Dispersion copolymerization of polyoxyethylene macromonomer and styrene. Part 3. Molecular characterization of polystyrene-graft-polyoxyethylene copolymers

✍ Scribed by Capek, I.; Murgašová, R.; Berek, D.

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 226 KB
• Volume: 44
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(199710)44:2<174::aid-pi838>3.0.co;2-k

✦ Synopsis

Graft copolymers (polystyrene-graft-polyoxyethylene) (PS-graft-PEO) were prepared by the dispersion copolymerization of methacryloyl-terminated polyoxyethylene macromonomer and styrene initiated by an oil-soluble initiator (dibenzoyl peroxide, DBP). The apparent molecular weights of graft copolymers measured by size exclusion chromatography in tetrahydrofuran were found to be proportional to the [0É8th power of DBP concentration. This reaction order supports the termination of growing radicals by a Ðrst order radical loss process. The molecular weight distribution estimated from the size exclusion chromatography (SEC) data was found to decrease slightly with DBP concentration and to drop rapidly with macromonomer concentration. This was attributed to chain transfer events and to the increase of particle number : the higher the particle number the lower the monomer concentration in the particles. The bulkiness of the macromonomer molecules and the high segment density around the propagating reaction loci hinder the incorporation of macromonomer molecules into a copolymer growing chain.

Polym. Int. 44, 174È180 (1997) No. of Figures : 0. No. of Tables : 4. No. of References : 17 Key words : dispersion copolymerization, PEO