On the Size‐Determining Role of the Comonomer in the Nucleation and Growth of Cationic Polystyrene Latex via Emulsion Polymerization

Abstract

colloidal molecules. [10] As the polystyrene particle core can be easily removed by solvents or elevated temperatures, hollow metal oxide particles can be synthesized from polystyrene colloidal templates. [11,12] Finally, polystyrene colloidal particles have been extensively used in self-assembly processes to create ordered structures with high precision in two [13] and three dimensions. [14] Similar to the single particle level, such structures can serve as sacrificial templates to create arrays of surface nanostructures, [15] or nanoporous materials. [16] For all these applications of PS particles, control of particle size, polydispersity, and surface chemistry are of key importance. Hence, the development and understanding of reaction conditions leading to tailored and predictable size and surface functionality are crucial. Especially for small colloidal particle sizes with diameters below 100 nm, emulsion polymerization reactions often lead to high polydispersities, which can result from the short growth phase with decreasing monomer concentration and an incomplete separation of nucleation and growth. [17] Here, we focus on positively charged PS particles, which are commonly synthesized by emulsion polymerization with cationic initiators [11,18] or cationic comonomers. [19] Typically, such comonomers introduce charges via quaternary ammonium groups that can be used in styrene emulsion poly merizations with, [20] or without [17] additional surfactants. We use surfactant-free copolymerization of styrene and the quaternary ammonium salt (vinylbenzyl)trimethyl-ammonium chloride (VBTMAC) with 2,2-azobis (2-methylpropionamidine) dihydrochloride (AAPH) as initiator and investigate the role of the VBTMAC concentration on the resulting particle properties. We show that we can precisely control the particle size by the variation of VBTMAC concentration at three different styrene to water volume fractions. To clearly demonstrate the effect of VBTMAC on the particle size for each styrene volume fractions used control samples were synthesized without comonomer following a recipe similar to Nandiyanto et al. [11] We investigate the mechanistic origins of this control and the role of the monomer and comonomer in nucleation events and particle growths. We propose an PS particles growth mechanism which can be understood as an extension of the mechanism suggested by Liu et al. for a wide range of styrene to VBTMAC monomer ratios. [17] Importantly, our method enables the fabrication of highly Colloidal SynthesisThe formation of positively charged polystyrene latex particles via the surfactant-free emulsion polymerization of styrene with cationic initiator is investigated. Using the comonomer (vinylbenzyl)trimethyl-ammonium chloride (VBTMAC) it is shown that the particle size can be tuned rather precisely between above 350 nm and below 70 nm. The simple functional dependence of the particle size on the inverse cube root of the comonomer concentration leads to propose, with reasonable assumptions, that VBTMAC comonomer addition...

From Meso to Macro: Controlling Hierarchical Porosity in Supraparticle Powders

“…Next, we show how pores in the larger macropore regime can be introduced via binary mixtures of silica particles, which form the SP structure, and PS particles, which serve as templates for macropores. [26] We use surfactant-free emulsion polymerization [71,72] to synthesize these PS colloidal particles, mix them in a predefined size ratio with the silica PPs and spray-dry the mixture into composite SPs. The composition of these templated SPs closely mimics the initial composition, [14] which allows us to tailor the porosity after calcination (T = 1000 °C) to remove the PS templates (Figure 4a).…”

Surface Characteristics of Antibacterial Polystyrene Nanoparticles Synthesized Using Cationic Initiator and Comonomers

“…In this study, the cationic PSt nanoparticles were synthesized using (vinylbenzyl)­trimethylammonium chloride (VBTMAC) ,, and ADIP triflate as cationic comonomer and radical initiator, respectively. The structural properties exhibited by the polymer were characterized using transmission electron microscopy (TEM), and the cationic properties of the PSt nanoparticles was further characterized using an anionic fluorescent probe, 6-( p -toluidino)-2-naphthalenesulfonic acid sodium salt (TNS).…”

Synthesis of water-soluble ionic terpolymers by inverse microemulsion and solution polymerization methods

“…34 Although there are several articles on the synthesis of copolymers based on (vinylbenzyl)trimethylammonium chloride (VBTA), most of them are about latex preparation. [35][36][37][38] Unfortunately, the works describing the water-soluble synthesis of coor terpolymers based on VBTA are very scarce. 39,40 The incorporation of the ionic unit (in this case VBTA) to the structure of the water-soluble terpolymer promotes stability in a salt medium, while the incorporation of N-vinylpyrrolidone favors the thermal stability of the polymer, and the presence of acrylamide provides solubility in water and viscosity to the nal polymer solutions, for which the search for synthesis processes of ionic terpolymers with molecular weights greater than 0.5 Â 10 6 Da is very current.…”