Reaction of methyl thioglycolate with chloromethylstyrene microgel: Preparation of core–shell-type microgel by chemical modification
✍ Scribed by Nobuhiro Kihara; Yukihiro Adachi; Kimitaka Nakao; Takashi Fukutomi
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 276 KB
- Volume
- 69
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
A uniform spherical polychloromethylstyrene (PCMS) microgel whose average diameter was 2.3 mm was prepared by dispersion copolymerization of chloromethylstyrene and divinylbenzene in ethanol-DMSO (25/3 v/v) in the presence of polyvinylpyrrolidinone. When the PCMS microgel was treated with an excess amount of methyl thioglycolate (MTG) in the presence of 1,8-diazabicylco[5.4.0]undec-7-ene (DBU) at room temperature in THF for 4 h, sulfenylated microgel was obtained. The introduction ratio of MTG corresponded well to the amount of DBU used. A transmission electron microscope (TEM) photograph and thermal analysis of the PCMS microgel partially modified by MTG showed that it had a core-shell structure, that is, an MTG-modified shell and an unchanged core. Since the reaction of the chloromethyl group and MTG was a diffusion-limited one, MTG was introduced into the PCMS microgel from the outer side layer by layer. The PCMS microgel in which 52% of the MTG was introduced was treated with an excess amount of pyridine in DMAc at 50ЊC for 48 h followed by acid-catalyzed hydrolysis in dioxane-water at 80ЊC for 48 h to give a zwitterionic microgel that formed a stable suspension.