Interactions between polyvinylpyrrolidone, sodium dodecylsulfate and nonylphenol ethoxylate in solution and on polystyrene particles
Journal article, 2007
Mixtures of polyvinylpyrrolidone (PVP), nonylphenol ethoxylate with, on the average, 84 oxyethylene units (NP 100) and sodium dodecylsulfate (SDS) in solution and on polystyrene particles are discussed in terms of various types of interaction according to their mutual affinities. The mixtures in solution were analyzed by means of NMR and static surface tension, which showed that the combination of SDS with PVP agreed well with the classical model with surfactant aggregates along the polymer chain. In the mixture with the nonionic surfactant NP100 and the anionic surfactant SDS, mixed micelles were formed with a strong attraction parameter beta = -5. 1. Evidence of SDS encapsulation in the NP100 micelle was obtained from NMR diffusometry data where the long and short residence times of SDS in the mixed micelle were estimated to be iota(A) = 2.19 s and TB = 0. 15 s, respectively. No interaction was found in a mixture between NP100 and PVP in solution. Upon adsorption of these component mixtures to a polystyrene surface, it was shown that complexes formed in solution also dominated at the surface. This applied both for the mixtures of SDS-PVP and of SDS-NP100, with the exception that the mixed micelles of SDS-NP100 seemed to have higher affinity than PVP to the surface. This was considered a result of the nonylphenol group in NP100. For the mixture of NP100 and PVP, the NP100 had a higher affinity to the surface than PVP, though both components were able to co-exist on the surface. Finally, as SDS, NP100 and PVP were adsorbed simultaneously, all three components seemed to adsorb, with a surface complex including SDS with, probably, both NP100 and PVP. In this three-component mixture a preferential adsorption of SDS and NP100 seemed to exist.