The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN micr...The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN microgels) were synthesized by seed emulsion polymerization. The results obtained by dynamic laser light scattering( DLLS) show that the microgels have good pH /temperature dual sensitivities. The temperature sensitive component and the pH sensitive component inside the microgels have little interference with each other. The rheological properties of the concentrated PNIPAM /PAA IPN microgel dispersions as a function of temperature at pH 4. 0 or 7. 0 were investigated by viscometer,and the results displayed that only at pH 7. 0 the dispersions presented thermoreversible thickening behavior. Then the PNIPAM /PAA fibers were prepared by self-assembly of the PNIPAM /PAA IPN microgels in the ice-crystal templates formed by unidirectional liquid nitrogen freezing method. Field emission scanning electron microscopy( FESEM) images indicate that the PNIPAM /PAA fibers are rounded,randomly orientated and interweaved.展开更多
Positively charged composite nanofiltration （NF） membranes were prepared through interfacial polymerization of poly[2-（N,N-dimethyl amino）ethyl methacrylate]（PDMAEMA） on porous polysulfone （PSF） substrate memb...Positively charged composite nanofiltration （NF） membranes were prepared through interfacial polymerization of poly[2-（N,N-dimethyl amino）ethyl methacrylate]（PDMAEMA） on porous polysulfone （PSF） substrate membranes. The effects of pH on swelling ratio （SR） of the pure crosslinked PDMAEMA membrane and on separation performances of the composite NF membrane were investigated. The results show that the quaternized amino groups produced through interfacial polymerization technique are soluble in both phases, which accelerate the crosslinking reaction as self-catalysts. The swelling/contracting behavior of the pure crosslinked PDMAEMA exhibited a well reversible pH sensitive property. Importantly, the rejection and flux of the composite NF membrane show pH-sensitive behavior in NF process. Furthermore, with the help of a relatively novel method to measure membrane conduction, the true zeta potentials calculated on the basis of the streaming potential measurements proved the pH-sensitive behavior of the NF membrane.展开更多
Three major types of protective coating of wood and wood-based materials have been considered. These three types include the coatings based on carboxyl-containing water-soluble polymers which are easily cross-linked b...Three major types of protective coating of wood and wood-based materials have been considered. These three types include the coatings based on carboxyl-containing water-soluble polymers which are easily cross-linked by inorganic salts or OH-containing compounds, pH-sensitive coatings and polymer multi-layer structures. First of three mentioned approaches allows affecting permeability and enhancing the prevention the loss of water from the surface of wood to its surrounding. The advantage of the second approach is its ability to vary and purposely adjust the polymer composition and the number and distribution of -COOH groups in the chain which make the originally water-soluble polymers completely insoluble. The strong feature of the third approach which includes broad use of hydrogen-bonded films produced by layer-by-layer self-assembly is the possibility of manipulation of coatings stability after construction.展开更多
A novel tripyridylporphyrin monomer,5-[4-[2-（acryloyloxy）ethoxy]phenyl]-10,15,20-tris（4-pyridyl）porphyrin （TrPyP）,was synthesized and polymerized with acrylamide（AM） to prepare the hydrophobically associating ...A novel tripyridylporphyrin monomer,5-[4-[2-（acryloyloxy）ethoxy]phenyl]-10,15,20-tris（4-pyridyl）porphyrin （TrPyP）,was synthesized and polymerized with acrylamide（AM） to prepare the hydrophobically associating water-soluble polymer PAM-TrPyP.The aggregation behavior of porphyrin pendants was investigated by UV-Visible and fluorescence spectra.The polymer displays a strong tendency of hydrophobic association even in dilute solutions.With increasing the concentration,the maximum absorption wavelength of Soret band changes from 416 nm to 407 nm,and the fluorescence corrected for the inner filter effect exhibits moderate concentration quenching.All the results indicate thatπ-πinteraction of porphyrin pendants plays a key role in association of PAM-TrPyP,and H-aggregates of porphyrins are mainly formed in the concentrated solution.On the other hand,dynamic light scattering（DLS） and transmission electron microscopy（TEM） were used to follow the changes in size and structure of the macromolecular assemblies with the concentration increase.The polymer aggregation conformation changes from loose ＂vesicle-like＂ morphology to solid globule accordingly.When pH value of solution decreases to 4.3,pyridine moieties on porphyrin pendants could be protonated and the H-aggregates formed in macromolecular matrix are destroyed by electrostatic repulsion interactions.展开更多
Poly( N isopropylacrylamide methylacrylic acid)[P(NIP co MAA)], a linear water soluble pH precipitating synthetic polymer, was used as a novel separating carrier for the reactants in immunoassay. The P(NIP co MAA) pre...Poly( N isopropylacrylamide methylacrylic acid)[P(NIP co MAA)], a linear water soluble pH precipitating synthetic polymer, was used as a novel separating carrier for the reactants in immunoassay. The P(NIP co MAA) precipitates out of water below a critical pH 5.6 at 37 ℃, and redissolved when the solution pH is above 6.1. This characteristic of the P(NIP co MAA) made it possible to carry out the immunochemical steps of the assay in true solution and then to quickly separate the resulting procucts from the reaction mixtures. The above approach was applied to an assay for the sandwich immunoassay of hepatitis B surface antigen(HBsAg). Sensitivity of this method was close to that of traditional ELISA using same reactants. However, the assay was much faster(assay time decreased from 100—120 min to 45 min). This method has been applied to the determination of the HBsAg levels in human blood serum with satisfactory results. This general technique may also be used for a wide variety of separation processes in addition to immunoassay, in which a specific component is to be isolated for analysis, recovery, or disposal. [WT5HZ]展开更多
基金National Natural Science Foundations of China(Nos.51073033,51373030)the Fundamental Research Funds for the Central Universities,China(No.2232014D3-43)
文摘The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN microgels) were synthesized by seed emulsion polymerization. The results obtained by dynamic laser light scattering( DLLS) show that the microgels have good pH /temperature dual sensitivities. The temperature sensitive component and the pH sensitive component inside the microgels have little interference with each other. The rheological properties of the concentrated PNIPAM /PAA IPN microgel dispersions as a function of temperature at pH 4. 0 or 7. 0 were investigated by viscometer,and the results displayed that only at pH 7. 0 the dispersions presented thermoreversible thickening behavior. Then the PNIPAM /PAA fibers were prepared by self-assembly of the PNIPAM /PAA IPN microgels in the ice-crystal templates formed by unidirectional liquid nitrogen freezing method. Field emission scanning electron microscopy( FESEM) images indicate that the PNIPAM /PAA fibers are rounded,randomly orientated and interweaved.
基金Funded by the National Natural Science Foundation of China (No.50673077)National Basic Research Program of China (No.2006CB708602)
文摘Positively charged composite nanofiltration （NF） membranes were prepared through interfacial polymerization of poly[2-（N,N-dimethyl amino）ethyl methacrylate]（PDMAEMA） on porous polysulfone （PSF） substrate membranes. The effects of pH on swelling ratio （SR） of the pure crosslinked PDMAEMA membrane and on separation performances of the composite NF membrane were investigated. The results show that the quaternized amino groups produced through interfacial polymerization technique are soluble in both phases, which accelerate the crosslinking reaction as self-catalysts. The swelling/contracting behavior of the pure crosslinked PDMAEMA exhibited a well reversible pH sensitive property. Importantly, the rejection and flux of the composite NF membrane show pH-sensitive behavior in NF process. Furthermore, with the help of a relatively novel method to measure membrane conduction, the true zeta potentials calculated on the basis of the streaming potential measurements proved the pH-sensitive behavior of the NF membrane.
文摘Three major types of protective coating of wood and wood-based materials have been considered. These three types include the coatings based on carboxyl-containing water-soluble polymers which are easily cross-linked by inorganic salts or OH-containing compounds, pH-sensitive coatings and polymer multi-layer structures. First of three mentioned approaches allows affecting permeability and enhancing the prevention the loss of water from the surface of wood to its surrounding. The advantage of the second approach is its ability to vary and purposely adjust the polymer composition and the number and distribution of -COOH groups in the chain which make the originally water-soluble polymers completely insoluble. The strong feature of the third approach which includes broad use of hydrogen-bonded films produced by layer-by-layer self-assembly is the possibility of manipulation of coatings stability after construction.
文摘A novel tripyridylporphyrin monomer,5-[4-[2-（acryloyloxy）ethoxy]phenyl]-10,15,20-tris（4-pyridyl）porphyrin （TrPyP）,was synthesized and polymerized with acrylamide（AM） to prepare the hydrophobically associating water-soluble polymer PAM-TrPyP.The aggregation behavior of porphyrin pendants was investigated by UV-Visible and fluorescence spectra.The polymer displays a strong tendency of hydrophobic association even in dilute solutions.With increasing the concentration,the maximum absorption wavelength of Soret band changes from 416 nm to 407 nm,and the fluorescence corrected for the inner filter effect exhibits moderate concentration quenching.All the results indicate thatπ-πinteraction of porphyrin pendants plays a key role in association of PAM-TrPyP,and H-aggregates of porphyrins are mainly formed in the concentrated solution.On the other hand,dynamic light scattering（DLS） and transmission electron microscopy（TEM） were used to follow the changes in size and structure of the macromolecular assemblies with the concentration increase.The polymer aggregation conformation changes from loose ＂vesicle-like＂ morphology to solid globule accordingly.When pH value of solution decreases to 4.3,pyridine moieties on porphyrin pendants could be protonated and the H-aggregates formed in macromolecular matrix are destroyed by electrostatic repulsion interactions.
文摘Poly( N isopropylacrylamide methylacrylic acid)[P(NIP co MAA)], a linear water soluble pH precipitating synthetic polymer, was used as a novel separating carrier for the reactants in immunoassay. The P(NIP co MAA) precipitates out of water below a critical pH 5.6 at 37 ℃, and redissolved when the solution pH is above 6.1. This characteristic of the P(NIP co MAA) made it possible to carry out the immunochemical steps of the assay in true solution and then to quickly separate the resulting procucts from the reaction mixtures. The above approach was applied to an assay for the sandwich immunoassay of hepatitis B surface antigen(HBsAg). Sensitivity of this method was close to that of traditional ELISA using same reactants. However, the assay was much faster(assay time decreased from 100—120 min to 45 min). This method has been applied to the determination of the HBsAg levels in human blood serum with satisfactory results. This general technique may also be used for a wide variety of separation processes in addition to immunoassay, in which a specific component is to be isolated for analysis, recovery, or disposal. [WT5HZ]
