A series of thermoreversible konjac glucomannan gels crosslinked by organic borate were prepared. Required amount of hydrophilic SiO2 was added into the konjac glucomannan solutions before the crosslinking reaction, T...A series of thermoreversible konjac glucomannan gels crosslinked by organic borate were prepared. Required amount of hydrophilic SiO2 was added into the konjac glucomannan solutions before the crosslinking reaction, The gel network was formed through the crosslinking reaction between borate ions dissociated from organic borate and the cis-diol hydroxyl groups on the mannose units of polysaccharide chains. The rheological properties of the complex gels were studied by dynamic viscoelastic measurement. The gelation kinetics of the complex gels was studied and the critical getation points of the gels were exactly determined by the Winter-Chambon criterion. The effects of temperature and composite ratio on the shear storage modulus （G＇）, the loss modulus （G＂） and the sol-gel transition points were investigated.展开更多
Three different precursors of boron-aqua and glycerol solutions of boric acid and ethanol solution of trimethyl borate were used for the preparation of organic–inorganic advanced materials. The films and bulk materia...Three different precursors of boron-aqua and glycerol solutions of boric acid and ethanol solution of trimethyl borate were used for the preparation of organic–inorganic advanced materials. The films and bulk materials samples were heat treated at 100, 400, 800？C for 2 h. The hybrid samples were stable and transparent until 100？C. The further increase of temperature to 400？C led to destruction of samples, and at 800？C they were molten. The structural changes during the pyrolysis were studied by Fourier transform infrared spectroscopy, differential thermal analysis, and X-ray diffraction. Details of surface morphology were observed by scanning electron microscopy. The obtained BO_3 and BO_4 groups were identified in the molten materials after pyrolysis. The quantities and order of borate structural units as well as residual carbon in the networks depended on boron precursor type. PVA/PEG/B_2O_3 hybrid materials were proved to be appropriate precursors for synthesizing borate and carboborate glass and carbon/borate glass nanocomposites. To access the impact of the experimental conditions on the structural changes of the nanocomposites, cluster analysis of the IR-spectral data was used as a classification method.展开更多
基金Funded by Chinese Natural Science Foundation Committee(No.50673080)
文摘A series of thermoreversible konjac glucomannan gels crosslinked by organic borate were prepared. Required amount of hydrophilic SiO2 was added into the konjac glucomannan solutions before the crosslinking reaction, The gel network was formed through the crosslinking reaction between borate ions dissociated from organic borate and the cis-diol hydroxyl groups on the mannose units of polysaccharide chains. The rheological properties of the complex gels were studied by dynamic viscoelastic measurement. The gelation kinetics of the complex gels was studied and the critical getation points of the gels were exactly determined by the Winter-Chambon criterion. The effects of temperature and composite ratio on the shear storage modulus （G＇）, the loss modulus （G＂） and the sol-gel transition points were investigated.
基金supported by the Spanish Ministry of Education and Science (Project CTM2012-39183)the Generalitat de Catalunya (Grup Consolidat 2014SGR1017)support of H2020 program of the European Union (project Materials Networking)
文摘Three different precursors of boron-aqua and glycerol solutions of boric acid and ethanol solution of trimethyl borate were used for the preparation of organic–inorganic advanced materials. The films and bulk materials samples were heat treated at 100, 400, 800？C for 2 h. The hybrid samples were stable and transparent until 100？C. The further increase of temperature to 400？C led to destruction of samples, and at 800？C they were molten. The structural changes during the pyrolysis were studied by Fourier transform infrared spectroscopy, differential thermal analysis, and X-ray diffraction. Details of surface morphology were observed by scanning electron microscopy. The obtained BO_3 and BO_4 groups were identified in the molten materials after pyrolysis. The quantities and order of borate structural units as well as residual carbon in the networks depended on boron precursor type. PVA/PEG/B_2O_3 hybrid materials were proved to be appropriate precursors for synthesizing borate and carboborate glass and carbon/borate glass nanocomposites. To access the impact of the experimental conditions on the structural changes of the nanocomposites, cluster analysis of the IR-spectral data was used as a classification method.
