Well - defined diblock copolymers Of styrene (St ) and ethylene oxide (EO )have been prepared by sequential living anionic polymerization of the twocomonomers in THF. Diphenyl methyl potassium has been used as initiat...Well - defined diblock copolymers Of styrene (St ) and ethylene oxide (EO )have been prepared by sequential living anionic polymerization of the twocomonomers in THF. Diphenyl methyl potassium has been used as initiator. Theblock copolymers were characterized in detail by methods Of size exclusion chromatography (SEC ) , 1H - Nab, FT - IR, dynamic mechanical analysis(Daal ) and WAXD.展开更多
The present paper covers the poly (ethylene oxide) macromer with vinyl benzyl terminal group (PEO-VB) prepared by deactivation of the alkoxide function of mono-functional "living" PEO chains with vinyl benzy...The present paper covers the poly (ethylene oxide) macromer with vinyl benzyl terminal group (PEO-VB) prepared by deactivation of the alkoxide function of mono-functional "living" PEO chains with vinyl benzyl chloride (VBC). The obtained macromers were subjected to careful purification and detailed characterization. A new kind of amphiphilic polystyrene-g-poly(ethylene oxide) (PS-g-PEO) with both mi-crophase separated and PEO side chains was synthesized from radical copolymerization of PEO-VB macromer with styrene monomer. An improved purification method, referred as "selective dissolvation", was established for the isolation of graft copolymers from the grafting products, and the purity and yield of the purified copolymers were satisfactory. The well-defined structure of the purified copolymers was confirmed by IR, 1H NMR and GPC. The bulk composition of the graft copolymers was determined by a well-established first derivative UV spectrometry. Various experimental parameters controlling the展开更多
Well-defined nonionic hydrophilic ω-acryloyl poly(ethylene oxide) macro-monomer (PEO-A) has been prepared by living anionic polymerization of ethylene oxidewith diphenyl methyl potassium as the initiator and acryloyl...Well-defined nonionic hydrophilic ω-acryloyl poly(ethylene oxide) macro-monomer (PEO-A) has been prepared by living anionic polymerization of ethylene oxidewith diphenyl methyl potassium as the initiator and acryloyl chloride as the reaction termi-nating agent. The polymer was characterized by FTIR and SEC. The emulsifier-free emul-sion polymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA) containingvarious concentrations of PEO-A was studied. In all cases stable emulsion coplymerizationsof MMA and BA were obtained. The stabilizing effect was found to be dependent on themolecular weight and the feed amount of the macromonomer.展开更多
This paper reported the research results concerning the surface characterization ofpolystyrene-graft-w-stearyl poly(ethylene oxide) (PS-g-SPEO) by means of XPS,contactangle measurement and TEM, and its in vitro blood ...This paper reported the research results concerning the surface characterization ofpolystyrene-graft-w-stearyl poly(ethylene oxide) (PS-g-SPEO) by means of XPS,contactangle measurement and TEM, and its in vitro blood compatibility assessment by measuringthe plasma recalcification time (RT) and partial thromboplastin time (PTT). The XPSresults demonstrated that the surface and bulk composition of the PS-g-SPEO graftcopolymers differ remarkably from each other,and that SPEO component was constantlyenriched at the copolymer/air interface. Contact angle studies indicated that the surfacewater wettability can be adjusted effectively by changing the composition of the copolymer.PS-g-SPEO graft copolymers can undergo microphase separation as clearly illustrated byTEM photographs. The relationship between the surface properties of PS-g-SPEO graftcopolymer and its blood compatibility was also discussed.展开更多
Methoxy poly(ethylene oxide)-b-poly(ethyl cyanoacrylate) (mPEG-b-PECA), amphiphilic block copolymer, was synthesized via oxyanion-initiated polymerization with a sodium alcoholate-terminated monomethoxy poly(ethylene ...Methoxy poly(ethylene oxide)-b-poly(ethyl cyanoacrylate) (mPEG-b-PECA), amphiphilic block copolymer, was synthesized via oxyanion-initiated polymerization with a sodium alcoholate-terminated monomethoxy poly(ethylene glycol) as the macroinitiator. mPEG-b-PECA was characterized by GPC, 1H-NMR and FTIR. The results indicate that the structure of mPEG-b-PECA is well controlled with narrow molecular weight distribution. The dexamethasone (DXM)-loaded mPEG-b-PECA nanoparticles (NPs) were prepared by the nanoprecipitation technique and characterized by LPSA, 1H-NMR and TEM. The DXM-loaded mPEG-b-PECA NPs are of spherical shape with the size of less than 100 nm. The drug-loaded amount (DL) and encapsulation efficiency (EE) of DXM-loaded NPs were investigated by HPLC. The results show that DXM can be effectively incorporated into mPEG-b-PECA NPs, which provides a potential delivery system for DXM and other hydrophobic drugs.展开更多
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
The biodegradation behavior in vitro and in vivo of polycaprolactone poly (ethylene oxide) block copolymers ( P C E) has been reported in detail. Photodegradation testof P C E was performed by exposure to U Vlight. Th...The biodegradation behavior in vitro and in vivo of polycaprolactone poly (ethylene oxide) block copolymers ( P C E) has been reported in detail. Photodegradation testof P C E was performed by exposure to U Vlight. The mechanical properties and the inherentviscosity of P C Esamples which are subjected to photodegradation were determined . Thephotodegradation rate of P C E was much more faster than its hydrolysis rate and wasincreased with increasing poly(ethylene oxide) content. The experimental results alsoindicated that the pure poly(ethylene oxide) ( P E O) can not be photodegraded alone. Amechanism forthe photodegradation of P C Ecopolymers was proposed :thecarbonylgroupsin P C Lsegmentscatalyze the breakage ofthe P E Ochains by a seriesof U Vinitiated freeradicalreactions. When the free radicals induce the degradation of P E O segments in P C E,thephotodegradation of P C E mainly occursin P E Osegments.展开更多
The solution property of amphiphilic graft copolymer has been examined by means of NMR,TEM and viscometry. It is found that water and toluene are selective solvent for PSt- g- PEO. When it is dissolved in water, micel...The solution property of amphiphilic graft copolymer has been examined by means of NMR,TEM and viscometry. It is found that water and toluene are selective solvent for PSt- g- PEO. When it is dissolved in water, micelle can be formed with hydrophobic PSt backbone as the core and hydrophilic PEO side chains as the shell. On the other hand, in selective solvent toluene, the reversed- micelle can be formed with PEO as core and PSt as the shell. In toluene, with an increase in concentration, the conformation of PSt- g- PEO can be transformed from stretched single molecule to spherical reversed- micelle. The critical micelle concentration(CMC) is determined at different temperature and with the increase of temperature and the content of PEO the reversed- micelle can be formed in lower concentrations.展开更多
文摘Well - defined diblock copolymers Of styrene (St ) and ethylene oxide (EO )have been prepared by sequential living anionic polymerization of the twocomonomers in THF. Diphenyl methyl potassium has been used as initiator. Theblock copolymers were characterized in detail by methods Of size exclusion chromatography (SEC ) , 1H - Nab, FT - IR, dynamic mechanical analysis(Daal ) and WAXD.
基金Supported by the National Natural Science Foundation of China The State Education Commission of China
文摘The present paper covers the poly (ethylene oxide) macromer with vinyl benzyl terminal group (PEO-VB) prepared by deactivation of the alkoxide function of mono-functional "living" PEO chains with vinyl benzyl chloride (VBC). The obtained macromers were subjected to careful purification and detailed characterization. A new kind of amphiphilic polystyrene-g-poly(ethylene oxide) (PS-g-PEO) with both mi-crophase separated and PEO side chains was synthesized from radical copolymerization of PEO-VB macromer with styrene monomer. An improved purification method, referred as "selective dissolvation", was established for the isolation of graft copolymers from the grafting products, and the purity and yield of the purified copolymers were satisfactory. The well-defined structure of the purified copolymers was confirmed by IR, 1H NMR and GPC. The bulk composition of the graft copolymers was determined by a well-established first derivative UV spectrometry. Various experimental parameters controlling the
文摘Well-defined nonionic hydrophilic ω-acryloyl poly(ethylene oxide) macro-monomer (PEO-A) has been prepared by living anionic polymerization of ethylene oxidewith diphenyl methyl potassium as the initiator and acryloyl chloride as the reaction termi-nating agent. The polymer was characterized by FTIR and SEC. The emulsifier-free emul-sion polymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA) containingvarious concentrations of PEO-A was studied. In all cases stable emulsion coplymerizationsof MMA and BA were obtained. The stabilizing effect was found to be dependent on themolecular weight and the feed amount of the macromonomer.
基金This work was supported by the National Natural Science Foundation of China and the State Education Committee of China.
文摘This paper reported the research results concerning the surface characterization ofpolystyrene-graft-w-stearyl poly(ethylene oxide) (PS-g-SPEO) by means of XPS,contactangle measurement and TEM, and its in vitro blood compatibility assessment by measuringthe plasma recalcification time (RT) and partial thromboplastin time (PTT). The XPSresults demonstrated that the surface and bulk composition of the PS-g-SPEO graftcopolymers differ remarkably from each other,and that SPEO component was constantlyenriched at the copolymer/air interface. Contact angle studies indicated that the surfacewater wettability can be adjusted effectively by changing the composition of the copolymer.PS-g-SPEO graft copolymers can undergo microphase separation as clearly illustrated byTEM photographs. The relationship between the surface properties of PS-g-SPEO graftcopolymer and its blood compatibility was also discussed.
基金Supported by the Key Project of Tianjin Municipal Natural Science Foundation (Grant No. 08JCZDJC17200)Tianjin Municipal Natural Science Foundation (Grant No. 08JCYBJC01800)National Natural Science Foundation of China (Grant No. 30672554)
文摘Methoxy poly(ethylene oxide)-b-poly(ethyl cyanoacrylate) (mPEG-b-PECA), amphiphilic block copolymer, was synthesized via oxyanion-initiated polymerization with a sodium alcoholate-terminated monomethoxy poly(ethylene glycol) as the macroinitiator. mPEG-b-PECA was characterized by GPC, 1H-NMR and FTIR. The results indicate that the structure of mPEG-b-PECA is well controlled with narrow molecular weight distribution. The dexamethasone (DXM)-loaded mPEG-b-PECA nanoparticles (NPs) were prepared by the nanoprecipitation technique and characterized by LPSA, 1H-NMR and TEM. The DXM-loaded mPEG-b-PECA NPs are of spherical shape with the size of less than 100 nm. The drug-loaded amount (DL) and encapsulation efficiency (EE) of DXM-loaded NPs were investigated by HPLC. The results show that DXM can be effectively incorporated into mPEG-b-PECA NPs, which provides a potential delivery system for DXM and other hydrophobic drugs.
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.
文摘The biodegradation behavior in vitro and in vivo of polycaprolactone poly (ethylene oxide) block copolymers ( P C E) has been reported in detail. Photodegradation testof P C E was performed by exposure to U Vlight. The mechanical properties and the inherentviscosity of P C Esamples which are subjected to photodegradation were determined . Thephotodegradation rate of P C E was much more faster than its hydrolysis rate and wasincreased with increasing poly(ethylene oxide) content. The experimental results alsoindicated that the pure poly(ethylene oxide) ( P E O) can not be photodegraded alone. Amechanism forthe photodegradation of P C Ecopolymers was proposed :thecarbonylgroupsin P C Lsegmentscatalyze the breakage ofthe P E Ochains by a seriesof U Vinitiated freeradicalreactions. When the free radicals induce the degradation of P E O segments in P C E,thephotodegradation of P C E mainly occursin P E Osegments.
文摘The solution property of amphiphilic graft copolymer has been examined by means of NMR,TEM and viscometry. It is found that water and toluene are selective solvent for PSt- g- PEO. When it is dissolved in water, micelle can be formed with hydrophobic PSt backbone as the core and hydrophilic PEO side chains as the shell. On the other hand, in selective solvent toluene, the reversed- micelle can be formed with PEO as core and PSt as the shell. In toluene, with an increase in concentration, the conformation of PSt- g- PEO can be transformed from stretched single molecule to spherical reversed- micelle. The critical micelle concentration(CMC) is determined at different temperature and with the increase of temperature and the content of PEO the reversed- micelle can be formed in lower concentrations.
