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
Hydroxypropyl methylcellulose acetate succinate(HPMCAS)was successfully synthesized from the reaction of hydroxypropyl methylcellulose with succinic anhydride and acetic anhydride in an acetone/pyridine system.Product...Hydroxypropyl methylcellulose acetate succinate(HPMCAS)was successfully synthesized from the reaction of hydroxypropyl methylcellulose with succinic anhydride and acetic anhydride in an acetone/pyridine system.Products with different contents of succinyl groups and acetyl groups were prepared by varying the reaction conditions.In the acetone/pyridine system,equipment corrosion does not occur,the product is easy to wash,and the solvent can be recycled.By varying the concentration of the esterifying agents,products with different ratios of acidic groups can be obtained.Under the optimum conditions,the obtained products had an average molecular weight between 5.39×104 and 5.41×104,a number average molecular weight from 4.97×104 to 5.13×104,and a polydispersity index from 1.05 to 1.08.The products dissolved well in acetone and methanol,and formed films on a mold.The films had good pH-sensitivity,tensile strength,and thermal stability.The formed films could dissolve in solutions with a pH value ranging from 5.4 to 6.4,and are therefore suitable for use as an enteric coating for pharmaceutical dosage forms.展开更多
Controlled and homogeneous flee-radical polymerization of acrylamide （AM） in aqueous phase was realized by using S,S＇-bis（α, α＇-dimethyl-α＂-acetic acid）-trithiocarbonate as a reversible addition-fragmentatio...Controlled and homogeneous flee-radical polymerization of acrylamide （AM） in aqueous phase was realized by using S,S＇-bis（α, α＇-dimethyl-α＂-acetic acid）-trithiocarbonate as a reversible addition-fragmentation transfer （RAFT） agent. Linear increases in molecular weight with conversion and narrow molecular weight distribution were observed for polyacrylamide （PAM） throughout the polymerization. By this method, PAMs with controlled molecular weight （up to 1.0 ~ 106） and narrow molecular weight distribution （Mw/Mn 〈 1.2） were prepared. This study provides an effective method for synthesis of PAMs with narrow molecular weight distribution under environmentally friendly conditions.展开更多
Near-infrared （NIR） persistent-luminescence nanoparticles have emerged as a new class of background-free contrast agents that are promising for in vivo imaging. The next key roadblock is to establish a robust and co...Near-infrared （NIR） persistent-luminescence nanoparticles have emerged as a new class of background-free contrast agents that are promising for in vivo imaging. The next key roadblock is to establish a robust and controllable method for synthesizing monodisperse nanoparticles with high luminescence brightness and long persistent duration. Herein, we report a synthesis strategy involving the coating/etching of the SiO2 shell to obtain a new class of small NIR highly persistent luminescent ZnGa2O4：Cr^3＋,Sn^4＋（ZGOCS） nanoparticles. The optimized ZGOCS nanoparticles have an excellent size distribution of -15 nm without any agglomeration and an NIR persistent luminescence that is enhanced by a factor of 13.5, owing to the key role of the SiO2 shell in preventing nanoparticle agglomeration after annealing. The ZGOCS nanoparticles have a signal-to-noise ratio -3 times higher than that of previously reported ZnGa204：Cr^3＋ （ZGC-1） nanoparticles as an NIR persistent-luminescence probe for in vivo bioimaging. Moreover, the persistent-luminescence signal from the ZGOCS nanoparticles can be repeatedly re-charged in situ with external excitation by a white light- emitting diode; thus, the nanopartides are suitable for long-term in vivo imaging applications. Our study suggests an improved strategy for fabricating novel high-performance optical nanoparticles with good biocompatibility.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The authors are grateful for the financial supports of this research from the Science and Technology Program of Guangdong(2019A1515011890)National Key R&D Program of China(2017YFD0601003).
文摘Hydroxypropyl methylcellulose acetate succinate(HPMCAS)was successfully synthesized from the reaction of hydroxypropyl methylcellulose with succinic anhydride and acetic anhydride in an acetone/pyridine system.Products with different contents of succinyl groups and acetyl groups were prepared by varying the reaction conditions.In the acetone/pyridine system,equipment corrosion does not occur,the product is easy to wash,and the solvent can be recycled.By varying the concentration of the esterifying agents,products with different ratios of acidic groups can be obtained.Under the optimum conditions,the obtained products had an average molecular weight between 5.39×104 and 5.41×104,a number average molecular weight from 4.97×104 to 5.13×104,and a polydispersity index from 1.05 to 1.08.The products dissolved well in acetone and methanol,and formed films on a mold.The films had good pH-sensitivity,tensile strength,and thermal stability.The formed films could dissolve in solutions with a pH value ranging from 5.4 to 6.4,and are therefore suitable for use as an enteric coating for pharmaceutical dosage forms.
文摘Controlled and homogeneous flee-radical polymerization of acrylamide （AM） in aqueous phase was realized by using S,S＇-bis（α, α＇-dimethyl-α＂-acetic acid）-trithiocarbonate as a reversible addition-fragmentation transfer （RAFT） agent. Linear increases in molecular weight with conversion and narrow molecular weight distribution were observed for polyacrylamide （PAM） throughout the polymerization. By this method, PAMs with controlled molecular weight （up to 1.0 ~ 106） and narrow molecular weight distribution （Mw/Mn 〈 1.2） were prepared. This study provides an effective method for synthesis of PAMs with narrow molecular weight distribution under environmentally friendly conditions.
文摘Near-infrared （NIR） persistent-luminescence nanoparticles have emerged as a new class of background-free contrast agents that are promising for in vivo imaging. The next key roadblock is to establish a robust and controllable method for synthesizing monodisperse nanoparticles with high luminescence brightness and long persistent duration. Herein, we report a synthesis strategy involving the coating/etching of the SiO2 shell to obtain a new class of small NIR highly persistent luminescent ZnGa2O4：Cr^3＋,Sn^4＋（ZGOCS） nanoparticles. The optimized ZGOCS nanoparticles have an excellent size distribution of -15 nm without any agglomeration and an NIR persistent luminescence that is enhanced by a factor of 13.5, owing to the key role of the SiO2 shell in preventing nanoparticle agglomeration after annealing. The ZGOCS nanoparticles have a signal-to-noise ratio -3 times higher than that of previously reported ZnGa204：Cr^3＋ （ZGC-1） nanoparticles as an NIR persistent-luminescence probe for in vivo bioimaging. Moreover, the persistent-luminescence signal from the ZGOCS nanoparticles can be repeatedly re-charged in situ with external excitation by a white light- emitting diode; thus, the nanopartides are suitable for long-term in vivo imaging applications. Our study suggests an improved strategy for fabricating novel high-performance optical nanoparticles with good biocompatibility.
