The synthesis of block copolymers based on polyethylene glycol (PEG) and polycaprolactone (PCL) is reported. PEG-b-PCL diblock copolymers were prepared using both enzymatic and tin-mediated ring-opening polymerisation. Well-defined PEG-b-PCL-b-PEG triblock copolymers were synthesised through coupling of PEG-b-PCL diblock copolymers using hexamethylene diisocyanate. In addition, a PEG-b-PCL diblock copolymer with a single vinyl group on the PEG-terminus was prepared and this was converted quantitatively into amine end-functional copolymers through the use of photo-initiated thiol–ene chemistry in the presence of cysteamine hydrochloride. The aggregation behaviour of diblock and triblock copolymers was investigated using a direct hydration technique. The majority of the polymers formed vesicles as expected from the block composition, with the diblock copolymers generally having significantly thicker membranes than triblock copolymers of comparable composition, indicating differences in the membrane microstructure. The inclusion of 10 wt% of a protonisable amine-functional diblock at neutral pH appeared to favor cylindrical micelle (worm) formation. This morphology appeared to be stable up to 100% amine-functional diblock copolymer, thus providing a facile route to prepare worm-like micelles with a well-defined number of functionalisable surface groups.
Bibliographical noteKAUST Repository Item: Exported on 2023-07-24
Acknowledgements: This work was part of an Industrial PhD project, which was co-funded by the Innovation Fund Denmark (Grant No. 9065-00202B) and Aquaporin A/S. The authors would like to acknowledge Klaus Qvortrup, Michael Johnson and Tillmann Pape at the Core Facility for Integrated Microscopy at the University of Copenhagen for providing help and support in obtaining Cryo-TEM images of the vesicle solutions.
ASJC Scopus subject areas
- Organic Chemistry
- Biomedical Engineering
- Polymers and Plastics