Reverse Atom Transfer Radical Polymerization In Mesoporous Materials SBA-15

In the recent ten years,reverse atom transfer radical polymerization（RATRP）is a research topic in the polymer field owing to its unique advantages.Many significant progresses have been made in the polymerization mechanism and preparation of special polymer.However,the influence of confined-space on the RATRP polymerization in the nano-space of mesoporous materials was rarely reported.In this thesis,mesoporous silica SBA-15 with different pore size channels were synthesized in diverse conditions.And then,the products（some of them were grafted with initiator）were used as the“micro-reactor”in the RATRP polymerization.The main research contents and results are as follows:（1）SBA-15 was synthesized using polyethylene oxide–polypropylene oxide–polyethylene oxide（PEO-PPO-PEO）as template,tetraethoxysilane（TEOS）or sodium metasilicate（Na₂SiO₃）as silica source,trimethylbenzene（TMB）or1,3,5-tris（1-methylethyl）-benzene（TIPB）as pore-expanding agent.The products were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,N₂adsorption-desorption,and transmission electron microscope（TEM）.The results suggest that mesoporous material SBA-15 was synthesized successfully with the pore size vary from 8 to 30 nm.The structures of SBA-15 were irregular when the pore-expanding agent was added.And with uncontinuous dropping of silica source,the pore size of the silica was hierarchical.The appropriate increase of the dropping speed was a way to make the pore size distribution uniform,although the specific surface area,pore volume increased while the pore size decreased.The adjusting temperatures of pre-synthesis and hydrothermal reaction were benefit to the increasement of mesoporous pore size but harmful to pore channel,and led to the pore size distribution wider.（2）Methyl methacrylate（MMA）was polymerized in different pore size of SBA-15 by RATRP,then the obtained products were characterized by Nitrogen adsorption test,XRD,SEM,TEM,Fourier transform infrared spectroscopy（FT-IR）,thermogravimetry analysis（TGA）,differential scanning calorimetry（DSC）,hydrogen nuclear magnetic resonance（¹H-NMR）and gel permeation chromatography（GPC）.The results suggest that the molecular weights of inner polymer were significant higher than outer polymer.The number average molecular weight（M_n）and weight average molecular weight（M_w）of the inside polymer in SBA-15 with pore size of 22nm were 1.86 times and 1.71 times than that with pore size of 8 nm,respectively.With the channel size increasing,the glass transition temperature（T_g）and syndiotactic ratios of the PMMA polymerized inside were all improved.（3）The initiator was grafted onto the SBA-15,and then initiated the solution RATRP polymerization inside it.The obtained products were characterized by FT-IR,Nitrogen adsorption test,TGA,XRD,SEM,TEM,GPC,DSC,and ¹H-NMR.The results indicate that the polymer amounts in the composite（PMS-SI）initiated by grafted initiator were higher than PMS initiated by adsorption method.In addition,the T_g,molecular weight,isotacticity of the PMMA were all higher,and the molecular weight distributions were narrower than that obtained in adsorption method.