A(R)GET ATRP Polymerization In The Pores Of Modified Mesoporous Materials

Activators generated by electron transfer for atom transfer radical polymerization(AGET ATRP)and activators regenerated by electron transfer for atom transfer radical polymerization(ARGET ATRP)have been widely used due to their insensitivity to air and water,which overcomes the shortcomings of conventional ATRP.However,if AGET ATRP and ARGET ATRP are carried out in the pore channels of mesoporous materials,and different mesoporous materials,initiators,ligands and these two methods are used to polymerize in the pore channels of mesoporous materials,polymers and composites with predetermined structures and properties can be obtained.In this paper,different mesoporous materials,initiators and ligands were selected to conduct in-channel AGET ATRP and ARGET ATRP polymerization.The research contents and main conclusions are as follows:(1)The different mesoporous materials were surface modified by the silane coupling agent KH-550,Polymethyl methacrylate(PMMA)was prepared in the confined nanopores of the mesoporous materials via activators regenerated by ARGET ATRP.The obtained polymers were characterized by infrared(FT-IR),thermogravimetric analysis(TGA),nitrogen adsorption/desorption,differential scanning calorimetry(DSC),scanning electron microscopy(SEM),nuclear magnetic analysis(~1H NMR)and gel permeation chromatography(GPC),respectively.The results demonstrated that KH-550 has been successfully modified for mesoporous materials,and methyl methacrylate(MMA)is polymerized within the modified mesoporous material,and the polymerization products have high thermal stability.The molecular weight of the conventional polymers is higher than that of products obtained in the modified mesoporous channels,but the polymer molecular weight distribution(PDI)in the pore channel is smaller.The internal polymers in the channel have higher syndiotacticity structure,this results in a higher glass transition temperature(T_g),and the Tg value has a positive correlation with the content of the syndiotacticity.(2)The SBA-15 modified by KH-550 was used as"microreactor"and AGET ATRP solution polymerization of MMA was performed inside the pores.Nitrogen adsorption and desorption,GPC,FT-IR,TG,SEM,~1H NMR and other test methods were used to characterize the composites and the PMMA inside and outside the pores.The results indicate that the specific surface area,pore size,pore volume and ordered degree of the composite decreased.Compared with products of external polymerization of pores(O-PMMA),the molecular weight of the polymer PMMA obtained in the pore inside was higher than that of the external polymer PMMA,molecular weight distribution narrowed(1.02-1.29).The initiator bromophenyl ethyl acetate(EBPA)has the highest initiation efficiency.The polymerization products induced by Ethyl 2-bromoisobutyrate(EBiB)have the highest T_g(107℃).The syndiotacticity of the polymer inside the pore channel was lower than that of the polymer outside the pore channel.(3)The mesoporous material SBA-15 modified by KH-550 was used as a"microreactor",and different ligands were utilized to carry out AGET ATRP solution polymerization of methyl methacrylate(MMA).The obtained polymer was characterized by XRD,~1H NMR and GPC.The results showed that MMA successfully polymerized in the channel of SBA-15.Compared with the external product,the internally obtained polymethyl methacrylate(PMMA)exhibited a higher molecular weight,a narrower molecular weight distribution and a higher isotacticity.Additionally,N,N,N’,N,’N’-pentamethyldiethylenetriamine(PMDETA)used as a ligand,lead to the polymerization better controlled(4)The mesoporous materials MCM-41,MCM-48,SBA-15-R,SBA-15-S modified by KH-550 were used as"microreactor"and ARGET ATRP solution polymerization of MMA was performed inside the pores.Compared with AGET ATRP,the amount of products obtained by ARGET ATRP polymerization was smaller,the specific surface area of the composites obtained by AGET ATRP polymerization was smaller than that of ARGET ATRP.The molecular weight of PMMA obtained in the pore inside was higher than that of conventional PMMA,reaching up to 5.1 time,and the molecular weight distribution was narrowed.In the ARGET ATRP method,the content of PMMA-48 was the largest,so the value of T_g was the largest.The Tg of the PMMA made by ARGET ATRP was larger than that by AGET ATRP.