Suspension Polymerization of Styrene Monomer without Emulsifier and Initiator.

Abstract

Ultrasonic waves were used to perform suspension polymerization of styrene monomer in the absence of both emulsifier (surfactant) and polymerization initiator. Styrene monomer was ultrasonically dispersed as oil droplets at 40 kHz after being added dropwise into water. Polymerization of the monomer in the droplets was initiated with the radical species from water as the polymerization initiator generated by irradiation with a high frequency ultrasonic wave at 200 kHz on the surfactant-free (styrene monomer/water) emulsion. The particles thus prepared were confirmed to be polystyrene particles by FT-IR measurements and the particle size was found to be several tens nanometers through TEM observation and dynamic light scattering measurement.

Preparation of Oleic Acid/Water Emulsions in Surfactant-Free Condition by Sequential Processing Using Midsonic−Megasonic Waves

“…It is in contrast to a unimodal but wide size distribution which resulted from intense irradiation at low frequencies, such as in the range 0.05-2.65 µm in the presence of surfactant. 3 We suppose that the observed monodispersity of polymers synthesized at 200 kHz initiation with the present experimental setup 23 would be partly due to the monodispersed generation of monomer droplets by the submegasonic wave applied, in addition to the radical chain kinetics so far concerned. Consequently, high frequency or megasonic irradiation significantly contributed to the stabilization of oleic acid droplets over a short and long period.…”

“…The effect becomes more significant for smaller particulates and at higher frequencies, so that its application has widely been developed as precision or megasonic cleaning in semiconductor wafer manufacturings. − Meanwhile, megasonic waves as well as being a high power source at low frequencies are known to induce sonochemical effects including radical formation and molecular degradation, which have been used to open up a new field in sonochemistry, such as the sonolysis of methanol at 1 MHz, a new synthetic or degradation strategy of compounds, , etc. While ultrasonic initiation has also been developed for radical polymerization with high-power probes at 20 kHz in the pioneering studies, − submegasonic baths can give a more gentle condition for the initiation …”

“…While ultrasonic initiation has also been developed for radical polymerization with high-power probes at 20 kHz in the pioneering studies, [19][20][21][22] submegasonic baths can give a more gentle condition for the initiation. 23 We have paid attention to the acceleration effect of megasonic waves on SFE from a viewpoint of acoustic emulsification. As noted above, megasonic waves have characteristics different from those of kilohertz waves and their effects are significant for submicrometer particles.…”

Surfactant-free suspension polymerization of hydrophilic monomers with an oil-in-water system for the preparation of microparticles toward the selective isolation of tumor cells

“…As such, suspension polymerization with oil-in-water systems is less detrimental to the environment as it uses less organic solvent than inverse suspension polymerization. Okudaira et al reported a preparation method for hydrophobic polystyrene (PSt) microparticles by a surfactant-free suspension polymerization, 27 but there are no such reports on hydrophilic polymer microparticles, owing to the dissolution of hydrophilic monomers in water. Thus, it is challenging to establish a protocol toward hydrophilic polymer microparticles by surfactant-free suspension polymerization with an oil-in-water system.…”

Particle size and size distribution of styrene/sulfopropylmethacrylate/2,2′‐azobis[2‐methyl‐N‐(2‐hydroxyethyl) propionamide] (styrene/SPM/VA‐086) and styrene/N,N‐dimethyl‐N‐methacryloxyethyl‐N‐(3‐sulfopropyl) ammonium betain [styrene/SPE/oil‐soluble 1,1‐azo‐bis(cyclohexanecarbonitrile)]–initiated latices, using a zetasizer and atomic force microscopy

“…Using ultrasonic waves to perform suspension polymerization of styrene monomer in the absence of both emulsifier and initiator, Gen et al21 reported that the particle size obtained from TEM and dynamic light scattering was on the order of several tens of nanometers. Tuin and Stein22 investigated the adsorption of an ionic surfactant on polystyrene particles in the presence of a cosurfactant.…”