Preparation Of Organic-Inorganic Composite Nanoparticles By Using Spherical Polyelectrolyte Brushes And Their Application

Organic-inorganic composite nanoparticles often show better thermal,mechanical,rheological,optical,and catalytic performance since they combine the properties of polymers with the unique functions of inorganic nanoparticles,which have been widely applied in many fileds,including medicine,agriculture,optics,semiconductor devices,aerospace and catalysis.Spherical polyelectrolyte brushes(SPB)can be used as ideal polymer carriers to generate or immobilize inorganic nanoparticles and effectively prevent the agglomeration of nanoparticles due to their unique core-shell structure,resulting in organic-inorganic composite nanoparticles with different functions and good stability.In this paper,two kinds of organic-inorganic composite nanoparticles were prepared by introducing specific inorganic nanoparticles to different spherical polyelectrolyte brushes respectively.One is to obtain the recyclable silver nanocatalyst by using magnetic spherical polyelectrolyte brushes(MSPB)as carriers,which consist of a core of polystyrene(PS)embedded with magnetic particles and shell of negatively charged poly(acrylic acid)s(PAA)brushes.Another one is to obtain the hollow silica nanoparticles(HSNP)by using cationic spherical polyelectrolyte brushes with a polystyrene(PS)core and poly(2-aminoethyl methacrylate hydrochloride)(PAEMH)brush shell as catalytic templates.The two composite nanoparticles were characterized by various characterization methods,including dynamic light scattering(DLS),transmission electron microscope(TEM)and thermogravimetric analysis(TGA),and their application was primarily explored.The main conclusions were as follows:The magnetic particles were directly embedded into the PS core,and the silver nanoparticles were mainly distributed on the PAA chains around the PS core.The obtained composite nanoparticles were narrowly dispersed,stable,rapidly responsive to the external magnetic fields,and redispersible.Ag nanoparticles with average diameter of 2.30±0.5 nm immobilized in the MSPB exhibited a high loading amount(about 75 mg/g).The reduction of 4-nitrophenol was used as a benchmark reaction to investigate the catalytic activity of composite nanoparticles.The results showed that the reaction rate accelerated with the increasing concentration of composite nanoparticles in the solution and the increasing temperature.The rate constant was 0.403 L/(s·m2)in 298K and the activation energy of the reaction was 66.03kJ/mol,which confirmed the high catalytic activity of composite nanoparticles for the reduction of 4-nitrophenol.The PS-PAEMH brushes were proved to be good catalytic templates for the formation of silica nanoparticles.The size of composite nanoparticles decreased with the reaction time until the end of the reaction while the thickness of silicon layer increased,resulting in the rough surface of the particles.The chain length of SPB and the thickness of silicon layer were adjusted by tuning the monomer feeding concentrations.Hollow spherical silica nanoparticles with uniform morphology,clear hollow structure and good stability were prepared by removing the PS core through solvent dissolving method.With doxorubicin hydrochloride(DOX)as the model drug,the drug-loading capacity of hollow silica nanoparticles was evaluated.The obtained hollow silica nanoparticles exhibited a high drug-encapsulation efficiency(80%)for DOX,which should be of significance in the fields of medicine and biology.