Synthesis Of Sheet-like Polystyrene Nano-material By Soft Template In Water Phase System

Because of good heat and mass transmission,emulsion polymerization in water phase system is suitable for fabricating polymer by free radical polymerization.In traditional emulsion polymerization,micelles of surfactant are global,and products are global polymer particles too.In spite of sphere,in water phase system surfactant micelles can be other morphology,such as sheet-like.Using sheet-like micelles as soft template, sheet-like polystyrene was obtained in our works.This method is also suitable for other polymer.This is a new synthesis of nano-materials,and it can enrich soft of polymer nano-materials.Moreover,it appears from these results that the sheet-like polymer possesses special internal structures.In our works,sodium dodecyl sulfate(SDS)micelles were researched in water phase system,and sheet-like micelles were found that they possess structure of SDS lamellar liquid crystal when they are solid.In our works,Polystyrene(PS)particles having nonspherical, sheet-like morphologies were synthesized in a heterogeneous system. Before reactants were introduced,a turbid system was primarily established at room temperature by adding potassium chloride(KCl)into a sodium dodecyl sulfate(SDS)-water system to change the morphology of surfactant self-assembly aggregations.Polymerization was carried out at 50℃by adding 0.008 g of initiator ammonium persulfate(APS)and 8 ml of freshly distilled St.The reaction was completed after 20 h,and the crude product was separated from the turbid system by a 2-fold filtration.Here, the precipitate was washed extensively with 50%methanol-water to remove the surfactant,the electrolyte and the residual monomer.Infrared (IR)and the atomic absorption spectroscopy(AAS)analyses were carried out to confirm the composition and structure of s-PS obtained from this system.TEM,SEM and AFM studies indicated that the polymer particles were about 2 nm thick,whereas their plane size was irregular.There were apparent differences in thermal behaviors between the sheet-like PS(s-PS) and the spherical PS obtained from the conventional emulsion system,viz.The DSC curve of s-PS demonstrated the glass transition at about 105℃and an exothermic peak near 154℃.We surmised that the fractal-like nanoparticles obtained from the heterogeneous system were made up of single chains that adopt intramacromolecular entanglement rather than interchain interpenetrating and entanglement.Moreover,in our works sheet-like polymethylmethacrylate(PMMA) was prepared by similar method.Line-like SDS micelles were also obtained by similar method,and line-like PS was prepared too.As whole,using surfactant micelles as template,sheet-like polymer can be obtained by free radical polymerization in water phase system.It would be significant in progress of polymer nano-science.