| Porous materials have ordered porous structure and high surface area,which are very important for application in many fields.Researchers have been paying more attentions to synthesize porous structural materials.Although many methods prepared porous materials have been used,employing microhydrogel to prepare porous materials scarcely reported in literatures.In this thesis two methods related to prepare porous microsphere have been proposed,and two examples for confirming the feasibility the methods proposed have been carried out.In order to prepare porous microspheres based on microhydrogels,solidification of polymeric networks in microgels is necessary.Herein, two protocols to enhance the rigidity of polymeric backbone were proposed.One is to introduce rigid monomer in polymerizition;another is to fill oxide in network of polymer in microgel.Based on the idea mentioned above,the research in this thesis includes the following two parts.(1) To enhance the rigidity of the polymeric chains in microgel,empolying rigid monomer NVP to synthesize microhydrogel P(AM-MAA-NVP) has been carried out.The morphology and structure of the polymer microgels were characterized by SEM,FT-IR,TGA and BET,and the effects of NVP, BA,ionic strength and reaction time on the morphology and structure of microgels have been investigated.The results indicated that the surface morphology and the porous structures regularly change with the content of cross-linker,the content of NVP,reaction time and ionic strength. Generally,increases of cross-linker,reaction time and ionic strengt made porous size decrease. Additionally,the results indicated that the porous materials without microsphere could obtained when amount of NVP increased up to 50%.Based on these results,a novel approach for controllable preparation of microspheres with porous structure surface morphology could be set up.(2) To enhance the rigidity of the network of polymer in microgel,TiO2 was introduced in the networks to employ following method.The porous P(AM-MAA-NVP) microgels prepared by the freeze-drying were immersed in ethanol containing tetrabutyl titanate(TBT),then the resulting microspheres were placed a moist atmosphere to make TBT in situ hydrolysis and condensation, P(AM-MAA-NVP)/TiO2 composite microsheres were obtained.In the experiment,some factors affected morphology of the microspheres were investigated.The prepared materials were characterized by SEM,FT-IR and TGA.The results indicated that the morphology and the porous structure of the composite microspheres could be altered by changing the cross-linking degree of the porous P(AM-MAA-NVP),ionic strength and the TBOT concentration.Popularly,increases of cross-linking,ionic strength and TBOT concentration could decrease porous size.Based on the results above mentioned,the following results could be obtianed.Enhancement of polymeric chain rigidity or polymeric networks in microhydrogel is an efficient protocol to prepare porous microsphere material,and the porous parameters are easily controlled by altering some conditions.This protocol is commonly suitable to prepare catalyst used in two phase reaction. |
