Study On Controllable Self-Assembly Of Ferrocene/Azobenzene Double-Tail Block Polymer

Amphiphilic polymers can self-assemble into nano-structure in solution,which can find applications in many fields such as nanotechnology,drug delivery,and template synthesis.Herein,we report the controlled self-assembly of a class of linear-dendritic amphiphilic polymers with different lenth of hydrophilic PEO block and Percec-type alkyl substituted benzoic acid mini dendrons containing ferrocene(Fc)and azobenzene(Azo)moieties(AzoFcPEO).The isomerization of Azo and redox of Fc moieties can respectively regulate the amphiphilicity of the polymer with different degrees.This works can offer tremendous possibilities not only for fundamental science of the controlled self-assembly but also for establishing a suitable method of regulating the nano-structures of amphiphilic polymers in aqueous solution.The main content and results of this paper are as follows under:A series amphiphilic block polymer with a ferrocene/azobenzene bitail alkyl chain and hydrophilic chain different in length.The molecular weight of the PEG hydrophilic chain includes 500,750,850,1000,1900.The products was characterized by nuclear magnetic resonance spectroscopy,infrared absorption spectroscopy and GPC.The multiple stimuli responsive self-assembly behavior of linear-dendritic amphiphilic polymers in aqueous was investigated by transmission electron microscopy(TEM)and dynamic light scattering(DLS).It has been proven that the extension of the nucleation segment,the repulsive force between the shell molecules,and the interfacial energy of the micelles are the three factors that change the morphology of micelles.Depending on the PEO molecular weight,polymer concentration and the applied stimuli,the extension of the nucleation segment,the repulsive force between the shell molecules,and the interfacial energy of the micelles will be changed,and these amphiphilic polymers in aqueous solution can self-assemble into various nano-structures,such as spherical micelles,worm-like micelles,vesicle,spherical compound micelles,rod-like compound micelles and vesicles.The effect of ferrocene oxidation on the change of micelle morphology is greater than the isomerization of azobenzene.When the hydrophilic chain is long,the micelles are spherical micelles with or without stimulation.When the hydrophilic-hydrophobic ratio is close to 1,there are mang micellar morphologys including worm-like micelles,spherical compound micelles,rod-like compound micelles and vesicles before and after UV light and oxidation.