Synthesis of biodegradable pentaarmed star-block copolymers via an asymmetric BIS-TRIS core by combination of ROP and RAFT: From star architectures to double responsive micelles
✍ Scribed by Jianbo Li; Jie Ren; Yang Cao; Weizhong Yuan
- Book ID
- 104088184
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 992 KB
- Volume
- 51
- Category
- Article
- ISSN
- 0032-3861
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✦ Synopsis
Biodegradable star-shaped poly(3-caprolactone) and poly(3-caprolactone-b-L-lactide) (5sPCL-b-PLLA) with five arms were synthesized by ring-opening polymerization (ROP) from an asymmetric BIS-TRIS core via ''core-first'' strategy. Subsequently, a series of amphiphilic and double responsive star-block copolymers were synthesized by Z-RAFT star polymerization of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA) from the star-shaped macro-RAFT agent, which was prepared by attaching 3-benzylsulfanylthiocarbonylthiocarbonylsufanylpropionic acid (BSPA) to 5sPCL-b-PLLA using a simple two-step reaction sequence. GPC and 1 H NMR data demonstrated the polymerization courses are under control. The molecular weight of 5sPCL-b-PLLA-b-DMAEMA increased with the monomer conversion, and the molecular weight distribution was in the range of 1.19-1.37. The spherical micelles with degradable core and pH/thermo-double sensitive shell had been prepared from the aqueous medium of the amphiphilic star-shaped copolymers by dialysis method. Both pH and thermal-responsive behaviours of copolymer micelles obtained in this study were investigated. The micelle size and morphology were measured by DLS, AFM and TEM.