Well-defined homo glycopolymer/montmorillonite (MMT) nanocomposite (gly1) was prepared successfully by the “grafting from” technique from the modified surface of MMT via surface initiated atom transfer radical polym...Well-defined homo glycopolymer/montmorillonite (MMT) nanocomposite (gly1) was prepared successfully by the “grafting from” technique from the modified surface of MMT via surface initiated atom transfer radical polymerization (SI-ATRP) of 3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-α-D-glucofuranose (gly) in the presence of Cu(I)Br/ bi- pyridyl at 90?C in xylene. Well-defined diblock copolymers (gly2, gly3, gly4 and gly5) were also synthesized via the same technique by using comonomers of methylmethacrylate (MMA) or styrene (St) with glycomonomer (gly) using the same catalytic system. The formed nanocomposites showed both intercalated and exfoliated structures, as judged by XRD and TEM measurements. Further analyses were performed on such nanocomposites to confirm their formation such as TGA and DSC. The structures of the attached polymers to MMT were characterized by 1H NMR.展开更多
Nanocomposites with various contents of organophilic montmorillonite (oMMT) have been prepared by adding oMMT to interpenetrating poly- mer networks (IPNs) of polyurethane and epoxy resin (PU/EP) which had been prepar...Nanocomposites with various contents of organophilic montmorillonite (oMMT) have been prepared by adding oMMT to interpenetrating poly- mer networks (IPNs) of polyurethane and epoxy resin (PU/EP) which had been prepared by a sequential polymeric technique. DSC experiment indicates a novel phenomenon that the glass transition tem- perature (Tg) of the nanocomposites increases with the oMMT content up to 3 %, then decreases with further increasing oMMT content. In order to explain this phenomenon, crosslink density, hydrogen bond- ing in the hard segments, crystallization of the nanocomposites and the exfoliation degree of oMMT in the nanocomposites have been investigated by swelling method, FT-IR, XRD, SEM and TEM, re- spectively. The results indicate that the crosslink density and the hydrogen bonding index of the nanocomposites increase, but the crystallization de- gree of the nanocomposites decreases with increas- ing oMMT content. In addition, oMMT improves the network structure of PU/EP.展开更多
Polymer/clay nanocomposite films were prepared by means of electrodeposition of aqueous suspension including cathodic electrophoretic acrylic resin (CEAR) and Na+-montmorillonite (NMMT). Studies of XRD,SEM and TEM ind...Polymer/clay nanocomposite films were prepared by means of electrodeposition of aqueous suspension including cathodic electrophoretic acrylic resin (CEAR) and Na+-montmorillonite (NMMT). Studies of XRD,SEM and TEM indicated well-dispersed NMMT platelets in the films prepared. The ideal dispersity achieved was thought to be the result of aqueous compatibility between CEAR molecules and NMMT platelets and the result of the water-involved process as well. The modulus and strength of the polymer/clay nanocomposite coatings tested by tensile testing and nano-indentation were effectively improved compared to those of the virgin CEAR film. In addition,the adhesion strength,flexibility and water-resistance represented by Chinese national standard (GB) kept the best grades.展开更多
文摘Well-defined homo glycopolymer/montmorillonite (MMT) nanocomposite (gly1) was prepared successfully by the “grafting from” technique from the modified surface of MMT via surface initiated atom transfer radical polymerization (SI-ATRP) of 3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-α-D-glucofuranose (gly) in the presence of Cu(I)Br/ bi- pyridyl at 90?C in xylene. Well-defined diblock copolymers (gly2, gly3, gly4 and gly5) were also synthesized via the same technique by using comonomers of methylmethacrylate (MMA) or styrene (St) with glycomonomer (gly) using the same catalytic system. The formed nanocomposites showed both intercalated and exfoliated structures, as judged by XRD and TEM measurements. Further analyses were performed on such nanocomposites to confirm their formation such as TGA and DSC. The structures of the attached polymers to MMT were characterized by 1H NMR.
文摘Nanocomposites with various contents of organophilic montmorillonite (oMMT) have been prepared by adding oMMT to interpenetrating poly- mer networks (IPNs) of polyurethane and epoxy resin (PU/EP) which had been prepared by a sequential polymeric technique. DSC experiment indicates a novel phenomenon that the glass transition tem- perature (Tg) of the nanocomposites increases with the oMMT content up to 3 %, then decreases with further increasing oMMT content. In order to explain this phenomenon, crosslink density, hydrogen bond- ing in the hard segments, crystallization of the nanocomposites and the exfoliation degree of oMMT in the nanocomposites have been investigated by swelling method, FT-IR, XRD, SEM and TEM, re- spectively. The results indicate that the crosslink density and the hydrogen bonding index of the nanocomposites increase, but the crystallization de- gree of the nanocomposites decreases with increas- ing oMMT content. In addition, oMMT improves the network structure of PU/EP.
基金Supported by the National Natural Science Foundation of China (Grant No. 50572044)the 973 Project (Grant No. 2006CB605207-2)
文摘Polymer/clay nanocomposite films were prepared by means of electrodeposition of aqueous suspension including cathodic electrophoretic acrylic resin (CEAR) and Na+-montmorillonite (NMMT). Studies of XRD,SEM and TEM indicated well-dispersed NMMT platelets in the films prepared. The ideal dispersity achieved was thought to be the result of aqueous compatibility between CEAR molecules and NMMT platelets and the result of the water-involved process as well. The modulus and strength of the polymer/clay nanocomposite coatings tested by tensile testing and nano-indentation were effectively improved compared to those of the virgin CEAR film. In addition,the adhesion strength,flexibility and water-resistance represented by Chinese national standard (GB) kept the best grades.
