A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobi...A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobic aggregation of the polymeric chains in THF-H2O dispersion media, which was induced by a steady increase in the water content. Results showed that the addition of a small amount of surfactant （SDBS） could significantly narrow the size distribution of the colloidal spheres. The size distribution of the colloidal spheres was determined by the concentrations of azo polymer and the amount of surfactant in the systems. When the concentrations of polymer and surfactant amount were in a proper range, colloidal spheres with narrow size distribution could be obtained. The colloidal spheres formed by this method could be elongated along the polarization direction of the laser beams to be a new type of the colloid-based functional materials. upon Ar^＋ laser irradiation. The colloidal spheres are considered展开更多
Three series of amorphous copolymers containing azobenzene groups with various substituents and certain amounts of crosslinkable acrylic groups were prepared. The cross-linked polymer films were obtained by thermal po...Three series of amorphous copolymers containing azobenzene groups with various substituents and certain amounts of crosslinkable acrylic groups were prepared. The cross-linked polymer films were obtained by thermal polymerization of the acrylic groups in the copolymers, during which, by controlling the time of cross-linking reaction, the films can be made with different cross-linking degree （from 0 to 32%, which was monitored by FT-IR spectra measurement）. Photo-induced alignment process of the films was performed under irradiation with linearly polarized light at 442 nm, and the effect of cross-linking degree on the photo-induced alignment rate was investigated. The dynamics of the photo-induced alignment was analyzed with biexponential curve fitting. The photo-induced alignment rate and the maximum transmittance of the films decreased because of the cross-linking. Furthermore, for the cross-linked samples, it was found that their saturated value of transmittances keep constant after repeated ＂writing＂ and ＂erasing＂ cycles. The findings reveal that the cross-linking of the film can effectively restrain the phototactic mass transport of azopolymer during irradiation by polarized light. The relationship between the cross-linking degree and the photo-induced alignment behavior of azopolymer is discussed in detail.展开更多
In this work, surface-relief-grating formation behavior was studied by using two hyperbranched azo polymers. The hyperbranched polymers containing pseudo-stilbene type azo chromophores throughout the hyperbranched str...In this work, surface-relief-grating formation behavior was studied by using two hyperbranched azo polymers. The hyperbranched polymers containing pseudo-stilbene type azo chromophores throughout the hyperbranched structure were synthesized by step-growth polycondensation of AB2 type monomers. The AB2 monomer, 4-（4＇-（bis（2-chloroethyl）amino）- phenylazo）benzoic acid （BAA）, was prepared through azo-coupling reaction between N,N＇-bis（2-chloroethyl）aniline and 4- aminobenzenic acid. The another AB2 monomer, 4-（4＇-（bis（2-chloroethyl）amino）phenylazo）-3-nitro-benzoic acid （BANA）, was prepared through azo-coupling reaction between N,N-bis（2-chloroethyl）aniline and 3-nitro-4-aminobenzenic acid. The hyperbranched polymers （PBAA and PBANA） were prepared through nucleophilic substitution reaction of BAA and BANA, respectively. The polymers synthesized were characterized by using spectroscopic methods and thermal analysis. The photoinduced dichroism and photo-induced surface-relief-grating （SRG） formation of the hyperbranched polymers were investigated upon irradiation with Ar＋ laser at 488 nm. PBAA shows typical photoinduced dichroism SRG formation behavior. On the contrary, PBANA does not show the photoresponsive properties. The results indicate that the nitro at the ortho position of azo group of PBANA shows the effect of inhibiting the photoinduced variations. The effect can be attributed to the blockage of the trans-cis isomerization of the azobenzene moieties by the steric hindrance.展开更多
Three epoxy-based azo polymers （PEP-AZ-C1, PEP-AZ-CN and PEP-AZ-NT） with high chromophore density were synthesized by using post-polymerization azo-coupling reactions between epoxy-based precursor polymer （PEP-AN）...Three epoxy-based azo polymers （PEP-AZ-C1, PEP-AZ-CN and PEP-AZ-NT） with high chromophore density were synthesized by using post-polymerization azo-coupling reactions between epoxy-based precursor polymer （PEP-AN） and diazonium salts of 4-chloroaniline, 4-aminobenzonitrile and 4-nitroaniline, respectively. The structures and properties of the azo polymers were characterized by using 1H-NMR, FT-IR, UV-Vis and thermal analyses. The photoinduced birefringence of the azo polymers was studied by irradiating spin-coated films of the polymers with laser beam at three different wavelengths （488, 532, and 589 nm）. The results indicate that the photoinduced birefringence of the azo polymers is related with the electron-withdrawing group on azo chromophores and the excitation wavelength. The excitation wavelength that can cause the efficient responses is determined by the absorption band positions of the a~：o chromophores, which are mainly affected by the electron-withdrawing group on the chromophores. Therefore, the,. azo polymers containing chromophores with different electron-withdrawing groups show different respon,;ive behavior to the irradiation light at different wavelengths. When irradiated with 488 nm light, PEP-AZ-Cl shows the shortest time to reach the saturated birefringence but with the lowest saturation birefringence level compared with the other two azo polymers. When irradiated with 532 nm light, PEP-AZ-CN shows the shortest time to reach the saturated birefringence. When irradiated with 532 and 589 nm light, PEP-AZ-NT shows the highest saturation birefringence level.展开更多
A reversed duckweed polymeric LB film was fabricated by a new kind of amphiphilic polymer which was composed of hexanedlamine-epichlorohydrin slightly crosslinked hydrophilic network and hydrophobic chains conatining ...A reversed duckweed polymeric LB film was fabricated by a new kind of amphiphilic polymer which was composed of hexanedlamine-epichlorohydrin slightly crosslinked hydrophilic network and hydrophobic chains conatining p-nitroazobenzene group. This amphiphilic polymer can form stable liquid-condensed monolayer and be transferred as Z-type polymeric LB films. This LB film combines the order and mobility and it has a well-estab- lished layer structure and azo chromphore is in an isotropic state in each layer. Optical birefringence and dichroism can be laser induced and erased and this reversible birefringence and dichroism can be cycled many times without appearance of any fatigue and show a very good stability. On the basis of photo-induced optical blrefringence and dichroism, it is greatly anticipated that this polymer thin films bearing azo groups can be used as advanced materialsfor optical information storage.展开更多
采用水溶性偶氮引发剂V50和NaHSO3组成的复合引发剂,通过反相乳液聚合制备了相对分子质量高的聚丙烯酸钠。研究了引发剂种类及用量、乳化剂的HLB值及其用量、反应温度等因素对聚丙烯酸钠相对分子质量的影响规律。并采用正交优化方法对...采用水溶性偶氮引发剂V50和NaHSO3组成的复合引发剂,通过反相乳液聚合制备了相对分子质量高的聚丙烯酸钠。研究了引发剂种类及用量、乳化剂的HLB值及其用量、反应温度等因素对聚丙烯酸钠相对分子质量的影响规律。并采用正交优化方法对聚丙烯酸钠的聚合反应工艺进行优化研究。结果表明:复合引发剂V50/NaHS03效果优于APS/NaHSO3。最佳聚合工艺条件为复合乳化剂的用量为9%(占油相的质量百分数)、其HLB值为5.7、单体中和度为90%、引发剂用量为2.0%(占单体的质量百分数)、反应温度为40°C。在最佳反应条件下,得到的聚合物相对分子质量可达到2.1×107,溶解时间23 min(0.3 g/100 g H2O,45°C)。展开更多
In recent years, there has been a considerable research interest in moving-bed biofilm reactor（MBBR） for its efficiency and stability. This work proposes a new way to modify the hydrophilicity of polyurethane foam...In recent years, there has been a considerable research interest in moving-bed biofilm reactor（MBBR） for its efficiency and stability. This work proposes a new way to modify the hydrophilicity of polyurethane foam（PU） carriers via the layer-by-layer self-assembly of hyperbranched polymeric diazonium salt（M-HB-DAS） and poly（sodium-p-styrenesulfonate）（PSS）. Modified carriers showed very good adsorption for microbes according to the results of scanning electron microscope（SEM）. Biochemical experiments on wastewater treatment confirm that the modified PU carriers can improve the removal rate of chemical oxygen demand（COD）.展开更多
基金The financial support by the NSFC under Projects (Nos. 50533040, 20374033) is gratefully acknowledged.
文摘A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobic aggregation of the polymeric chains in THF-H2O dispersion media, which was induced by a steady increase in the water content. Results showed that the addition of a small amount of surfactant （SDBS） could significantly narrow the size distribution of the colloidal spheres. The size distribution of the colloidal spheres was determined by the concentrations of azo polymer and the amount of surfactant in the systems. When the concentrations of polymer and surfactant amount were in a proper range, colloidal spheres with narrow size distribution could be obtained. The colloidal spheres formed by this method could be elongated along the polarization direction of the laser beams to be a new type of the colloid-based functional materials. upon Ar^＋ laser irradiation. The colloidal spheres are considered
基金This work was supported by the National Natural Science Foundation of China （No.50573071, No.50533040, No.50703038, No.50773075, and No.50640420265）, the National Basic Research Program of China （No.2006cb302900）, and the Chinese Academy of Sciences （No.kjcx2.yw.H02）.
文摘Three series of amorphous copolymers containing azobenzene groups with various substituents and certain amounts of crosslinkable acrylic groups were prepared. The cross-linked polymer films were obtained by thermal polymerization of the acrylic groups in the copolymers, during which, by controlling the time of cross-linking reaction, the films can be made with different cross-linking degree （from 0 to 32%, which was monitored by FT-IR spectra measurement）. Photo-induced alignment process of the films was performed under irradiation with linearly polarized light at 442 nm, and the effect of cross-linking degree on the photo-induced alignment rate was investigated. The dynamics of the photo-induced alignment was analyzed with biexponential curve fitting. The photo-induced alignment rate and the maximum transmittance of the films decreased because of the cross-linking. Furthermore, for the cross-linked samples, it was found that their saturated value of transmittances keep constant after repeated ＂writing＂ and ＂erasing＂ cycles. The findings reveal that the cross-linking of the film can effectively restrain the phototactic mass transport of azopolymer during irradiation by polarized light. The relationship between the cross-linking degree and the photo-induced alignment behavior of azopolymer is discussed in detail.
文摘In this work, surface-relief-grating formation behavior was studied by using two hyperbranched azo polymers. The hyperbranched polymers containing pseudo-stilbene type azo chromophores throughout the hyperbranched structure were synthesized by step-growth polycondensation of AB2 type monomers. The AB2 monomer, 4-（4＇-（bis（2-chloroethyl）amino）- phenylazo）benzoic acid （BAA）, was prepared through azo-coupling reaction between N,N＇-bis（2-chloroethyl）aniline and 4- aminobenzenic acid. The another AB2 monomer, 4-（4＇-（bis（2-chloroethyl）amino）phenylazo）-3-nitro-benzoic acid （BANA）, was prepared through azo-coupling reaction between N,N-bis（2-chloroethyl）aniline and 3-nitro-4-aminobenzenic acid. The hyperbranched polymers （PBAA and PBANA） were prepared through nucleophilic substitution reaction of BAA and BANA, respectively. The polymers synthesized were characterized by using spectroscopic methods and thermal analysis. The photoinduced dichroism and photo-induced surface-relief-grating （SRG） formation of the hyperbranched polymers were investigated upon irradiation with Ar＋ laser at 488 nm. PBAA shows typical photoinduced dichroism SRG formation behavior. On the contrary, PBANA does not show the photoresponsive properties. The results indicate that the nitro at the ortho position of azo group of PBANA shows the effect of inhibiting the photoinduced variations. The effect can be attributed to the blockage of the trans-cis isomerization of the azobenzene moieties by the steric hindrance.
文摘Three epoxy-based azo polymers （PEP-AZ-C1, PEP-AZ-CN and PEP-AZ-NT） with high chromophore density were synthesized by using post-polymerization azo-coupling reactions between epoxy-based precursor polymer （PEP-AN） and diazonium salts of 4-chloroaniline, 4-aminobenzonitrile and 4-nitroaniline, respectively. The structures and properties of the azo polymers were characterized by using 1H-NMR, FT-IR, UV-Vis and thermal analyses. The photoinduced birefringence of the azo polymers was studied by irradiating spin-coated films of the polymers with laser beam at three different wavelengths （488, 532, and 589 nm）. The results indicate that the photoinduced birefringence of the azo polymers is related with the electron-withdrawing group on azo chromophores and the excitation wavelength. The excitation wavelength that can cause the efficient responses is determined by the absorption band positions of the a~：o chromophores, which are mainly affected by the electron-withdrawing group on the chromophores. Therefore, the,. azo polymers containing chromophores with different electron-withdrawing groups show different respon,;ive behavior to the irradiation light at different wavelengths. When irradiated with 488 nm light, PEP-AZ-Cl shows the shortest time to reach the saturated birefringence but with the lowest saturation birefringence level compared with the other two azo polymers. When irradiated with 532 nm light, PEP-AZ-CN shows the shortest time to reach the saturated birefringence. When irradiated with 532 and 589 nm light, PEP-AZ-NT shows the highest saturation birefringence level.
文摘A reversed duckweed polymeric LB film was fabricated by a new kind of amphiphilic polymer which was composed of hexanedlamine-epichlorohydrin slightly crosslinked hydrophilic network and hydrophobic chains conatining p-nitroazobenzene group. This amphiphilic polymer can form stable liquid-condensed monolayer and be transferred as Z-type polymeric LB films. This LB film combines the order and mobility and it has a well-estab- lished layer structure and azo chromphore is in an isotropic state in each layer. Optical birefringence and dichroism can be laser induced and erased and this reversible birefringence and dichroism can be cycled many times without appearance of any fatigue and show a very good stability. On the basis of photo-induced optical blrefringence and dichroism, it is greatly anticipated that this polymer thin films bearing azo groups can be used as advanced materialsfor optical information storage.
文摘采用水溶性偶氮引发剂V50和NaHSO3组成的复合引发剂,通过反相乳液聚合制备了相对分子质量高的聚丙烯酸钠。研究了引发剂种类及用量、乳化剂的HLB值及其用量、反应温度等因素对聚丙烯酸钠相对分子质量的影响规律。并采用正交优化方法对聚丙烯酸钠的聚合反应工艺进行优化研究。结果表明:复合引发剂V50/NaHS03效果优于APS/NaHSO3。最佳聚合工艺条件为复合乳化剂的用量为9%(占油相的质量百分数)、其HLB值为5.7、单体中和度为90%、引发剂用量为2.0%(占单体的质量百分数)、反应温度为40°C。在最佳反应条件下,得到的聚合物相对分子质量可达到2.1×107,溶解时间23 min(0.3 g/100 g H2O,45°C)。
基金Supported by the National Natural Science Foundation of China（Nos.21474056, 21674058）.
文摘In recent years, there has been a considerable research interest in moving-bed biofilm reactor（MBBR） for its efficiency and stability. This work proposes a new way to modify the hydrophilicity of polyurethane foam（PU） carriers via the layer-by-layer self-assembly of hyperbranched polymeric diazonium salt（M-HB-DAS） and poly（sodium-p-styrenesulfonate）（PSS）. Modified carriers showed very good adsorption for microbes according to the results of scanning electron microscope（SEM）. Biochemical experiments on wastewater treatment confirm that the modified PU carriers can improve the removal rate of chemical oxygen demand（COD）.
