The Preparation Of Nanoparticles With Various Morphologies By Polymerizationinduced Self-assembly

Preparation of nanoparticles by Block copolymers self-assmebly has been a common approach.Compared with block copolymers traditional self-assem-bly,polymerization induced self-assembly(PISA)is an easier and more effi-cient process to fabricate polymer vesicles with various morphologies.This study was focus on preparation of nanoparticles with various morphologies and sizes by PISA.Effect of the conversion of acrylic acid,additives,structure of block copolymers and introducing acrylic acid to hydrophobic blocks on the morphology and size of final nanoparticles had been studied.(1)Poly(acrylic acid)-b-polystyrene(PAA-b-PSt)was synthesized by RAFT-mediated dispersion polymerization in ethanol/water mixed solvent,and spherical micelles,worms,vesicles and porous nanospheres were obtained.Firstly,the effect of the conversion of acrylic acid(AA)on the PISA process was studied,and porous nanoparticles with larger size and cavum had been ob-served.Subsequently,effect of polyvinyl porrolidone(PVP)with low molecular weight on the PISA process had been studied.When PVP was added to the polymerization system,the size and morphology of nanoparticles changed,and vesicles nanoparticles were observed.Finally,the effect of polyethylene glycol(PEG)with low molecular weight on the PISA process had been studied.When PEG with different molecular weight were added to the polymerization system,PEG 2000 showed the most effective regulation on the morphology of final na-noparticles.The reason is that the added PEG 2000 prevent the final nanoparti-cles from changing to porous,and vesicles nanoparticles were obtained finally.(2)AB diblock copolymers and ABA triblock copolymers were synthe-sized by momofunctional RAFT agent and bifunctional RAFT agent in in etha-nol/water mixed solvent,respectively.Effect of different block copolymer struc-ture on the PISA process had been studied.On account of different distribution of PAA on block copolymer chain,the solvation of block copolymers chain was changed,which led to different PISA behaviour.Larger vesicles nanoparticles almost without spherical nanoparticles were obtained in ABA triblock copoly-mer systems,which was different from AB diblock copolymer systems.Finally,effect of introducing AA to copolymerized with styrene(St)on the PISA process was also studied.Because of introduced AA,much larger size vesicles nanopar-ticles were obtained.Besides,large compound vesicles were also observed.