Synthesis and thermal characterization of macromonomeric azo initiator containing poly(ε-caprolactone): Styrene and methyl methacrylate copolymerization
✍ Scribed by Mehmet S. Erogˇlu; Baki Hazer; Bahattin M. Baysal
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 345 KB
- Volume
- 68
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
Macromonomeric azo initiator containing biodegradable poly( 1-caprolactone, (PCL) was synthesized by the condensation reaction of PCL with 4,4 -azobis(4cyanopentanoyl chloride) and methacryloyl chloride. This macromonomeric azo initiator (MIM-PCL) was further used in the polymerization of styrene (St) or methylmethacrylate (MMA) via a radical initiated process at 60ЊC in bulk in order to obtain polystyrene (PS)-b-PCL or poly(methyl methacrylate) (PMMA)-b-PCL crosslinked block copolymers. Thermal decomposition kinetics of MIM-PCL and its copolymers were studied by using thermogravimetric analysis and differential scanning calorimetry (DSC). DSC traces of MIM-PCL showed two different exotherms, at 98 and 127ЊC. The first exotherm, observed at 98ЊC, was due to the polymerization of the terminal methacrylic groups; the other was due to the exothermic decomposition of azo groups of MIM-PCL. PCL-b-PS and PCL-b-PMMA crosslinked block copolymers showed single glass transition temperatures due to the compatibility of the crosslinked block segments. The polymer-solvent interaction parameter of PCL in chloroform was determined by vapor pressure osmometry to be 0.1 for the PCL-chloroform system at 30ЊC. The average molecular weights between junction points of crosslinked homo PCL were calculated by using the Flory-Rehner equation.