3D Confined Self-assembly Of Thermosensitive Diblock Copolymers

The self-assembly of block polymers is an important way to prepare polymer nanomaterials.Abundant morphologies are obtained by microscopic phase separation between the blocks.Self-assembled nanomaterials are widely used in micro reactors,catalyst carriers,and drug control release areas.In this paper,temperature sensitive block polymers polycaprolactone-b-poly?N-vinylcaprolactam??PCL-b-PNVCL?and polystyrene-b-poly?N-vinylcaprolactam??PS-b-PNVCL?were prepared.Then,three-dimensional?3D?soft-confined self-assembly was performed through the emulsion-solvent evaporation method,and the resulting self-assembled nanoparticles were studied for drug release and catalyst carriers.The main work is as follows:1.The PNVCL was synthesized by N-vinylcaprolactam?NVCL?through radical polymerization with the chain transfer agent HSCH₂CH₂OH and initiator 2,2'-azobis?2-methylpropionitrile??AIBN?.Under the catalyst of Sn?oct?₂,the hydroxyl terminal poly?N-vinylcaprolactam??PNVCL-OH?initiate the open ring reaction of caprolactone??-CL?.The block polymer PCL-b-PNVCL was confirmed by means of infrared-spectrum?IR?,ultraviolet-spectrum?UV?andgelpermeation chromatography?GPC?.The shuttle-type nanoparticles with size of about 470 nm long and 100 nm wide were obtained by 3D confined self-assembly through the emulsion-solvent evaporation method.PCL-b-PNVCL contained DOX drug through3D constrained self-assembly,its drug loading amount and drug loading rate were 3.2%and 5.8%,much larger than that of its micelles.The self-assembled nanoparticles has a sustained release effect when the temperature above 37?,and the release rate becomes faster at pH=5.It indicats that the self-assembled nanoparticles have potential as in the drug carrieres.2.The block polymer PS-b-PNVCL was prepared by reversible addition-fragmentation chain transfer polymerization.And its structure was confirmed by means of infrared-spectrum?IR?,ultraviolet-spectrum?UV?and gel permeation chromatography?GPC?.Block polymers was formed nanospheres with concave surfaces via emulsion-solvent evaporation method.The diameter of nanospheres is about 340 nm.The Au nanoparticles are in-situ composited with the coordination of PNVCL when the HAuCl₄·3H₂O and NaBH₄ were added.The degradation of methylene blue was catalyzed by PS-b-PNVCL/Au catalytic system,which proved the catalytic activity of the system.Nanospheres as a carrier for catalysts,improve the stability of Au nanoparticles,achieve catalyst separation via temperature responsiveness of block polymers,and thus the recycling of catalysts and green catalytic chemistry.