Loading…
Synthesis of Well-Defined Amphiphilic Poly(ε-caprolactone)-b-poly(N-vinylpyrrolidone) Block Copolymers via the Combination of ROP and Xanthate-Mediated RAFT Polymerization
Well-defined amphiphilic poly(ε-caprolactone)-b-poly(N-vinylpyrrolidone) (PCL-b-PNVP) block copolymers were successfully prepared via the combination of ring-opening polymerization (ROP) and xanthate-mediated reversible addition−fragmentation chain transfer (RAFT) polymerization. Well-defined poly(ε...
Saved in:
Published in: | Macromolecules 2011-04, Vol.44 (8), p.2465-2473 |
---|---|
Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | Well-defined amphiphilic poly(ε-caprolactone)-b-poly(N-vinylpyrrolidone) (PCL-b-PNVP) block copolymers were successfully prepared via the combination of ring-opening polymerization (ROP) and xanthate-mediated reversible addition−fragmentation chain transfer (RAFT) polymerization. Well-defined poly(ε-caprolactone) (PCL−OH) was synthesized by ROP in bulk at 110 °C using benzyl alcohol as initiator and stannous octate [Sn(Oct)2] as catalyst . The −OH end group was then converted into its corresponding xanthate (PCL−X) via the conversion to its corresponding bromide (PCL−Br). These are verified by 1H NMR spectroscopy. PCL-b-PNVP block copolymers were synthesized via RAFT polymerization in tetrahydrofuran (THF) at 80 °C using PCL−X as macro-chain transfer agent and characterized by 1H NMR spectroscopy and gel permeation chromatography (GPC). The amphiphilic diblock copolymer PCL63-b-PNVP90 forms spherical micelles of ∼34 nm diameter in water as shown by transmission electron microscopy (TEM), supported by 1H NMR spectroscopy, and light scattering. The critical micellar concentrations were determined by fluorescence spectroscopy using pyrene as probe. The critical micelle concentration (cmc) value of the block copolymers increases with the increase in the chain length of PNVP block. The overall hydrodynamic radius (R h) of the micelles remains almost constant over the concentration range above the cmc value and over the angles of scattering measurement. |
---|---|
ISSN: | 0024-9297 1520-5835 |
DOI: | 10.1021/ma102453h |