. This study also demonstrated that the introduction of small amounts of nano‐SiO₂ into the resin increased the impact strength and tensile strength of PCB simultaneously. J. VINYL ADDIT. TECHNOL., 20:230–236, 2014. © 2014 Society of Plastics Engineers     

Preparation of soap‐free cationic emulsion using polymerizable surfactant

A kind of polymerizable surfactant, methacryloyloxyethylhexadecyldimethylammonium bromide (DMHB) was used to synthesis soap‐free cationic emulsion with styrene (St), methyl methacrylate (MMA), and methacryloyloxyethyltrimethylammonium chloride (MATMAC) by emulsion polymerization using 2,2′‐azobis(isobutylamidine hydrochloride) (AIBA) as a cationic initiator. The effects of polymerizable surfactant concentration, initiator concentration, and reaction temperature on the conversion of monomer were investigated. The results indicated that the rate of polymerization could be expressed as R_p = k_p[AIBA]^0.42[DMHB]^0.45 and the apparent activation energy (E_a) was 83.42 kJ/mol. The particle size, ζ potential, and apparent charge density of cationic latices were also measured. The average diameter of copolymer particles decreased with increasing DMHB, MATMAC, and AIBA content; the charge properties of the particles were decided by the DMHB, MATMAC, and AIBA content. The polymerization mechanism is discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1111–1116, 2006     

Semicontinuous emulsion copolymerization of 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranose (3‐MDG) and butyl acrylate (BA). Monomer feed addition

New polymer colloids based on the saccharide monomer, using of 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐α‐D ‐glucofuranose (3‐MDG), were prepared by semicontinuous emulsion polymerization, a widely used industrial process. The copolymerization of 3‐MDG and butyl acrylate (BA), by the monomer‐addition technique, at 70°C, using sodium persulfate (Na₂S₂O₈) as an initiator, was investigated. The influence of some reaction parameters, such as the type and concentration of the surfactants as well as the monomer addition rate (R_m) on the polymerization rate (R_p), the colloidal properties, and the stability of the latexes, was studied. It was found that under starved‐feed conditions the polymerization rate and the particle size (D) increased with an increasing rate of monomer addition. The weight‐average molecular weight (M _w) also increased by enhancing R_m and a narrower molecular weight distribution was obtained. Furthermore, the type and the concentration of the surfactants strongly influenced the particle size and its distribution. The effect of the seed stage on the particle size and its distribution was also investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2091–2102, 2003     

Study of surface‐functionalized nano‐SiO2/polybenzoxazine composites

A series of the surface‐functionalized nano‐SiO₂/polybenzoxazine (PBOZ) composites was produced, and an attempt was made to improve the toughness of PBOZ material, without sacrificing other mechanical and thermal properties. A benzoxazine functional silane coupling agent was synthesized to modify the surface of nano‐SiO₂ particles, which were then mixed with benzoxazine monomers to produce the nano‐SiO₂‐PBOZ nanocomposites. The notched impact strength and the bending strength of the nano‐SiO₂‐PBOZ nanocomposites increase 40% and 50%, respectively, only with the addition of 3 wt % nano‐SiO₂. At the same load of nano‐SiO₂, the nano‐SiO₂‐PBOZ nanocomposites exhibit the highest storage modulus and glass‐transition temperature by dynamic viscoelastic analysis. Moreover, the thermal stability of the SiO₂/PBOZ nanocomposites was enhanced, as explored by the thermogravimetric analysis. The 5% weight loss temperatures increased with the nano‐SiO₂ content and were from 368°C (of the neat PBOZ) to 379°C or 405°C (of the neat PBOZ) to 426°C in air or nitrogen with additional 3 wt % nano‐SiO₂. The weight residue of the same nanocomposite was as high as 50% in nitrogen at 800°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of high nano‐SiO2 contents on properties of epoxy‐modified polybenzoxazine

High‐performance nanosilica composites based on epoxy‐modified polybenzoxazine matrices are developed. Chemorheological study of benzoxazine–epoxy resin mixtures reveals that processing window of the benzoxazine resin (BA‐a) is substantially broadened with an addition of the liquid epoxy. Glass transition temperature (T _g) of the BA‐a copolymerized with epoxy resin shows a synergistic behavior with a maximum T _g value (174°C) at the benzoxazine–epoxy mass ratio of 80:20. The copolymer at this composition is also used as a matrix for nano‐SiO₂ composites. A very low melt viscosity of the benzoxazine–epoxy mixtures promotes good processability with the maximum attainable nano‐SiO₂ loading up to 35 wt%. From scanning electron microscopy investigation, fracture surface of the 35 wt% nano‐SiO₂‐filled benzoxazine–epoxy composite reveals relatively homogeneous distribution of the nano‐SiO₂ in the copolymer with good particle wet‐out. In addition, very high reinforcing effect was also observed in such high content of the nano‐SiO₂, i.e., about 2.5 times in modulus improvement. This improvement is attributed to the strong bonding between the copolymer matrix and the nano‐SiO₂ through ether linkage as confirmed by Fourier‐transform infrared investigation. POLYM. COMPOS., 38:2261–2271, 2017. © 2015 Society of Plastics Engineers     

Kinetic investigations of acrylic–polyurethane composite latex

The effect of various reaction parameters on the rate of polymerization, R_p, and on the particle size and morphology of aqueous acrylic–polyurethane hybrid dispersions, prepared by semibatch emulsion polymerization, was investigated. The particles of polyurethane dispersion were used as seeds during the polymerization of acrylic component: methyl methacrylate (MMA), butyl acrylate (BA), and a mixture of MMA and BA with the ratio of 1:1. These emulsions were found to form structured polymer particles in aqueous media using scanning electron microscopy. The kinetics of the emulsion polymerization was studied on the basis of Wessling's model. The influence of emulsifier and initiator concentrations, including the monomer feed rates, R_m, on the rates of polymerization and on the properties of the resulting dispersions were studied. The number of particles and the particle size were also measured during the polymerization process. The final values were found to be independent of the concentration of the emulsifier, initiator and the monomer feed rate in monomer starved conditions. In the steady‐state conditions, during the seeded semibatch hybrid emulsion polymerization, the rate of polymerization and the monomer feed rate followed the Wessling relationship 1/R_p = 1/K + 1/R_m. The dispersions MMA/PU, BA/PU, and MMA/BA/PU have K values of 0.0441, 0.0419 and 0.0436 mol/min, respectively. The seeded BA/PU hybrid polymerization proceeded according to Smith‐Ewart Case I kinetics, while the MMA/PU hybrid emulsions demonstrate Case II of the Smith‐Ewart kinetic model. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2639–2649, 2002     

Role of nano‐size SiO2 additive on the thermal behavior of cyanoacrylate nanocomposite

Nowadays, solvent‐free, one‐part cyanoacrylate adhesive is widely used in medicine and dentistry. According to a literature survey done by the authors, there are few papers concentrated on the role of nano‐sized particles on the thermal behavior of cyanoacrylate glue. Thus the main goal of the current research focused on clarifying the role of nano‐sized SiO₂ on the thermal behavior of cyanoacrylate. Thermal behavior of all materials including cyanoacrylate and its nanocomposites was studied by using Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) methods. The results of DSC analysis showed that an increase in the amount of nano‐sized SiO₂ results in decreases in the duration of cyanoacrylate curing, energy release during polymerization, and incubation time of polymerization. Furthermore, the results of TGA tests illustrated that the weight loss of cyanoacrylate strongly depends on the contents of both caffeine and SiO₂. In fact, an increase in nano‐sized SiO₂ content increases the degradation temperature of cyanoacrylate. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

Resultant synergism in the shear resistance of acrylic pressure‐sensitive adhesives prepared by emulsion polymerization of n‐butyl acrylate/2‐ethyl hexyl acrylate/acrylic acid

Acrylic emulsion pressure‐sensitive adhesives (PSAs) were synthesized by the copolymerization of n‐butyl acrylate with various levels of 2‐ethyl hexyl acrylate (2EHA) and a small constant amount of acrylic acid. The effect of varying the n‐butyl acrylate/2EHA monomer composition on the kinetic behavior of the polymerization and the characteristics of the copolymers prepared in a batch process were investigated. The results showed that increasing the amount of 2EHA in the monomer caused the polymerization rate and the glass‐transition temperature of the acrylic copolymers to decrease. Increasing the amount of 2EHA caused the gel content of the copolymers to decrease, reaching a minimum at 50 wt %; thereafter, the gel content increased at higher 2EHA levels. For the acrylic emulsion, the peel‐fracture energy of the PSAs decreased as the amount of 2EHA in the monomer was increased up to 50 wt %. At higher 2EHA levels, the peel‐fracture energy was relatively constant. Interestingly, a synergistic effect of increased shear resistance at 25 wt % 2EHA was observed without a significant trade‐off in terms of the peel and tack properties. This behavior was attributed to a good interconnection between the microgels and the free polymer chains inside the contacting particles in the adhesive film. Cooperation between various levels of 2EHA in the copolymer structure simultaneously changed the crosslink molecular weight (M_c) of the microgels and the entanglement molecular weight (M_e) of the free chains in the adhesive network morphology. The adhesive performance of the PSAs was found to be correlated with their M_c/M_e values as the 2EHA proportion was varied. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Nano‐sio2‐reinforced ultraviolet‐curing materials for three‐dimensional printing

As an additive manufacturing technology, ultraviolet (UV)‐curing three‐dimensional printing, which requires the use of a photocurable resin, is increasingly being used to produce customized end‐user parts of many complex shapes. In this study, to improve the strength and ductility of printing materials, nano‐SiO₂‐reinforced photocurable resins were prepared by a planetary ball mill; then, the morphology, photochemistry, thermal property, and mechanical properties of the nanocomposites were investigated and characterized. Transmission electron microscopy analysis indicated that the modified nano‐SiO₂ was well dispersed in the photocurable resin. The glass‐transition temperature increased from 67.2°C for the unfilled resin to 71.7 and 80.1°C for nanocomposites with nano‐SiO₂ contents of 0.3 and 0.7 wt %, respectively. The tensile strength and impact strength were increased by 46.7 and 165.3% for nanocomposites with 0.3 wt % nano‐SiO₂. The flexural modulus of the nanocomposites increased from 1.7 to 8.0 GPa when 0.7 wt % nano‐SiO₂ was added to the photocurable resin; this appeared to originate from the relatively high level of dispersion and the intimate combination of the nano‐SiO₂ with the matrix. The investigation of the physical and chemical properties of such UV‐curing materials showed that the low filler concentration (<1 wt %) of nano‐SiO₂ did not affect the processability of the nanocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42307.     

The influence of interphase on nylon‐6/nano‐SiO2 composite materials obtained from in situ polymerization

Three commercially available silane, titanate and aluminate based coupling agents were used to pretreat nano‐SiO₂ for the preparation of nylon‐6/nano–SiO₂ composites via in situ polymerization. The interphases formed in different composite systems and their influence on material properties were investigated. Results indicated that the interfacial interactions differed between composite systems, whereas rigidity and toughness of composites were all improved by addition of pretreated silicas at an optimal content of 4.3 wt%. The presence of pretreated silicas did not have a distinct influence in the non‐isothermal crystallization behaviour of the nylon matrix. The composites containing pretreated silicas had slightly higher dynamic viscosities and superior storage moduli at high frequency, compared with neat nylon‐6. Copyright © 2003 Society of Chemical Industry     

Study on synthesis of polyurethane‐epoxy composite emulsion

The stable polyurethane‐epoxy composite emulsion with the epoxy‐amine oligomer (DEA‐EP) and the epoxy resin oligomer has been prepared by step‐growth polymerization and controlled crosslinking technique. The emulsion forming transparent films can be cured at room temperature with trimethylolpropane tris (1‐ethyleneimine) propionate (TMPTA‐AZ). The DEA‐EP structure and its reaction with urethane prepolymers were proved by Fourier transform infrared spectra (FTIR). The studies on particle size, the particle size distribution, viscosity, and the films' transmittance (Tr) indicated that both trimethylol propane (TMP) and DEA‐EP contributed to improving the resin blends' compatibility and reducing the viscosity. The epoxy resin content can increase up to 20.0 wt % (based on the total content of the polyurethane and epoxy resin) and the emulsion was still stable. The data from the tensile test experiments showed that with the epoxy content increasing, the tensile strength (σ_b) and Young's modulus were proportionately raised, but the elongation at break (ε_b) decreased. Tensile tests also revealed that introducing TMPTA‐AZ as an outside‐crosslinker can increase the tensile strength. By adding 0.3 wt % of TMPTA‐AZ, the ε_b reduced from 429% to 371% and the σ_b increased from 4.4 to 13.73 MPa; by adding 1.8 wt % of TMPTA‐AZ, ε_b of the film was 67% of ε_b of the film with 0.3 wt % of TMPTA‐AZ, but its σ_b was 24.77 MPa and 180% of σ_b of the film with 0.3 wt % of TMPTA‐AZ. The cured films possessed excellent water and toluene resistance: water uptake (48 h, 3.1%; degree of curing: 70%), toluene uptake (210 h, 8%. degree of curing: 70%). Better properties of the composite emulsion will confer it as a potential application in low volatile industrial coatings. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Isothermal emulsion polymerization of n‐butyl methacrylate with KPS and redox initiators: Kinetic study at different surfactant/initiator concentrations and reaction temperature

Thermal initiators, although widely used in emulsion polymerization, are limited to high reaction temperatures due to their high activation energy. Redox initiators have low activation energies indicating that emulsion polymerization could be conducted at lower temperatures to save energy. In the present study, a redox initiator system comprised of hydrogen peroxide (H₂O₂) and ascorbic acid (AA) in conjunction with a Fe²⁺ ion catalyst is compared with a potassium persulfate (KPS) thermal initiator in an emulsion polymerization system consisting of n‐butyl methacrylate (BMA), sodium lauryl sulfate (SLS) and water. The dependence of particle number on surfactant and initiator concentrations shows that redox‐ and KPS‐initiated systems both follow the Smith‐Ewart theory. However, the high radical flux generated from the redox initiator results in the formation of much smaller latex particles and higher reaction rate with lower molecular weights. Latex particle size and molecular weight could also be influenced by reaction temperature. By using redox initiator, small monodisperse particles (diameter < 50 nm) can be achieved without using a large amount of surfactant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43037.     

Toward an understanding of the role of water‐soluble oligomers in the emulsion polymerization of styrene–butadiene–acrylic acid. Function of carboxylic acid

In a further effort to understand the role of water‐soluble oligomers formed during the emulsion terpolymerization of styrene/butadiene/acrylic acid (St/Bu/AA), the reaction temperature, initiator concentration, and ionic strength were varied and the kinetics and resulting oligomers were characterized as a function of reaction time. The rate of polymerization (R_p) was observed to increase with increasing temperature and initiator concentration; the reasons for this vary. The increase in R_p with increasing initiator concentration is mainly attributed to the increase in the number of oligomeric radicals formed and, subsequently, the resulting number of particles (N_p). Increasing the temperature increases the water solubility of both monomers and polymers, which results in changes in the composition and molecular weight of the oligomeric radicals being formed. The primary reaction locus in the St/Bu/AA system was noted to shift to the aqueous phase after most of the styrene and butadiene had reacted, based on the unreacted AA profile. The role of water‐soluble oligomers (both oligomeric radicals and dead oligomers) during the emulsion polymerization of St/Bu with acrylic acid can be described by three periods: (1) particle generation and (2) before and (3) after the critical surface saturation concentration (CSSC) is reached during the particle growth period. The incorporation of AA monomer into the oligomer chains after the CSSC may cause destabilization of the latexes through a bridging flocculation mechanism. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1988–1999, 2003     

Properties of poly(n‐butyl methacrylate) prepared by reverse atom transfer radical polymerization in an aqueous dispersed system

Reverse atom transfer radical polymerization (ATRP) of n‐butyl methacrylate (BMA) in waterborne media using Cu(II) complexes with azo initiators (i.e., reverse ATRP) was conducted. The influence of several factors, such as surfactant, catalyst, and reaction time, on the stability of the emulsion, the particle size, the morphology of the emulsion particles, and the control of the polymerization was investigated. The results showed great differences between ATRP and conventional emulsion polymerization, especially the nucleation mechanism and the kinetics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1542–1547, 2003     

A new investigation with the salting‐out effect on emulsifier‐free emulsion polymerization of methyl methacrylate

The effects of the various salts onto the emulsifier‐free emulsion polymerization of methyl methacrylate (MMA) were investigated. It was found that the kind and amount of the salts were very effective on the polymerization even onto the polymeric products. It is known that the ionic strength of the electrolyte is effective for the polymerization. However, our investigation with the same ionic strength of different electrolyte produced the different effect on the polymerization. It was found that the Stokes radiuses of ions are very important for the reaction kinetics and type of the product. At the same electrolyte concentration, as increased Stokes radii of cation of salts that not react (the fragments of initiator, ions, etc.) in polymerization, polymerization rate and average molecular weight of polymer decreased, polymer particle diameter increased. In the case of Br^? and SO₄⁼ the anions of the salt are also demonstrated some unexpected reactions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2494–2500, 2007