Monooctadecyl maleate, as a polymerizable surfactant, was synthesized by the mono-esterification of maleic anhydride and octadecanol, and was utilized to surface-modify nano-Fe3O4 particles. A polymerizable magnetic f...Monooctadecyl maleate, as a polymerizable surfactant, was synthesized by the mono-esterification of maleic anhydride and octadecanol, and was utilized to surface-modify nano-Fe3O4 particles. A polymerizable magnetic fluid was obtained by directly dispersing modified nano-Fe3O4 particles into styrene monomer, and the polystyrene/nano-Fe3O4 composite was prepared through free radical polymerization of polymerizable magnetic fluid. The structure and dispersion status in different dispersion phases of modified nano-Fe3O4 particles were studied by Fourier transform infrared （FTIR） spectrometry, X-ray diffraction （XRD） and transmission electron microscopy （TEM）, respectively. The experimental results show that the nano-Fe3O4 particles modified by monooctadecyl maleate with the size of about 7-10 nm can be uniformly dispersed into styrene and fixed in the composite during the procedure of polymerization. Thermogravimetric analysis （TGA） and vibrating sample magnetometry （VSM） indicate that the thermal stability of polystyrene/nano-Fe3O4 composite is improved compared to that of pure polystyrene, and the composite is a sort of superparamagnetic materials.展开更多
Surface molecular motions of amorphous polymeric solids have been directly measured on the basis of scanningviscoelasticity microscopic(SVM)and lateral force microscopic(LFM)measurements.SVM and LFM measurements werec...Surface molecular motions of amorphous polymeric solids have been directly measured on the basis of scanningviscoelasticity microscopic(SVM)and lateral force microscopic(LFM)measurements.SVM and LFM measurements werecarried out for films of conventional monodisperse polystyrene(PS)with sec-butyl and proton-terminated end groups atroom temperature.In the case of the number-average molecular weight,M_(n),less than ca.4.0×10^(4),the surface was in a glass-rubber transition state even though the bulk glass transition temperature,T_(g)was far above room temperature,meaning thatthe surface molecular motion was fairly active compared with that in the bulk.LFM measurements of the,monodisperse PSfilms at various scanning rates and temperatures revealed that the time-temperature superposition was applicable to thesurface mechanical relaxation behavior and also that the surface glass transition temperature,T_(g)^(σ),was depressed incomparison with the bulk one even though the magnitude of M_n was fairly high at 1.40×10~5.The surface molecular motionof monodisperse PS with various chain end groups was investigated on the basis of temperature-dependent scanningviscoelasticity microscopy(TDSVM).The T_(g)^(σ)s for the PS films with M_n of 4.9×10^(6)to 1.45×10^(6)measured by TDSVMwere smaller than those for the bulk one,with corresponding M_ns,and the T_(g)^(σ)s for M_ns smaller than ca.4.0×10^(4)were lowerthan room temperature(293 K).The active thermal molecular motion at the polymeric solid surface can be interpreted interms of an excess free volume near the surface region induced by the surface localization of chain end groups.In the case ofM_n=ca.5.0×10^(4),the T_(g)^(σ)s for theα,ω-diamino-terminated PS(α,ω-PS(NH_2)_2)andα,ω-dicarboxy-terminated PS(α,ω-PS(COOH)_2)films were higher than that of the PS film.The change of T_(g)^(σ)for the PS film with various chain end groups canbe explained in terms of the depth distribution of chain end groups at the surface region depending on the relativehydrophobicity.展开更多
Cross-linkedβ-cyclodextrin polymer/Fe3O4 composite nanoparticles with core-shell structures were prepared via cross linking reaction on the surface of carboxymethylβ-cyclodextrin（CM-β-CD） modified Fe3O4 nanoparti...Cross-linkedβ-cyclodextrin polymer/Fe3O4 composite nanoparticles with core-shell structures were prepared via cross linking reaction on the surface of carboxymethylβ-cyclodextrin（CM-β-CD） modified Fe3O4 nanoparticles inβ-cyclodextrin alkaline solution by using epichlorohydrin as crosslinking agent.The morphology,structure and magnetic properties of the prepared composite nanoparticles were investigated by transmission electron microscopy（TEM）,Fourier transform infrared（FTIR） spectrometry,X-ray diffraction（XRD） measurement,thermogravimetric analysis（TGA） and Vibrating sample magnetometry （VSM）,respectively.展开更多
Super High Definition (SHD) movies were successfully transmitted as streaming contents at about 300 Mbps for the first time over a long distance IP network (more than 3,000 km), in conjunction with the experimental ve...Super High Definition (SHD) movies were successfully transmitted as streaming contents at about 300 Mbps for the first time over a long distance IP network (more than 3,000 km), in conjunction with the experimental verification of traffic control and scalable multicast technologies.展开更多
Cellulose microspheres were fabricated on the basis of sol-gel transition using NaOH/urea/H_(2)O as the solvent system.These microspheres had an average diameter of about 30μm.Upon modification with Fe_(3)O_(4) and p...Cellulose microspheres were fabricated on the basis of sol-gel transition using NaOH/urea/H_(2)O as the solvent system.These microspheres had an average diameter of about 30μm.Upon modification with Fe_(3)O_(4) and poly(DOPAm-co-PFOEA),superhydrophobic magnetic cellulose microspheres were generated,which were analyzed by FTIR,TG,XRD,XPS and water contact angle tests.Magnetic cellulose microspheres contained approximately 15 wt%of Fe_(3)O_(4).Poly(DOPAm-co-PFOEA)/Fe_(3)O_(4)/cellulose microspheres and had a low surface energy and a high water-repellency.These superhydrophobic microspheres were also converted into liquid marbles via an easily scalable process.展开更多
基金Funded by the Natural Science Foundation of Guangdong Province (No. 020891)
文摘Monooctadecyl maleate, as a polymerizable surfactant, was synthesized by the mono-esterification of maleic anhydride and octadecanol, and was utilized to surface-modify nano-Fe3O4 particles. A polymerizable magnetic fluid was obtained by directly dispersing modified nano-Fe3O4 particles into styrene monomer, and the polystyrene/nano-Fe3O4 composite was prepared through free radical polymerization of polymerizable magnetic fluid. The structure and dispersion status in different dispersion phases of modified nano-Fe3O4 particles were studied by Fourier transform infrared （FTIR） spectrometry, X-ray diffraction （XRD） and transmission electron microscopy （TEM）, respectively. The experimental results show that the nano-Fe3O4 particles modified by monooctadecyl maleate with the size of about 7-10 nm can be uniformly dispersed into styrene and fixed in the composite during the procedure of polymerization. Thermogravimetric analysis （TGA） and vibrating sample magnetometry （VSM） indicate that the thermal stability of polystyrene/nano-Fe3O4 composite is improved compared to that of pure polystyrene, and the composite is a sort of superparamagnetic materials.
基金This work was supported in part by a Grant-in-Aid for COE Research"Design and Control of Advanced Molecular Assembly Systems"from the Ministry of Fducation Science Sports and Culture Japan(408CE2005).
文摘Surface molecular motions of amorphous polymeric solids have been directly measured on the basis of scanningviscoelasticity microscopic(SVM)and lateral force microscopic(LFM)measurements.SVM and LFM measurements werecarried out for films of conventional monodisperse polystyrene(PS)with sec-butyl and proton-terminated end groups atroom temperature.In the case of the number-average molecular weight,M_(n),less than ca.4.0×10^(4),the surface was in a glass-rubber transition state even though the bulk glass transition temperature,T_(g)was far above room temperature,meaning thatthe surface molecular motion was fairly active compared with that in the bulk.LFM measurements of the,monodisperse PSfilms at various scanning rates and temperatures revealed that the time-temperature superposition was applicable to thesurface mechanical relaxation behavior and also that the surface glass transition temperature,T_(g)^(σ),was depressed incomparison with the bulk one even though the magnitude of M_n was fairly high at 1.40×10~5.The surface molecular motionof monodisperse PS with various chain end groups was investigated on the basis of temperature-dependent scanningviscoelasticity microscopy(TDSVM).The T_(g)^(σ)s for the PS films with M_n of 4.9×10^(6)to 1.45×10^(6)measured by TDSVMwere smaller than those for the bulk one,with corresponding M_ns,and the T_(g)^(σ)s for M_ns smaller than ca.4.0×10^(4)were lowerthan room temperature(293 K).The active thermal molecular motion at the polymeric solid surface can be interpreted interms of an excess free volume near the surface region induced by the surface localization of chain end groups.In the case ofM_n=ca.5.0×10^(4),the T_(g)^(σ)s for theα,ω-diamino-terminated PS(α,ω-PS(NH_2)_2)andα,ω-dicarboxy-terminated PS(α,ω-PS(COOH)_2)films were higher than that of the PS film.The change of T_(g)^(σ)for the PS film with various chain end groups canbe explained in terms of the depth distribution of chain end groups at the surface region depending on the relativehydrophobicity.
基金financially supported by the Guangdong Natural Science Foundation(No.020891)
文摘Cross-linkedβ-cyclodextrin polymer/Fe3O4 composite nanoparticles with core-shell structures were prepared via cross linking reaction on the surface of carboxymethylβ-cyclodextrin（CM-β-CD） modified Fe3O4 nanoparticles inβ-cyclodextrin alkaline solution by using epichlorohydrin as crosslinking agent.The morphology,structure and magnetic properties of the prepared composite nanoparticles were investigated by transmission electron microscopy（TEM）,Fourier transform infrared（FTIR） spectrometry,X-ray diffraction（XRD） measurement,thermogravimetric analysis（TGA） and Vibrating sample magnetometry （VSM）,respectively.
文摘Super High Definition (SHD) movies were successfully transmitted as streaming contents at about 300 Mbps for the first time over a long distance IP network (more than 3,000 km), in conjunction with the experimental verification of traffic control and scalable multicast technologies.
文摘Cellulose microspheres were fabricated on the basis of sol-gel transition using NaOH/urea/H_(2)O as the solvent system.These microspheres had an average diameter of about 30μm.Upon modification with Fe_(3)O_(4) and poly(DOPAm-co-PFOEA),superhydrophobic magnetic cellulose microspheres were generated,which were analyzed by FTIR,TG,XRD,XPS and water contact angle tests.Magnetic cellulose microspheres contained approximately 15 wt%of Fe_(3)O_(4).Poly(DOPAm-co-PFOEA)/Fe_(3)O_(4)/cellulose microspheres and had a low surface energy and a high water-repellency.These superhydrophobic microspheres were also converted into liquid marbles via an easily scalable process.
