Thermo-responsive hydrogels based on branched block copolymers

The majority of thermo-responsive hydrogels currently investigated are based on amphiphilic polymers which give networks by the formation of physical crosslinks. Such physical crosslinks can be disrupted upon a change in temperature, which transfers the gel into a free flowing fluid, a sol. The transition of a gel to sol ideally is fully reversible. When this transition is close to body temperature these materials are potentially applicable as injectable systems for drug delivery and tissue engineering. Drugs or cells can be easily mixed into the free flowing sol, and upon injection into the body, the temperature change can cause a transition from sol to gel, forming a local drug or cell depot, in a minimally invasive manner. Preparing these hydrogels from biodegradable polymers offers the additional advantage that the hydrogels do not need to be explanted after their functional time, because the polymer will be degraded in the body, and the degradation products are excreted via natural pathways. This thesis describes a study on the preparation of thermo-responsive hydrogels from biodegradable copolymers with branched architectures.