PREPARATION OF STAR-SHAPED POLYMER WITH STEREOREGULAR POLY(METHYL METHACRYLATE) ARMS

ABSTRACT

Isotactic (it-) PMMA anions prepared with t-C₄H₉MgBr in toluene were reacted with ethylene glycol dimethacrylate (EGDMA) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to obtain a star shaped polymer. 1H NMR, SEC-LALLS and SEC-differential viscometric analyses of the polymer clearly indicated that the polymer is a highly branched star polymer with crosslinked dimethacrylate core; the number of arms was estimated to be 20–30. A similar reaction of syndiotactic (st-) PMMA anions formed with t-C₄H₉Li-(n-C₄H₉)₃Al in toluene with EGDMA was unsuccessful. However, the use of butane-1,4-diol dimethacrylate instead of EGDMA resulted in the effective formation of star polymers having st-PMMA arms; the number of arms was estimated to be 139. As a result, two types of star -shaped polymethacrylates with it- and st-PMMA arms were obtained.

Keywords:

• Star-shaped polymer
• Stereoregular polymer
• Anionic polymerization
• Dimethacrylate
• Methacrylate
• NMR
• SEC

ACKNOWLEDGMENTS

This work was partly supported by a Grant-in Aid for Scientific Research (No. 06651028) from the Ministry of Education, Science, Sports and Culture of Japan. The authors are grateful to Professor Takashi Norisuye and Dr. Yoh Nakamura of the Faculty of Science, Osaka University for their helpful advice on refractive index measurements.

Notes

Haddleton and his coworkers succeeded to obtain star PMMA with narrow molecular weight distribution by the reaction between PMMA living anion obtained by t-C₄H₉Li-(i-C₄H₉)₃Al and EGDMA in toluene at higher temperature (−10°C), but they did not mention about the stereoregularity.[14]