Synthesis of core-shell microspheres with active hydroxyl groups by two-stage precipitation polymerization

• Published in: Polymer international Vol. 54; no. 1; pp. 168 - 174
• Main Authors: Bai, Feng, Yang, Xinlin, Zhao, Yuzeng, Huang, Wenqiang
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.01.2005; Wiley
• Subjects: Applied sciences; core-shell structure polymer; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; poly(hydroxyethyl methacylate); Polymerization; precipitation polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; second initiation; core-shell structure polymer; Benzene(divinyl) copolymer; Microsphere; Conversion rate; Benzene(divinyl) polymer; Hydroxyethyl methacrylate copolymer; Experimental study; Crosslinked copolymer; Heterogeneous polymerization; Structure processing relationship; Free radical polymerization; Morphology; Preparation; Crosslinked polymer; Monodispersed particle; poly(hydroxyethyl methacylate); Kinetics; Radical copolymerization; precipitation polymerization; second initiation; Successive reaction
• ISSN: 0959-8103; 1097-0126
• DOI: 10.1002/pi.1670

Monodisperse micrometer microspheres having active hydroxyl groups with a dense core and a lightly crosslinked functional shell were prepared by two‐stage precipitation polymerization in the absence of any stabilizer. Commercial divinylbenzene (DVB), containing 80 % of DVB was polymerized by precipitation in acetonitrile without any stabilizer as the first stage polymerization and used as the core. When the conversion of DVB was about 60 % in the first stage, hydroxyethyl methacrylate (HEMA) and azobisisobutyronitrile (AIBN) were introduced into the reaction system and copolymerized with unreacted DVB on the core surface to form a lightly crosslinked functional shell with hydroxyl groups formed on the surface during the second stage precipitation polymerization. Both the crosslinking degree and the thickness of the shell layer depend on HEMA loading. The kinetic study demonstrated that the conversion of HEMA increased slightly with increasing HEMA loading. Higher HEMA loading and AIBN concentration increased the reaction rate significantly and formed more soluble oligomers, which resulted in secondary initiation with high HEMA loading. The resulting core–shell polymer particles were characterized with scanning electron microscopy (SEM), and FTIR. Copyright © 2004 Society of Chemical Industry