Block Copolymers of N-Vinyl Pyrrolidone with N-Hexyl Methacrylate and Stearyl Methacrylate. Synthesis, Characterization, Thermal Properties and Self-Assembly Behavior in Selective Solvents

Block copolymers of N-vinyl pyrrolidone, NVP and either n-hexyl methacrylate, HMA, PNVP-b-PHMA or stearyl methacrylate, SMA, PNVP-b-PSMA, were prepared by RAFT polymerization techniques and sequential addition of monomers starting from the polymerization of NVP and using two different CTAs. The synthesis of the copolymers was monitored by Size Exclusion Chromatography, SEC and NMR spectroscopy. The thermal properties of both types of copolymers were studied by Differential Scanning Calorimetry, DSC, Thermogravimetric Analysis, TGA and Differential Thermogravimetry, DTG. The self-assembly behavior in THF, which is a selective solvent for the polymethacrylates blocks, and in aqueous solutions, where PNVP is soluble was examined by static, SLS and dynamic light scattering, DLS, techniques. The effect of the side ester moiety of the polymethacrylate chain on the micellization behavior was traced. The hydrophobic compound curcumin was efficiently encapsulated within the micellar core of the supramolecular structures in aqueous solutions, as was demonstrated by UV-Vis spectroscopy.