| Abstract |
Well-defined temperature-responsive cellulose acetate (CA) grafted with a temperature-responsive polymer (TRP) was synthesized using a grafting-to approach. The TRP obtained by reversible addition-fragmentation chain transfer polymerization (RAFT), with M-n = 17 700 and dispersity D = 1.10, is a random copolymer of di(ethylene glycol) methyl ether methacrylate (MEO(2)MA) and oligo(ethylene glycol) methyl ether methacrylate (OEGMA), containing terminal azide groups introduced by addition of an azide-modified methacrylate monomer in the final stage of the polymerization. For the comonomer ratio used, the volume phase transition temperature of the TRP is T-VPT = 33 degrees C. After modification of CA with propargyl groups using the remaining hydroxyl groups of the glucopyranose rings, the TRP was grafted to the CA by an azide-propargyl click reaction. The CA-g-TRP copolymer was then used to prepare fibers by electrospinning, for application as temperature-responsive scaffolds in cell culture. The fibers were found to change their average diameter from 2.0 +/- 0.4 mu m to 1.3 +/- 0.3 mu m upon heating in water, above the T-VPT, and subsequently drying. When cooled in water below the T-VPT, the average diameter increases to 1.8 +/- 0.3 mu m. Experiments in thin films of the same copolymer show that the change in temperature does not translate into a significative change in the hydrophobic character, possibly due to a conformation rearrangement of the copolymer chains. |
