基于丙烯酸的聚电解质与聚乙二醇溶液的粘度行为

Viscosity Behavior of Solution of Acrylic-acid-based Polyelectrolyte and Poly( ethylene glycol)

报道不同温度下PEG-PAA-C2H5OH-H2O体系的相图,以及质量分数、温度、PEG摩尔分数、Na Cl和尿素对中和度分别为50%的PAA(DN-50%)和100%的PAANa及其与PEG构成的复合体系的粘度行为的影响.结果表明,PAA线团内氢键作用形成羧基"桥架"结构、柔性带疏水结构的PEG分子的缠绕作用以及乙醇分子对大分子间作用力的消弱作用共存;与PAANa比较,PAA(DN-50%)因受羧基"桥架"结构影响,质量分数对其比浓粘度影响较小;PEG分子对PAA(DN-50%)和PAANa的缠绕模式不同,在PEG摩尔分数小于0.5的情况下,复合体系的比浓粘度变化趋势不同;聚合物链段的内能随温度升高而增大,溶液的比浓粘度降低;主要由于同离子效应缘故,随Na Cl质量分数增加,2种复合体系比浓粘度都降低;尿素分子在PAA(DN-50%)线团表面因氢键结合及水化,使得复合体系PEG+PAA(DN-50%)的比浓粘度在尿素质量分数低于0.25%时随质量分数增大有所增加;当质量分数超过0.25%后,进入聚合物线团的尿素分子因其氢键作用使得线团收缩,比浓粘度降低.

This paper reports the phase diagram of PEG-PAA-C2 H5 OH-H2O system at different temperatures and the effects of con- centration, temperature, PEG molar ratio, NaCl and Urea on viscosity behavior of PAA （DN-50%）, which are from PAA with 50% carboxyl group neutralized, PAANa and their composite with PEG. The results show that the relatively stable ＂carboxyl bridges＂ formed by the internal hydrogen bonding of PAA chain coils, the entanglement effect of PEG with hydrophobic structure in inflexible chain and the effect of ethanol on extinction of intermolecular forces are coexisting. Compared with PAANa, the effect of concentration of PAA（ DN-50% ） on its specific viscosity has less impact because of the ＂carboxyl bridges＂ effect. The change trends of specific vis- cosity of composites are different when PEG is below the molar ratio of 0.5 for the difference of the winding mode of PEG to PAA（ DN- 50% ） and PAANa. The internal energy of the chain segments increases with the increase of temperature so that the specific viscosity of the solution decreases correspondingly. Mainly due to the same ion effect, the specific viscosities of the two kinds of composite solutions decrease with the increase of the NaC1 concentration. Hydrogen bonding and hydration of urea molecules on the surface of PAA （ DN- 50% ） coil lead to the increasing of the specific viscosity of composite PEG ＋ PAA（ DN-50% ） with increasing the urea concentration when the urea concentration is below 0.25%. When the concentration of urea exceeds 0.25%, the polymer coils shrink and the specific viscosities decrease because of the hydrogen bonding interactions between urea molecules in the polymer coils and carboxyl group.