Functional Block Copolymers And Self-assembly

The synthesis and assembling of the functionalized diblock copolymers have extensive applications for over several tens years.The combination of block copolyraers with drug pharmaceutic becomes closely integrated.Polymeric nano-scale micelles which lead to the targeted and prolonged releasing behavior especially for the drugs having a low stability and short half-life in vivo are extensively investigated.Application of polymeric micelles may offer new vision to effective bioactive compounds and promote their clinical applications.In this thesis,the classical method of living anionic ring-opening polymerization was investigated for the synthesis of diblock copolymer with the higher performance and narrower polydispersity index.In a selective solvent,the diblock copolymers could be self-assembled into core-sbell structure micelles by the hydrophobic and hydrophilic blocks,and provide theoretical basis for the application of biomedicine.1.Poly(N-vinyl-2-pyrrolidinone)(PVP) with nitrogen-containing group was by far the best known of its super-hydrophilic property and excellent biocompatibility,which has been proven to be extensively used in pharmaceutical industry.For macromolecular initiator,PVP chains terminated with hydrophobic group(PVPOH) were synthesized via free radical polymerization. Characterization results of FT-IR,~1H-NMR,and SEC confirmed the successful synthesis of PVPOH.2.The functionalized biodegradable and biocompatible amphiphilic copolymers were investigated as drug delivery system.By combining 2-mercaptoethanol with isopropyl alcohol as chain transfer agents,poly(N-vinyl-2-pyrrolidinone)-block-poly(D,L-lactide) P(VP-b-DLLA) having hydroxyl-end groups was synthesized by anionic polymerization.Characterization results of ~1HNMR,EA,and SEC confirmed the successful synthesis of P(VP-b-DLLA).Micellization behavior of P(VP-b-DLLA) in a selective solvent was characterized by dynamic light scattering,turbidity measurements,fluorescence probe technique,and transmission electron microscopy.These results suggested that the P(VP-b-DLLA) was a potential drug carrier in functionalized biodegradable and biocompatible drug delivery system.The potential of thermosensitive Poly(N-vinyl-2-pyrrolidinone)-block-poly(N-methylol-acrylamide) P(VP-b-NIPAM) micelles as drug delivery carriers have offers a prospect of new vision to keep themselves in the foreground,The functional monomer of NIPAM as a thermoresponsive block,combined with hydroxyl-terminated hydrophilic homopolymers of PVP was successfully synthesized into the thermosensitive copolyraer of P(VP-b-NIPAM) through an anion polymerization by using sodium naphthalene as initiator.Characterization results of ~1HNMR,EA, and SEC confirmed the successful synthesis of P(VP-b-NIPAM).The well-defined block copolymer can be self-assembled into micelles in aqueous solutions above LCST.Micellization behavior of P(VP-b-NIPAM) in aqueous solutions was characterized by dynamic light scattering,turbidity measurements,fluorescence probe technique,and transmission electron microscopy.The experimental results suggested that the P(VP-b-NIPAM) was a potential good drug carrier in a versatile and efficient nanoparticle drug delivery system,which allows localized,selective and targeted release responsive to external stimuli.