The interaction of cetyl trimethylammonium bromide (CTAB)and an anionic copolymer derived from 3\|sulfopropylmethacrylate, potassium salt (SPMS) and styrene (St) in aqueous solutions has been studied. It was found tha...The interaction of cetyl trimethylammonium bromide (CTAB)and an anionic copolymer derived from 3\|sulfopropylmethacrylate, potassium salt (SPMS) and styrene (St) in aqueous solutions has been studied. It was found that the viscosity of the anionic copolymer\|CTAB solution rises suddenly in a specific molar ratio of CTAB/anion. For instance, the viscosity of polymer (No.1) solutions increases to about 20 times at CTAB/\|SO\-3K=1.0～1 05, and increases to about 100 times at CTAB/\|SO 3K=1.4～1 5. In the case of polymer samples No.2 and No.3, the changes of solution viscosity are similar to that of sample No.1, but the gelation takes place at CTAB/\|SO\-3K=1.4～1 5 region because of the lower negative charge density on No.2 and No.3 polymer chains. It is proposed that the dramatical change of the P(SPMS-co-St)/CTAB aqueous solution is ascribed to the aggregation behavior of CTAB, then the P(SPMS-co-St) aggregates. This consideration was verified by fluorescence determination and laser light scattering experiments. Using DMAF as fluoresscent probe, the hydrophobic microdomain existed in P(SPMS-co-St)/CTAB aqueous solutions in the viscosity rising region has been confirmed and it is in agreement well with the results obtained by laser light scattering determination.展开更多
Studies on the viscoelastic behavior of styrene- [ethylene-(ethylene-propylene)]-styrene block copolymer (SEEPS) were carried out, and some characteristic viscoelas-tic parameters were calculated. The longest relaxati...Studies on the viscoelastic behavior of styrene- [ethylene-(ethylene-propylene)]-styrene block copolymer (SEEPS) were carried out, and some characteristic viscoelas-tic parameters were calculated. The longest relaxation time τmax was obtained through simulating the relaxation spec-trum on the basis of a modified Baumgaertel-Schausberger- Winter (mBSW) model. The results revealed that there exists a “second plateau” in the low frequency region of the master curves. The reason for this phenomenon is attributed to the entanglement of macromolecular chains. It is suggested that the hard blocks, polystyrene, act as entanglement points, resulting in a topology restraint to the movement of macro-molecular chains. Meanwhile, it is found that the horizontal shift factors (aT) vs temperature in the master curve could be fitted to the Williams-Landel-Ferry (WLF) equation and Ar-rhenius equation respectively and the flow activation energy (Ea) is 127.88 kJ/mol. In addition, the plateau modulus (GN0) and entanglement molecule weight (Me) were calculated.展开更多
文摘The interaction of cetyl trimethylammonium bromide (CTAB)and an anionic copolymer derived from 3\|sulfopropylmethacrylate, potassium salt (SPMS) and styrene (St) in aqueous solutions has been studied. It was found that the viscosity of the anionic copolymer\|CTAB solution rises suddenly in a specific molar ratio of CTAB/anion. For instance, the viscosity of polymer (No.1) solutions increases to about 20 times at CTAB/\|SO\-3K=1.0～1 05, and increases to about 100 times at CTAB/\|SO 3K=1.4～1 5. In the case of polymer samples No.2 and No.3, the changes of solution viscosity are similar to that of sample No.1, but the gelation takes place at CTAB/\|SO\-3K=1.4～1 5 region because of the lower negative charge density on No.2 and No.3 polymer chains. It is proposed that the dramatical change of the P(SPMS-co-St)/CTAB aqueous solution is ascribed to the aggregation behavior of CTAB, then the P(SPMS-co-St) aggregates. This consideration was verified by fluorescence determination and laser light scattering experiments. Using DMAF as fluoresscent probe, the hydrophobic microdomain existed in P(SPMS-co-St)/CTAB aqueous solutions in the viscosity rising region has been confirmed and it is in agreement well with the results obtained by laser light scattering determination.
基金This work was supported by the National Science Foundation for Distinguished Young Scholars (Grant No.50125312) the National Natural Science Foundation of China (Grant No.50133020).
文摘Studies on the viscoelastic behavior of styrene- [ethylene-(ethylene-propylene)]-styrene block copolymer (SEEPS) were carried out, and some characteristic viscoelas-tic parameters were calculated. The longest relaxation time τmax was obtained through simulating the relaxation spec-trum on the basis of a modified Baumgaertel-Schausberger- Winter (mBSW) model. The results revealed that there exists a “second plateau” in the low frequency region of the master curves. The reason for this phenomenon is attributed to the entanglement of macromolecular chains. It is suggested that the hard blocks, polystyrene, act as entanglement points, resulting in a topology restraint to the movement of macro-molecular chains. Meanwhile, it is found that the horizontal shift factors (aT) vs temperature in the master curve could be fitted to the Williams-Landel-Ferry (WLF) equation and Ar-rhenius equation respectively and the flow activation energy (Ea) is 127.88 kJ/mol. In addition, the plateau modulus (GN0) and entanglement molecule weight (Me) were calculated.
