Preparation And Properties Of Microporous Polymer Composite Microspheres

In recent years,organic microporous polymer materials have been widely used in adsorption,separation,hydrogen storage,catalysis and other fields due to their high specific surface area,high physical and chemical stability,and ease of functionalization,and have also become a research hotspot.In this paper,microspheres with micropore structure were synthesized by hyper-crosslinked knitting method.Methods for preparing composite microspheres by coating graphene oxide（GO）on the surfaces of microporous microspheres and loading AuNPs in micropores has been studied,and explored the application of composite microspheres in catalysis.In this paper,crosslinked microspheres were firstly synthesized through emulsifier-free emulsion polymerization with styrene（St）,divinylbenzene（DVB）and dimethyl diallyl ammonium chloride（DADMAC）as the monomers.Futhermore,microporous structure in the polymer microspheres were knitted via Friedel-Craft acylation’s reaction with 1,2-dichloroethane（DCE）as swelling agent,formaldehyde dimethyl acetal（FDA）as external crosslinker,and ferric trichloride（FeCl₃）as catalyst.Finally,graphene oxide/hyper-crosslinked microporous polymer microspheres（GO/HCMPs）were prepared via cladding GO to HCMPs by means of electrostatic interactions.Scanning electron microscopy,Zeta potential and particle size analysis results showed that the microporous microspheres were controlled at about 770 nm in size,with good monodispersity,and the surface of microspheres is positively charged,laid a good foundation for graphene coating.Nitrogen sorption isotherm and pore size distribution indicate that HCMPs combine massive micropores,and when the DVB content is 1%,the specific surface area reaches 902 m²/g.Transmission electron microscope（TEM）images,Raman spectra and X-ray photoelectron spectroscopy（XPS）show that GO sheets are successfully coated on the surface of HCMPs.In this paper,crosslinked microspheres were prepared by semi-continuous soap-free emulsion polymerization using St and DVB as monomers.Then,as described above the microporous structure was knitted by the Friedel-Crafts alkylation reaction to obtain microporous polymer microsphere.The obtained microporous polymer microspheres were used as a carrier,and the Au nanoparticles were loaded into the pores through thermal reduction to obtain AuNPs/HCMPs composite microspheres.The results of scanning electron microscopy and particle size analysis showed that the microspheres had good monodispersity.The results of nitrogen sorption isotherm and pore size distribution showed that the specific surface area and pore size of microporous polymer microspheres decreased with the increase of DVB content,and when the DVB content was 0.1%,the specific surface area is the largest,up to 1174.6 m²/g.After loading AuNPs,the specific surface area and the amount of micropores of the composite system decrease.When the amount of HAuCl₄ is 0.01 mM,the specific surface area of the composite system decreases to 206.9 m²/g,and the pore size distribution pattern approaches flat.SEM,X-ray diffraction（XRD）,and XPS analysis show that HAuCl₄ is successfully reduced to AuNPs.The use of the complex as a catalyst for the reduction of4-nitrophenol shows good catalytic performance.