阳离子型聚丙烯酰胺/十二烷基硫酸钠体系的研究

Study on Mixed Solution of Cationic Polyacrylamide and SDS

通过测量阳离子型聚丙烯酰胺/十二烷基硫酸钠(SDS)体系的动态表面张力、平衡表面张力及电导率,研究了聚丙烯酰胺的阳离子度的作用。聚电解质的阳离子度越大,溶液表面张力达到平衡所需的时间越短,平衡表面张力也越小。对于所研究的SDS浓度范围(<0.02mol·L-1),当聚丙烯酰胺浓度小于产生沉淀现象的浓度时,我们发现阳离子型聚丙烯酰胺/SDS溶液的电导率均比相应纯SDS水溶液的电导率大,且电导率随聚电解质离子度的增大而增加。结果表明,阳离子度即聚电解质链上的电荷数是降低SDS的表面张力、引起溶液电导率增大的主要因素。

The effect of the degree of charge of polyelectrolyte on the surface tension and the conductivity of sodium dodecyl sulfate （SDS） solution was studied. The dynamic and equilibrium surface tensions and conductivity of the dilute solutions of cationic polyacrylamide and SDS were measured with pendant drop tensiometer and conductometer, respectively. The concentration of SDS in the solution studied is in the range of 0 to 0.02 mol·L^-1 and that of polyelectrolyte is controlled to avoid precipitation. With the increase of the degree of charge of polyelectrolyte, the time is lesser for the surface tension to reach equilibrium and the equilibrium surface tension decreases. It manifests that the interaction between polyelectrolyte and surfactant increases with the increase of degree of charge of polyelectrolyte. The conductivity of aqueous polyelectrolyte/SDS solution is higher than that of pure SDS solution, and it increases with the increase of degree of charge ofpolyelectrolyte as well as the increase of concentration of polyelectrolyte. Results show that the degree of charge of polyelectrolyte, i.e. charge number on polyelctrolyte chain, plays key role in decreasing the surface tension and enhancing the conductivity of SDS solution.