Enhancement of thermal stability of poly(divinylbenzene) microspheres

In order to enhance the thermal stability and prepare a new kind of carbon microbeads from poly(divinylbenzene) microspheres (PDM), air oxidation treatment was introduced to modify the pristine PDM. The results showed that the spherical shape of PDM was preserved via the air oxidation and further carbonization at 700 °C. The changes of morphology, especially the surface functional groups and the thermal properties of PDM after air oxidation were investigated in detail by SEM, IR and TG/DSC measurements, respectively. The possible mechanism of oxidation treatment was elucidated.     

Reassessing the Physicochemical Properties of Ordered Mesoporous Polymer and Copolymer Nanocasts

Nanocasting is a convenient way for preparing highly porous, nanostructured soft materials. Mesoporous polymer nanocasts have been reported for over a decade, however, several aspects remain to be explored further. To do so, we report a comprehensive investigation of the physicochemical characteristics of high surface area functional organic polymers and copolymers obtained by nanocasting. Divinylbenzene, styrene and chloromethyl styrene were selectively polymerized within the pores of mesoporous SBA-15 or KIT-6 silicas. Following template removal, the resulting materials were characterized. The nanocast mesoporous polymers were also modified to introduce functional groups. The success of the functionalization was assessed analytically and by model catalytic tests. The study points to the advantages of the hard templating method for structuring organic materials but also its limitations.     

The relationship between heterogeneous structures and phase separation in synthesis of uniform PolyDVB microspheres

Polydivinylbenzene microspheres from microvoids, hollow to different porous structures were respectively fabricated by a combined route of membrane emulsification and suspension polymerization. The relationship between these structures and the phase separation behaviors in formation of these microspheres was investigated by in-situ tracking phototransmittance of polymerization system. Macrospores or hollow structure formed by non-solvating porogen often induced fast decline of transmittance and early phase separation, while micropores formed by solvating porogen lead to much slower declines of transmittance and later phase separation. Besides, the gelling point of polymerization system during phase separation process was found crucial to influence movements of phases in polymerization and thus the final heterogeneity of microspheres. The later gelling point occurred, the more heterogeneous structures such as hollow or microvoids of microspheres formed, while the early gelling point facilitated fabrication of small pores or non-porous structure.