A new route for synthesis of amphiphilic graft copolymer PE-gPEO containing hydrophobic polyethylene as the backbone and hydrophilic poly(ethylene oxide) a s the side chain has been discussed in this paper.The structu...A new route for synthesis of amphiphilic graft copolymer PE-gPEO containing hydrophobic polyethylene as the backbone and hydrophilic poly(ethylene oxide) a s the side chain has been discussed in this paper.The structure of the copolyme r(such as graft density and graft length),the molecular weights of both polyeth ylene and poly(ethylene oxide) side chain,as well as the molecular weight distr ibution of the copolymer can be designed and controlled easily by this route.Th e molecular weight of poly(ethylene oxide) side chain is proportional to the pol ymerization reaction time and the ethylene oxide monomer concentration,which in dicates the “living" characterization of the anonic polymerization of ethylene oxide.The graft copolymers PE-g-PEO synthesized have been characterized b y 1H-NMR and DSC tests.And the SEM result shows that after adding the amp hiphili c graft copolymer PE-g-PEO as the compatibilizer for the PE/PC polymeric b lend,the compatibility of the blend improved greatly.Therefore,this kind of a mphiphilic graft copolymers can be used as the efficient surfactant for the poly olefin blend and composite materials.展开更多
Poly(N-isopropylacrylamide)(PNIPAAm) grafted onto silica,which may be used for reverse phase chromatography(RPC),was simulated and synthesized for protein separation with temperature-triggered adsorption and desorptio...Poly(N-isopropylacrylamide)(PNIPAAm) grafted onto silica,which may be used for reverse phase chromatography(RPC),was simulated and synthesized for protein separation with temperature-triggered adsorption and desorption.Molecular dynamics simulation at an all-atom level was performed to illustrate the adsorption/desorption behavior of cytochrome c,the model protein,on PNIPAAm-grafted-silica,a temperature responsive adsorbent.At a temperature above the lower critical solution temperature(LCST),the PNIPAAm chains aggregate on the silica surface,forming a hydrophobic surface that is favorable for the hydrophobic adsorption of cytochrome c,which has a high exposure of hydrophobic patches.At temperatures below the LCST,the PNIPAAm chains stretch,forming hydrophilic surface due to hydrogen bonding between PNIPAAm and surrounding water.Desorption of cytochrome c on the PNIPAAm-grafted-silica surface occurs as a result of competition with water,which forms hydrogen bonds with the protein.The conformational transitions of both cytochrome c and PNIPAAm are monitored,providing molecular insight into this temperature-responsive RPC technique.PNIPAAm-grafted-silica beads were synthesized and used for the adsorption and desorption of cytochrome c at approximately 313 K and 290 K,respectively.The experimental results validate the molecular dynamics simulation.In comparison to conventional RPC,using temperature as a driving force for RPC reduces the risk of protein denaturation caused by exposure to chaotropic solvents.Moreover,it simplifies the separation process by avoiding the buffer exchange operations between the steps.展开更多
Metal(Al,Ti,Zr)triflate grafted mesoporous SBA‐15(AlTf/S,TiTf/S,ZrTf/S)samples were synthesizedas inexpensive solid acid materials by a simple one‐pot‐two‐step synthesis methodology.These materials were characteri...Metal(Al,Ti,Zr)triflate grafted mesoporous SBA‐15(AlTf/S,TiTf/S,ZrTf/S)samples were synthesizedas inexpensive solid acid materials by a simple one‐pot‐two‐step synthesis methodology.These materials were characterized by X‐ray diffraction,N2‐sorption,thermogravimetric analysis,Fourier transform infrared spectroscopy(FT‐IR),in‐situ pyridine FT‐IR spectroscopy,and elementalanalysis.ZrTf/S was found to be a highly efficient and reusable solid acid catalyst for ring opening ofepoxides with amines and alcohols and producedβ‐amino alcohols andβ‐alkoxy alcohols respectivelyunder ambient reaction conditions.The ZrTf/S catalyst showed the highest activity,whichwas attributed to its high acidity compared with that of the Ti and Al containing samples.展开更多
文摘A new route for synthesis of amphiphilic graft copolymer PE-gPEO containing hydrophobic polyethylene as the backbone and hydrophilic poly(ethylene oxide) a s the side chain has been discussed in this paper.The structure of the copolyme r(such as graft density and graft length),the molecular weights of both polyeth ylene and poly(ethylene oxide) side chain,as well as the molecular weight distr ibution of the copolymer can be designed and controlled easily by this route.Th e molecular weight of poly(ethylene oxide) side chain is proportional to the pol ymerization reaction time and the ethylene oxide monomer concentration,which in dicates the “living" characterization of the anonic polymerization of ethylene oxide.The graft copolymers PE-g-PEO synthesized have been characterized b y 1H-NMR and DSC tests.And the SEM result shows that after adding the amp hiphili c graft copolymer PE-g-PEO as the compatibilizer for the PE/PC polymeric b lend,the compatibility of the blend improved greatly.Therefore,this kind of a mphiphilic graft copolymers can be used as the efficient surfactant for the poly olefin blend and composite materials.
基金Supported by State Key Laboratory of Chemical Engineering (SKL-ChE-09A05)the National Excellent Doctoral Dissertation Special Fund (200956)
文摘Poly(N-isopropylacrylamide)(PNIPAAm) grafted onto silica,which may be used for reverse phase chromatography(RPC),was simulated and synthesized for protein separation with temperature-triggered adsorption and desorption.Molecular dynamics simulation at an all-atom level was performed to illustrate the adsorption/desorption behavior of cytochrome c,the model protein,on PNIPAAm-grafted-silica,a temperature responsive adsorbent.At a temperature above the lower critical solution temperature(LCST),the PNIPAAm chains aggregate on the silica surface,forming a hydrophobic surface that is favorable for the hydrophobic adsorption of cytochrome c,which has a high exposure of hydrophobic patches.At temperatures below the LCST,the PNIPAAm chains stretch,forming hydrophilic surface due to hydrogen bonding between PNIPAAm and surrounding water.Desorption of cytochrome c on the PNIPAAm-grafted-silica surface occurs as a result of competition with water,which forms hydrogen bonds with the protein.The conformational transitions of both cytochrome c and PNIPAAm are monitored,providing molecular insight into this temperature-responsive RPC technique.PNIPAAm-grafted-silica beads were synthesized and used for the adsorption and desorption of cytochrome c at approximately 313 K and 290 K,respectively.The experimental results validate the molecular dynamics simulation.In comparison to conventional RPC,using temperature as a driving force for RPC reduces the risk of protein denaturation caused by exposure to chaotropic solvents.Moreover,it simplifies the separation process by avoiding the buffer exchange operations between the steps.
基金supported by the CAS President’s International Fellowship Initiative (2016PT028)the National Natural Science Foundation of China (21273225 and 21403219)~~
文摘Metal(Al,Ti,Zr)triflate grafted mesoporous SBA‐15(AlTf/S,TiTf/S,ZrTf/S)samples were synthesizedas inexpensive solid acid materials by a simple one‐pot‐two‐step synthesis methodology.These materials were characterized by X‐ray diffraction,N2‐sorption,thermogravimetric analysis,Fourier transform infrared spectroscopy(FT‐IR),in‐situ pyridine FT‐IR spectroscopy,and elementalanalysis.ZrTf/S was found to be a highly efficient and reusable solid acid catalyst for ring opening ofepoxides with amines and alcohols and producedβ‐amino alcohols andβ‐alkoxy alcohols respectivelyunder ambient reaction conditions.The ZrTf/S catalyst showed the highest activity,whichwas attributed to its high acidity compared with that of the Ti and Al containing samples.
