A series of nano silica/silicone modified waterborne polyurethane(WPU) have been synthesized from polytetramethylene glycol and isophorone diisocyanate, dihydroxymethyl propionic acid and triethylamine, ethylenediamin...A series of nano silica/silicone modified waterborne polyurethane(WPU) have been synthesized from polytetramethylene glycol and isophorone diisocyanate, dihydroxymethyl propionic acid and triethylamine, ethylenediamine, trimethylolpropane, nano-SiO2 and the silane coupling agent KH550. The effect of the dosage of nano-SiO2 on the WPU-Si membrane and the coated RDX(cyclotrimethylenetrinitramine) particles have been studied in terms of their surface properties, mechanical properties, and thermal stability. The results showed that with the increase of Si content, the stability of the emulsion reduced gradually. The material with more Si content displayed an increased thermodynamic stability, an increased high temperature resistance, an increased tensile strength and a decreased elongation at break. With the increase of Si content, the surface tension of the material decreased, the bibulous rate reduced, and the contact angle increased gradually, so that the surface tension of the polyurethane and RDX are close to each other which could improve the performance of coating.展开更多
To gain insight into the attachment of =Si^＋ （SC） ion （regarded as guest） to the lowest generation, NH2-terminated poly（amidoamine） （PAMAM） dendrimers （regarded as host） in the liquid phase, density functio...To gain insight into the attachment of =Si^＋ （SC） ion （regarded as guest） to the lowest generation, NH2-terminated poly（amidoamine） （PAMAM） dendrimers （regarded as host） in the liquid phase, density functional theory is used to investigate the structures and energetics of the host-guest complex. The effect of solvent on the structures and energetics is also investigated. Various initial configurations of the ion bound to PAMAM are tested, and two stable conformers are found, i.e, types A （=Si^＋ is bound to the amine site） and C （=Si^＋ is bound to the amide site）. Types A and C are the most stable due to the chemical bond formations of Si-N° （amine nitrogen atoms） and Si-O, respectively. The IR spectra for the lowest energy conformers are thoroughly analyzed and compared with the available experimental data.展开更多
A new method to chemically modify the surface of nanosized-SiO2 was studied in this paper.Nanosized-SiO2 was grafted with hyperbranched poly(amin ester)through one-spot polycondensation between AB2 monomer and active ...A new method to chemically modify the surface of nanosized-SiO2 was studied in this paper.Nanosized-SiO2 was grafted with hyperbranched poly(amin ester)through one-spot polycondensation between AB2 monomer and active hydroxyl on silica surface in present of catalyst.Compared with the results of FTIR and TEM,it is found hyperbranched poly(amin ester)is successfully grafted on the surface of nanosized-SiO2 and the surface properties have been changed with an expected way.The results indicate that nanosized-SiO2 grafted with hyperbranched poly(amin ester)has better dispersion in the ethanol or chloroform than that unmodified.展开更多
A kind of modified epoxy resins was obtained by condensation of epoxy resin with silicic acid tetraethyl ester（TEOS） and nano-SiO2. The reactions were performed with hydrochloric acid as a catalyst at 63 ℃. The str...A kind of modified epoxy resins was obtained by condensation of epoxy resin with silicic acid tetraethyl ester（TEOS） and nano-SiO2. The reactions were performed with hydrochloric acid as a catalyst at 63 ℃. The structure, thermal stability and morphological characteristics of the modified epoxy resins were studied through infrared spectra（FT-IR） analysis, thermogravimetric（TG） analysis and scanning electron microscopy respectively. It has been found from the IR and TG study that modified epoxy resins have greater thermal stability than epoxy resins, and its thermal stability has been improved by the formation of inter-crosslinked network structure. The modified epoxy resins exhibit heterogeneous morphology and heterogeneity increases with more TEOS feeding, which in turn confirms the formation of inter-crosslinked network structure in modified epoxy resins.展开更多
Cement improves properties of soil materials, such as durability, stiffness, strength and moisture susceptibility. Each of them needs different cement contents that might not be suitable for other properties. Typicall...Cement improves properties of soil materials, such as durability, stiffness, strength and moisture susceptibility. Each of them needs different cement contents that might not be suitable for other properties. Typically, high cement content is desirable for durability, but not for shrinkage and cracking issues on the surface. Thus, improving durability with low cement content while complying with other requirements is an ideal aim, which may be achieved by pozzolanic supplementary products. Pozzolans contribute in hydration reactions and optimise cement consumptions in favour of durable and low shrinkage products. In this paper, the mixes of nano-silica and fly ash are considered to investigate their effect on strength, durability and shrinkage of modified CRB （crushed rock base） material. In the end, the benefits and features of nano-silica as a pozzolanic material will be focused and discussed more for effective cement consumption in soils.展开更多
2,3-Bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl) fumaronitrile (TPE-TPA-FN or TTF), which possesses aggregation-induced emission (AIE) characteristic, is doped in organically modified silica (ORMOSIL) na...2,3-Bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl) fumaronitrile (TPE-TPA-FN or TTF), which possesses aggregation-induced emission (AIE) characteristic, is doped in organically modified silica (ORMOSIL) nanoparticles. By increasing the weight ratio of TTF to the precursor of silica nanoparticles (the quantities of the precursors were kept the same), the fluorescence intensity of nanoparticles increased correspondingly, due to the formation of larger AIE dots in the cores of ORMOSIL nanoparticles. The fluorescent and biocompatible nanoprobes were then utilized for in vitro imaging of HeLa cells. Two-photon fluorescence microscopy clearly illustrated that the nanoparticles have the capacity of nucleus permeability, as well as cytoplasm staining towards tumor cells. Our experimental results may offer a promising method for fast and bright fluorescence imaging, as well as bio-molecule/drug delivery to cell nucleus.展开更多
基金the financial support by the National Natural Science Foundation of China(No.20973022 and No.11472048)
文摘A series of nano silica/silicone modified waterborne polyurethane(WPU) have been synthesized from polytetramethylene glycol and isophorone diisocyanate, dihydroxymethyl propionic acid and triethylamine, ethylenediamine, trimethylolpropane, nano-SiO2 and the silane coupling agent KH550. The effect of the dosage of nano-SiO2 on the WPU-Si membrane and the coated RDX(cyclotrimethylenetrinitramine) particles have been studied in terms of their surface properties, mechanical properties, and thermal stability. The results showed that with the increase of Si content, the stability of the emulsion reduced gradually. The material with more Si content displayed an increased thermodynamic stability, an increased high temperature resistance, an increased tensile strength and a decreased elongation at break. With the increase of Si content, the surface tension of the material decreased, the bibulous rate reduced, and the contact angle increased gradually, so that the surface tension of the polyurethane and RDX are close to each other which could improve the performance of coating.
文摘To gain insight into the attachment of =Si^＋ （SC） ion （regarded as guest） to the lowest generation, NH2-terminated poly（amidoamine） （PAMAM） dendrimers （regarded as host） in the liquid phase, density functional theory is used to investigate the structures and energetics of the host-guest complex. The effect of solvent on the structures and energetics is also investigated. Various initial configurations of the ion bound to PAMAM are tested, and two stable conformers are found, i.e, types A （=Si^＋ is bound to the amine site） and C （=Si^＋ is bound to the amide site）. Types A and C are the most stable due to the chemical bond formations of Si-N° （amine nitrogen atoms） and Si-O, respectively. The IR spectra for the lowest energy conformers are thoroughly analyzed and compared with the available experimental data.
文摘A new method to chemically modify the surface of nanosized-SiO2 was studied in this paper.Nanosized-SiO2 was grafted with hyperbranched poly(amin ester)through one-spot polycondensation between AB2 monomer and active hydroxyl on silica surface in present of catalyst.Compared with the results of FTIR and TEM,it is found hyperbranched poly(amin ester)is successfully grafted on the surface of nanosized-SiO2 and the surface properties have been changed with an expected way.The results indicate that nanosized-SiO2 grafted with hyperbranched poly(amin ester)has better dispersion in the ethanol or chloroform than that unmodified.
文摘A kind of modified epoxy resins was obtained by condensation of epoxy resin with silicic acid tetraethyl ester（TEOS） and nano-SiO2. The reactions were performed with hydrochloric acid as a catalyst at 63 ℃. The structure, thermal stability and morphological characteristics of the modified epoxy resins were studied through infrared spectra（FT-IR） analysis, thermogravimetric（TG） analysis and scanning electron microscopy respectively. It has been found from the IR and TG study that modified epoxy resins have greater thermal stability than epoxy resins, and its thermal stability has been improved by the formation of inter-crosslinked network structure. The modified epoxy resins exhibit heterogeneous morphology and heterogeneity increases with more TEOS feeding, which in turn confirms the formation of inter-crosslinked network structure in modified epoxy resins.
文摘Cement improves properties of soil materials, such as durability, stiffness, strength and moisture susceptibility. Each of them needs different cement contents that might not be suitable for other properties. Typically, high cement content is desirable for durability, but not for shrinkage and cracking issues on the surface. Thus, improving durability with low cement content while complying with other requirements is an ideal aim, which may be achieved by pozzolanic supplementary products. Pozzolans contribute in hydration reactions and optimise cement consumptions in favour of durable and low shrinkage products. In this paper, the mixes of nano-silica and fly ash are considered to investigate their effect on strength, durability and shrinkage of modified CRB （crushed rock base） material. In the end, the benefits and features of nano-silica as a pozzolanic material will be focused and discussed more for effective cement consumption in soils.
基金the National Basic Research Program of China (973 Program, 2013CB834704 and 2011CB503700)the National Natural Science Foundation of China (61275190)
文摘2,3-Bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl) fumaronitrile (TPE-TPA-FN or TTF), which possesses aggregation-induced emission (AIE) characteristic, is doped in organically modified silica (ORMOSIL) nanoparticles. By increasing the weight ratio of TTF to the precursor of silica nanoparticles (the quantities of the precursors were kept the same), the fluorescence intensity of nanoparticles increased correspondingly, due to the formation of larger AIE dots in the cores of ORMOSIL nanoparticles. The fluorescent and biocompatible nanoprobes were then utilized for in vitro imaging of HeLa cells. Two-photon fluorescence microscopy clearly illustrated that the nanoparticles have the capacity of nucleus permeability, as well as cytoplasm staining towards tumor cells. Our experimental results may offer a promising method for fast and bright fluorescence imaging, as well as bio-molecule/drug delivery to cell nucleus.
