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
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 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
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
In this contribution,we utilized surface initiated atom transfer radical polymerization(SI-ATRP)to prepare organicinorganic hybrid core/shell silila nanoparticles(NPs),where silia particles acted as cores and polymeri...In this contribution,we utilized surface initiated atom transfer radical polymerization(SI-ATRP)to prepare organicinorganic hybrid core/shell silila nanoparticles(NPs),where silia particles acted as cores and polymeric shells(PAzoMA*)were attached to silica particles via covalent bond.Subsequently,chiroptical switch was sccessfully constructed on silica NPs surface taking advantage of supramolecular chiral self-assembly of the grafted side chain Azo-containing polymer(PAzoMA*).We found that the supramolecular chirality was highly dependent on the molecular weight of grafted PAzoMA*.Meanwhile,the supramolecular chirality could be regulated using 365 nm UV light iradiation and heating cooling treatment,and a reversible supramolecular chiroptical switch could be repeated for over five cycles on silia NPs surface.Moreover,when heated above the glass transition temperature(T_(g))of PAzoMA",the organic-inorganic hybrid nanoparticles(SiO_(2)@PAzoMA*NPs)still exhibited intense DRCD signals.Interestingly,the supramolecular chirality could be retained in solid film for more than 3 months.To conclude,we have prepared an organic inorganic hybrid core/shell chiral slia nanomaterial with dynamic reversible chirality,thermal stability and chiral storage functions,providing potential applications in dynamic asymmetric catalysis,chiral separation and so on.展开更多
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.
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.
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by the National Natural Science Foundation of China(Nos.21971180 and 92056111)Natural Science Key Basic Research of Jiangsu Province for Higher Education(No.19KJA360006)+2 种基金Postgraduate Research&Practice Innovation Program of Jiangsu Provinee(No.KYCX20_2655)College Students'Innovation and Entrepreneurship Program(No.201910285021Z)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions and the Program of Innovative Research Team of Soochow University.Prof.W.Zhang thanks Mr.J.Z.Wang in University of Waterloo for English editing.
文摘In this contribution,we utilized surface initiated atom transfer radical polymerization(SI-ATRP)to prepare organicinorganic hybrid core/shell silila nanoparticles(NPs),where silia particles acted as cores and polymeric shells(PAzoMA*)were attached to silica particles via covalent bond.Subsequently,chiroptical switch was sccessfully constructed on silica NPs surface taking advantage of supramolecular chiral self-assembly of the grafted side chain Azo-containing polymer(PAzoMA*).We found that the supramolecular chirality was highly dependent on the molecular weight of grafted PAzoMA*.Meanwhile,the supramolecular chirality could be regulated using 365 nm UV light iradiation and heating cooling treatment,and a reversible supramolecular chiroptical switch could be repeated for over five cycles on silia NPs surface.Moreover,when heated above the glass transition temperature(T_(g))of PAzoMA",the organic-inorganic hybrid nanoparticles(SiO_(2)@PAzoMA*NPs)still exhibited intense DRCD signals.Interestingly,the supramolecular chirality could be retained in solid film for more than 3 months.To conclude,we have prepared an organic inorganic hybrid core/shell chiral slia nanomaterial with dynamic reversible chirality,thermal stability and chiral storage functions,providing potential applications in dynamic asymmetric catalysis,chiral separation and so on.
