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- Title
Synthesis and characterization of dendritic starâshaped poly(εâcaprolactone)âblockâpoly(Lâlactide) block copolymers.
- Authors
Weian Zhang; Sixun Zheng; Qipeng Guo
- Abstract
Dendritic starâshaped poly(Éâcaprolactone)âblockâpoly(Lâlactide) (PCLâbâPLLA) diblock copolymers were synthesized via sequential ringâopening polymerization. In the first step, an aliphatic dendritic polyester containing 16 terminal hydroxyl groups was used as the core molecule to initiate the ringâopening polymerization of Éâcaprolactone, which was catalyzed by stannous(II) octanoate, to obtain dendritic starâshaped poly(Éâcaprolactone) (PCL) terminated with hydroxyls, which was used further to initiate the ringâopening polymerization of Lâlactide to form the dendritic starâshaped diblock copolymers. The dendritic starâshaped polymers (PCLâbâPLLA) were characterized with nuclear magnetic resonance spectroscopy and gel permeation chromatography. The results showed that the arm length of the dendritic starâshaped polymers could be well controlled in terms of the molar ratios of the initiators (i.e., the aliphatic dendritic polyester and starâshaped PCL) to the monomers (i.e., Éâcaprolactone and Lâlactide). The crystalline structure and thermal properties of the dendritic starâshaped polymers were investigated with Xâray diffraction and differential scanning calorimetry. The Xâray diffraction indicated that the formation of the dendritic starâshaped topological structure did not affect the structure of the crystals of PCL and poly(Lâlactide) (PLLA) blocks. The thermal analyses showed that the crystallization rate of the PCL blocks in the block copolymers was greatly reduced compared to that in the parent dendritic starâshaped PCL. This observation could be attributed to the confinement of the dendritic core and PLLA blocks upon the crystallization of the PCL blocks. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
- Subjects
DENDRITIC cells; BLOCK copolymers; SPECTRUM analysis; CHEMICAL reactions
- Publication
Journal of Applied Polymer Science, 2007, Vol 106, Issue 1, p417
- ISSN
0021-8995
- Publication type
Article
- DOI
10.1002/app.26484