A novel radical grafting copolymerization process has been designed for water-soluble polymers which avoids the problems of conducting grafting reactions in highly viscous polymerization media. A variety of water-solu...A novel radical grafting copolymerization process has been designed for water-soluble polymers which avoids the problems of conducting grafting reactions in highly viscous polymerization media. A variety of water-soluble graft copolymers having starch or dextran as the backbone chain with grafted side chains of polyacrylamide (—AM—), poly (acrylic acid ) (—AA—), poly (acrylamide-co-acrylic acid) (—AM—NH_4AA—) or poly ( acrylamide-co-2-acryiamido-2-methyl-l-propanesulphinic acid) (—AM—AMPS—) have been synthesized in gel droplets using aceric sulphate redox initiator, and their properties compared. The reaction conditions were optimized taking into account reaction kinetic data and the observed properties of the products produced under different reaction conditions. The effects of the ratios of [backbone]/[graft monomer], [ AM]/[ AA]/[AMPS] , [Ce^(4+)]/[ S_2O_8=] and pH value on the reaction rate , conversion, grafting degree, grafted chain length and the product molecular weight have been investigated.展开更多
The chemical modification of the surface of calcium alginate gel beads (CAGB) via grafting copolymerization with vinyl acetate (VAc) was studied. The optimum reaction conditions with activation and graft copolymerizat...The chemical modification of the surface of calcium alginate gel beads (CAGB) via grafting copolymerization with vinyl acetate (VAc) was studied. The optimum reaction conditions with activation and graft copolymerization two steps were explored. First, 5 grams CAGB with 2.5 mm initial diameter was initiated with 0.0493 mol/L K2S2O8 at 51 °C for 30 min in 15 mL 1 % PVA/H2O. Then 4.34 moi/L VAc was added dropwise and the reaction was allowed to proce at 48 °C for 3 h. The grafting efficiency could come up to 30%. It was found the stability of modified CAGB in the air and in electrolyte solutions was greatly improved.展开更多
The calcium alginate gel beads（CAGB） are modified via graft copolymerization with acrylonitrile（AN）. It is found that the grafting yield achieved 799% when 5.0 g CAGB（in diameter of 3.2 mm） is mixed with 0.033 9...The calcium alginate gel beads（CAGB） are modified via graft copolymerization with acrylonitrile（AN）. It is found that the grafting yield achieved 799% when 5.0 g CAGB（in diameter of 3.2 mm） is mixed with 0.033 9 mol/L K2S2O8 for 35 min at 51 ℃ and copolymerized with 2.85 mol/L AN for 4 h. The structure of CAGB-g-PAN is verified with FTIR. The compactness of CAGB and modified CAGB is investigated with fluorometry. It is found that the compactness of the gel beads is increased with the grafting yield. Modified CAGBs keep their integrity in the electrolyte solutions that are capable of decomposition of CAGB, indicating the stability of CAGB is greatly enhanced.展开更多
文摘A novel radical grafting copolymerization process has been designed for water-soluble polymers which avoids the problems of conducting grafting reactions in highly viscous polymerization media. A variety of water-soluble graft copolymers having starch or dextran as the backbone chain with grafted side chains of polyacrylamide (—AM—), poly (acrylic acid ) (—AA—), poly (acrylamide-co-acrylic acid) (—AM—NH_4AA—) or poly ( acrylamide-co-2-acryiamido-2-methyl-l-propanesulphinic acid) (—AM—AMPS—) have been synthesized in gel droplets using aceric sulphate redox initiator, and their properties compared. The reaction conditions were optimized taking into account reaction kinetic data and the observed properties of the products produced under different reaction conditions. The effects of the ratios of [backbone]/[graft monomer], [ AM]/[ AA]/[AMPS] , [Ce^(4+)]/[ S_2O_8=] and pH value on the reaction rate , conversion, grafting degree, grafted chain length and the product molecular weight have been investigated.
基金This work was supported by the Young Scientist & Technician Creation Item sponsored by Fujian Province (No. 2002J021)and Scientific Research Fund Sponsored by Huaqiao University.
文摘The chemical modification of the surface of calcium alginate gel beads (CAGB) via grafting copolymerization with vinyl acetate (VAc) was studied. The optimum reaction conditions with activation and graft copolymerization two steps were explored. First, 5 grams CAGB with 2.5 mm initial diameter was initiated with 0.0493 mol/L K2S2O8 at 51 °C for 30 min in 15 mL 1 % PVA/H2O. Then 4.34 moi/L VAc was added dropwise and the reaction was allowed to proce at 48 °C for 3 h. The grafting efficiency could come up to 30%. It was found the stability of modified CAGB in the air and in electrolyte solutions was greatly improved.
文摘The calcium alginate gel beads（CAGB） are modified via graft copolymerization with acrylonitrile（AN）. It is found that the grafting yield achieved 799% when 5.0 g CAGB（in diameter of 3.2 mm） is mixed with 0.033 9 mol/L K2S2O8 for 35 min at 51 ℃ and copolymerized with 2.85 mol/L AN for 4 h. The structure of CAGB-g-PAN is verified with FTIR. The compactness of CAGB and modified CAGB is investigated with fluorometry. It is found that the compactness of the gel beads is increased with the grafting yield. Modified CAGBs keep their integrity in the electrolyte solutions that are capable of decomposition of CAGB, indicating the stability of CAGB is greatly enhanced.
