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采用毛细管法和荧光探针法研究了疏水缔合聚合物在不同甲酰胺浓度和盐浓度的溶剂中的特性黏数和疏水缔合作用强度.找到可以消除缔合作用和聚电解质效应的溶剂条件,用静态光散射法测定疏水缔合聚合物的重均分子量.结果表明,NaCl能够有效的屏蔽聚电解质效应,但是不能消除缔合作用,而且由于NaCl增加了溶液的极性,会进一步促进疏水缔合作用,疏水缔合聚合物以聚集体形态存在溶液中,因此,在NaCl溶剂中测得的疏水缔合聚合物的重均分子量不是真实分子量;而甲酰胺可以完全破坏疏水缔合作用,使聚合物分子以单分子态分散在溶液中,进而测得疏水缔合聚合物的真实分子量.当溶剂中的NaCl浓度为0.2 mol/L、甲酰胺体积分数为50%时,可准确测定疏水缔合聚合物的重均分子量.当缔合作用消除后再改变甲酰胺浓度,测得的重均分子量不再变化;聚电解质效应消除后,盐离子浓度的变化不会再改变测得的重均分子量结果.
The intrinsic viscosity and hydrophobic interaction strength of hydrophobic association polymers in solvents with different formamide concentrations and salt concentrations were studied by capillary and fluorescence probe methods. Solvent conditions were found to eliminate association and polyelectrolyte effects , The weight average molecular weight of the hydrophobically associating polymer was determined by static light scattering method.The results showed that NaCl could effectively shield the polyelectrolyte effect but could not eliminate the association effect and further promote the hydrophobicity due to the increase of the polarity of the solution by NaCl Therefore, the weight-average molecular weight of the hydrophobically associating polymer measured in NaCl solvent is not the true molecular weight; whereas formamide completely destroys the hydrophobic association, So that the polymer molecules dispersed in solution in a single molecular state, and then measured the true molecular weight of the hydrophobic association polymer.When the concentration of NaCl in the solvent 0.2 mol / L, formamide volume fraction of 50%, accurate determination of hydrophobic The weight average molecular weight of the associative polymer.When the association effect is eliminated and then change the concentration of formamide, the measured weight average molecular weight no longer changes; polyelectrolyte effect is eliminated, Changes in ion concentration will not change the weight average molecular weight measured results.