The Controllable Preparation And Characteirzation Of Functional Microspheres

The functional microspheres have been the favourite things since the study started. Itusually refers to the micro-and nano-particles with some specific functions. According to thedifference of the composition, they can have different performance, such as catalyticproperties, optical properties, adsorption properties and magnetic properties, being responsiveto temperature and pH and so on. According to their morphology, functional particles can bebroadly classified as follows: solid microspheres, hollow microspheres, porous microspheres.Since the emergence of functional particles, they’ve been grabbing countless eyeballs by thereason of their outstanding performance, and also their preparation strategies and propertiesresearch emerging in endlessly.From the perspective of low carbon, energy-green, this article explored a newcontrollable method to prepare the functional composite microspheres and functional hollowmicrospheres. Recently, we have reported a novel thermodynamic effect, for it’s so ordinarythat once was neglected, however, it could be used purposely to drive and control the basecore microspheres and shell material particles, so that the shell material coated on thesubstrate surface of the microspheres to form a different core-shell structure. This strangephenomenon occurred on the basis of colloids thermodynamics that minimization of Gibbsfree energy of the colloidal system. It’s worth noting that this method did not rely on physicalor chemical action between the shell material and the substrate microspheres, therefore, thepreprocessed functional modification of the substrate surface of the microspheres was notnecessary. On this basis, this paper made a further exploration from the following two majoraspects:Firstly, a facile and controllable heterocoagulation between polystyrene (PS)microspheres and multi-walled carbon nanotubes (MWCNTs) was introduced based oncolloid thermodynamics. The MWCNTs played the role of stabilizer for stabilizing themetastable PS microspheres and thus immobilized spontaneously on the surface of PSmicrospheres. The synthesized MWCNTs-coated PS composite microspheres wereextensively characterized by scanning electron microscopy, transmission electron microscopy,thermogravimetry, and Raman spectroscopy. The results indicated that the structure andmorphology of the resultant MWCNTs-coated PS composite microspheres were significantlyaffected by the weight ratio of PS and MWNCTs and the amount of poly(vinylpyrrolidone)that was injected into PS dispersion before they were mixed with MWCNTs. With theincrease of the weight ratio of MWCNTs/PS, more and more MWCNTs attached densely andwrapped tightly on the surface of PS microspheres due to their flexibility, making the surfaceof PS microspheres increasingly rough. Moreover, some MWCNTs also served as joints between neighboring PS microspheres. When the weight ratio of MWCNTs/PS was higherthan1:4, the MWCNTs either connected to one another or nested one on top of another toform an interdigitated over layer. The PVP was preferred, namely that, the flexible polymerwas more powerful and efficient than the nano-size object as stabilizer. Heterocoagulationonly occurred and maintained when the PVP was insufficient. As enough PVP was addedbefore blending the PS dispersion with MWCNTs, there was obviously no need for theadsorption of extra MWCNTs onto the surface of PS microspheres. Hence, we could concludethat this synthetic strategy distinctly had the flexibility and controllability based on colloidthermodynamics.Secondly, hollow monodispersity chitosan microspheres were prepared on the basis ofthis effect. In this current article, CS could self-assemble with raw PS template microspheresbased on a unique thermodynamically driving effect, then CS hollow microspheres wereobtained readily by cross-linking of CS on the surface of template microspheres and removedthe core template subsequently. The synthesized CS hollow microspheres were extensivelycharacterized by scanning electron microscopy, transmission electron microscopy, and Fouriertransform infrared spectroscopy. Finally, with the CS hollow microspheres as the slow-releasecarrier, we studied its slow-release effect on TDSA. The results indicated that the morphologyof resultant CS hollow microspheres could be controlled by changing the cross-linking time,the partical size of the template and the concentration of acetic acid; as for the CS-TDSAcapsule, the load rate of TDSA reached5.43%, the slow-release rate was40.7%at the former19hours.