Core-shell latex particles consisting of polysiloxane-poly(styrene-methyl methacrylate-acrylic acid): Preparation and pore generation

Abstract

Latexes with a poly(dimethyl siloxane) core and a poly(styrene-methyl methacrylate-acrylic acid) [poly(St-MMA-AA)] shell have been prepared in two steps in order to generate particles that have a core with a very low glass transition temperature. In the first step, poly(dimethyl siloxane) particles were obtained via the ringopening emulsion polymerization of octamethyl tetracyclosiloxane (D 4 ). The polymerization was carried out using either an anionic or a cationic catalyst. In the first case, sodium hydroxide was used as catalyst and sodium dodecylbenzene sulfonate as surfactant, while in the second, the alkylbenzene sulfonic acid (ABSA) was used both as catalyst and surfactant. Using a PD 4 latex as seed, a seeded emulsion polymerization of St-MMA-AA was conducted to obtain PD 4 -P(St-MMA-AA) core-shell particles. Numerous recipes were attempted and the most successful were those in which the seed was prepared with a cationic catalyst (ABSA) at a relatively low temperature (75°C). The core-shell structure of the particles was identified by transmission electron microscopy, but also via wetting angle, water absorption, and T g measurements. Finally, pores were generated in the core-shell particles via an alkali-acid treatment. Because PD 4 has a very low glass transition temperature, it cannot be easily handled. However, protected by a shell, it could be used as a constituent of composite materials with enhanced impact strength, even at very low temperatures.

Polymer heterogeneity in waterborne coatings

“…To obtain a sufficient level of mechanical performance, the PDMS polymer is covalently bonded to a polymer with a higher T g , for which purpose both polyacrylates and polyurethanes have been reported. 91 Direct polymerization of PDMS structures is most conveniently done through a mini-emulsion polymerization, optionally via a simultaneous anionic ringopening polymerization and a radical polymerization. 92 This avoids the need for diffusion of the hydrophobic PDMS precursor structures through the aqueous phase.…”

Polydimethylsiloxane latexes and copolymers by polymerization and polyaddition in miniemulsion

“…As PDMS has only a low mechanical performance by itself, the PDMS is usually blocked or grafted with polyacrylates/polystyrene, giving core-shell latexes [5][6][7]. Polyurethane-polydimethylsiloxane particles of diameters in the range 500 nm up to 5 mm, have been also recently synthesized by step-growth polymerization in cyclohexaneor supercritical carbon dioxide [8].…”

“…Polyurethane-polydimethylsiloxane particles of diameters in the range 500 nm up to 5 mm, have been also recently synthesized by step-growth polymerization in cyclohexaneor supercritical carbon dioxide [8]. For the generation of the PDMS from the monomer, both dispersion polycondensation of alkoxysilanes [5,9,10] as well as ring opening emulsion polymerization of the tetramer [7] have been employed. In the present context, it is important to note that the last reaction was also already performed in miniemulsions [11].…”

Core/Shell Particles Containing 3‐(Methacryloxypropyl)‐Trimethoxysilane in the Shell: Synthesis, Characterization, and Application

“…Presently polyacrylate (PA) is commonly considered for its good cohesiveness and excellent film‐forming property as compared with polysiloxane (PSi) 3,4. The combination of polysiloxane and polyacrylate has been shown to be important in the composite material field, especially as the core/shell particles 3,5…”