title: Water Absorption Behavior of Polystyrene Particles Prepared by Emulsion Polymerization with Nonionic Emulsifiers and Innovative Easy Synthesis of Hollow Particles.
abstract: Submicrometer-sized raspberry-like polystyrene (PS) particles, which were prepared by emulsion polymerization with polyoxyethylene nonylphenyl ether nonionic emulsifier (Emulgen 910, HLB 12.2) and potassium persulfate initiator, contained 8.5 vol % (relative to the particle) of water and 5.5 wt % (relative to PS) of Emulgen 910 in the inside. The water absorption decreased the glass transition temperature of the PS particles dispersed in an aqueous medium. The wt % (relative to PS) of the incorporated Emulgen 910 increased with increasing initial Emulgen 910 concentration in the emulsion polymerization, but the wt % (relative to the total Emulgen 910 used) of the incorporated Emulgen 910 was constant at approximately 50% independent of the initial concentration. The vol % (relative to particle) of water increased to 46% by heat treatment at 90 °C for 24 h, which was based on further water absorption, and resulted in spherical hollow particles, where the amount of the incorporated Emulgen 910 remarkably decreased in a short treatment and then remained almost constant during the heat treatment. After another 24 h treatment, the percentage of nonhollow particles increased gradually, which was based on the escape of the water domain together with Emulgen 910 from the inside of the particles. On the other hand, spherical PS particles prepared by emulsifier-free emulsion polymerization did not contain water in the inside and were not changed to hollow ones by a similar heat treatment. From these results, an innovative easy method to synthesize hydrophobic hollow PS particles is proposed.
authors.affiliation: Institute of Advanced Materials (IAM), Nanjing Tech University , 5 Xinmofan Road, Nanjing 210009, China.|Graduate School of Engineering, Kobe University , Kobe 657-8501, Japan.
authors.forename: Masayoshi
authors.identifier: 0000-0003-1189-572X
authors.initials: M
authors.lastname: Okubo
authors.affiliation: Graduate School of Engineering, Kobe University , Kobe 657-8501, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kobayashi
authors.affiliation: Institute of Advanced Materials (IAM), Nanjing Tech University , 5 Xinmofan Road, Nanjing 210009, China.
authors.forename: Chujuan
authors.initials: C
authors.lastname: Huang
authors.affiliation: Graduate School of Engineering, Kobe University , Kobe 657-8501, Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Miyanaga
authors.affiliation: Graduate School of Engineering, Kobe University , Kobe 657-8501, Japan.
authors.forename: Toyoko
authors.initials: T
authors.lastname: Suzuki