聚苯乙烯磺酸钠在1-烯丙基-3-甲基咪唑氯盐中的流变行为

Rheological Behaviors of Sodium Polystyrene Sulfonate in 1-Allyl-3-methylimidazolium Chloride

研究了聚苯乙烯磺酸钠(Na PSS)在1-烯丙基-3-甲基咪唑氯盐(AmimCl)中的流变行为,并与其在AmimCl/H_2O混合溶剂中的流变行为进行了对比.聚合物浓度单位为每升溶剂中所含链段单元的摩尔数(mol/L).研究发现,Na PSS在AmimCl中表现出与其在无盐、有盐水溶液以及中性聚合物在离子液体(ILs)溶液中不同的流变行为.Na PSS在AmimCl含量不同的AmimCl/H_2O混合溶剂中的流变行为也不相同,随着AmimCl含量的增加,Na PSS在混合溶剂中的特性黏数[η]逐渐降低,表明分子线团逐渐塌缩,溶液的增比黏度随Na PSS浓度变化的标度所表现出的性质由聚电解质无盐水溶液特点逐渐变为中性聚合物溶液在θ状态下特点.当溶剂为纯AmimCl时,0.007~0.8 mol/L的浓度范围在0.29 mol/L处被分成2个浓度区.动态流变行为研究表明c<0.29 mol/L浓度区为稀溶液区,溶液的增比黏度和弛豫时间随Na PSS浓度变化的标度关系为:ηsp^c1.4p和τ~c0p,与无盐聚电解质水溶液在缠结区的行为相似;c>0.29 mol/L浓度区为溶液的亚浓非缠结区,溶液在该浓度区内增比黏度和弛豫时间随Na PSS浓度变化的标度关系为:ηsp^c3.5p和τ~c1.9p,接近于中性聚合物良溶液在亚浓缠结区的行为.这一特殊现象可能由混合体系中强烈的长程静电耦合作用引起.

Effect of electrostatic interactions between these the chain conformation and the rheological behavior is ions and the charged monomer of polyelectrolyte on a fundamentally important issue for engineering application of polyelectrolyte/ILs systems. Rheological behavior of a polyelectrolyte, sodium polystyrene sulfonate （NaPSS） ,in 1-allyl-3-methylimidazolium chloride （AmimC1） has been investigated and compared to that in AmimC1/H20 co-solvent solutions. Mole of chain segment unit per liter （mol/L） is used to define the concentration of NaPSS. The results show that, NaPSS in AmimC1 solution shows different rheological behaviors from which in salt-free aqueous solution, added salt aqueous solution and neutral polymer in ionic liquid solution. Rheological behaviors of NaPSS in AmimC1/H2O co-solvent solutions are also different from each other. With increasing AmimCl concentration, intrinsic viscosity [η] of NaPSS in AmimCl/H2O decreases, indicating the decline of chain coil size of NaPSS. NaPSS in AmimCl/H20 co-solvent show the rheological behaviors changing from salt-free polyelectrolyte solution to neutral polymer in 0 solvent with increasing AmimC1 concentration. When the solvent changes into pure AmimC1, NaPSS in AmimC1 solution is divided into two concentration regimes in the range from 0. 007 NaPSS chain does not overlap in the concentration mol/L to 0.8 mol/L. Dynamic frequency sweep shows that regime bellow 0.29 mol/L, where the power laws for the concentration dependence of specific viscosity and terminal relaxation time are ηp - c1.4 p and r - cp 0, respectively,similar to theoretical prediction for salt-free polyelectrolyte solutions in entangled regime. The concentration regime above 0.29 mol/L is considered as semidilute un-entangled regime,where the power laws for the concentration dependence of specific viscosity and terminal relaxation time are ηp - c3p5 and - c1.9 p, respectively, closing to theoretical prediction for neutral polymer in good solvents in entangled regime. The unique phenomenon may be caused by the high electrostatic coupling of monomer-ion and monomer-monomer.