Chinese Journal of Polymer Science

, Volume 31, Issue 2, pp 201–210 | Cite as

Effects of molecular weight on thermal responsive property of pegylated poly-l-glutamates

  • Shusheng Zhang
  • Chongyi Chen
  • Zhibo Li (李志波)


We investigated the ring opening polymerization (ROP) of di- and tri-ethylene glycol monomethyl ether functionalized L-glutamate N-carboxyanhydrides (NCAs) using hexamethyldisilazane (HMDS) as primary initiator and 1,5,7-triazabicyclo-[4.4.0]dec-5-ene (TBD) as co-initiator. The binary initiator system afforded a living ROP for these pegylated NCAs, and a series of homopolypeptides with controlled molecular weight (MW) and low polydispersity were obtained. We then systematically studied the helical content and clouding point (CP) dependence on polypeptide MW using circular dichroism (CD) spectroscopy and turbidity measurements, respectively. We found that the helical content of both homopolypeptides increased with MW, but the triethylene glycol functionalized poly-L-glutamate (poly-L-EG3Glu) intended to form more stable α-helical structure than diethylene glycol functionalized counterpart (poly-L-EG2Glu) at similar MW. Accordingly, the CP of poly-L-EG2Glu with known end group has strong dependence on its helical content, which is essentially determined by MW. Our results suggested that the thermal responsive properties of these unique pegylated poly-L-glutamates not only rely on their chemical structure but also on their secondary structures, which is different from conventional thermal responsive polymers.


N-carboxyanhydride (NCA) Ring opening polymerization Polypeptide Helicity Thermal responsive 


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Copyright information

© Chinese Chemical Society, Institute of Chemistry, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Shusheng Zhang
    • 1
  • Chongyi Chen
    • 1
  • Zhibo Li (李志波)
    • 1
  1. 1.Laboratory of Polymer Physics and Chemistry, Institute of ChemistryChinese Academy of SciencesBeijingChina

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