Influence of unsaturated acid monomer on the morphology of latex particles in the preparation of hollow latex via the alkali post‐treatment

Abstract

Multistage hydrophilic core/hydrophobic shell latexes containing carboxyl groups were prepared via multistep seeded emulsion copolymerization, and particles with different morphologies were obtained after alkali post-treatment. Influences of the type and content of unsaturated acid monomer on the polymerization and the particle morphology were investigated based on conductometric titration and TEM observation. Results showed that the hydrophilic core/hydrophobic shell particles could be easily formed using methacrylic acid (MAA) instead of acrylic acid. When MAA was 12.2 wt % in the core latex preparation, only fine pores existed inside the alkali-treated particles. With MAA increased from 20.0 to 30.0 wt %, the alkali-treated particle morphology evolved from porous, hollow to collapse structure. When MAA further increased to 40.0 wt %, it was difficult to prepare uniform multistage particles and distinct morphologies including solid, deficient swelling, hollow and collapse structure were coexistent in the alkali-treated particles. Moreover, the forming mechanism of different morphologies was proposed.

Facile fabrication of snowman-like Janus particles with asymmetric fluorescent properties via seeded emulsion polymerization

“…The formation of hollow microspheres may be due to the water stirred into the interior of RNP-2 in the presence of abundant SDS. And these small water pools inside the seed particles may coalesce to minimize the free energy during the swelling process and polymerization, resulting in the existence of one or two cavities inside particles finally [53][54][55].…”

Preparation and characterization of cationic pH-sensitive SiO2/polymer core-shell nanoparticles with amino groups in the shell

“…The distribution of amino groups in the core-shell latex was determined by conductometric titration at 25°C as follows [30,31]: 3 g of the original latex particles was diluted with 30 g of water, and the solid content was measured by a gravimetric method. The pH value of the diluted latex particles was first adjusted to 11.0±0.02 using a 0.1 mol/l NaOH aqueous solution, and the latex particles were then titrated with a 0.04 mol/l H 2 SO 4 aqueous solution; the particles' conductivity (κ) was recorded using a DDS-307 conductometer (Leici, Shanghai, China).…”

Fabrication and morphology control of hollow polymer particles by altering core particle size

“…The distribution of carboxyl groups in the latex was determined by conductometric titration with the following procedure according to the literature [25]; 1.00 g of the original latex was diluted with 100 g of water, and its solid content was measured using a gravimetric method. The pH value of the diluted latex was first adjusted to 11.5±0.02 using 0.385 mol/l NaOH aqueous solution, then the latex was titrated with 0.102 mol/l H 2 SO 4 aqueous solution, and its conductance (σ) was recorded using a DDS-307 conductometer (Leici, Shanghai, China).…”

“…Recently, we have been engaged in the preparation of hollow polymer latex particles and the control of particle morphology from synthesizing multistage hydrophilic core/hydrophobic shell latex particles and performing alkali posttreatment based on the osmotic swelling principle, and some valuable results were obtained [24,25]. In this article, with the aim of controlling the morphology of hollow polymer particles and discussing the relationship between particle size and morphology, core particles with different sizes were first synthesized under a very low concentration of surfactant, then the influences of core particle size on the emulsion polymerization and the formation of hollow morphology were investigated, and the forming mechanism of different particle morphologies was proposed according to the experiment results and analysis.…”