Qiu Dong, Cosgrove Terence, Howe Andrew M
School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
Langmuir. 2006 Jul 4;22(14):6060-7. doi: 10.1021/la060106t.
Small-angle neutron scattering was used to investigate the interactions in concentrated colloidal dispersions containing silica or polystyrene latex with adsorbed polyethyleneoxide (PEO). In these dispersions of charged particles, both electrostatic and steric repulsions are present. The PEO layer was made invisible to neutrons through contrast matching. The effect of the interparticle repulsion was clearly shown in the scattering spectra by the appearance of a peak at low Q. The effective potentials can be well described by the Hayter-Penfold/Yukawa (HPY) potential. In the silica dispersions studied, the layer thickness is small, hence the electrostatic potential dominates and the potential has a lower concentration dependence. In the dispersions of polystyrene latex, the adsorbed layer is thicker; consequently, the electrostatic potential dominates at low volume fraction (the potential has a lower concentration dependence), and the steric potential dominates at higher volume fraction (the potential has a higher concentration dependence). This study also suggests that when more than one potential is present the stronger one has a dominant influence in determining the structure factor. This finding makes it possible to describe the multicomponential interactions by a single function.
小角中子散射被用于研究含有二氧化硅或聚苯乙烯胶乳以及吸附的聚环氧乙烷（PEO）的浓胶体分散体系中的相互作用。在这些带电粒子分散体系中，同时存在静电排斥和空间位阻排斥。通过对比匹配使聚环氧乙烷层对中子不可见。粒子间排斥的影响在散射光谱中通过低Q处出现的一个峰清晰地显示出来。有效势可用海特 - 彭福尔德/汤川（HPY）势很好地描述。在所研究的二氧化硅分散体系中，层厚度较小，因此静电势占主导，且该势对浓度的依赖性较低。在聚苯乙烯胶乳分散体系中，吸附层较厚；因此，在低体积分数时静电势占主导（该势对浓度的依赖性较低），而在高体积分数时空间位阻势占主导（该势对浓度的依赖性较高）。该研究还表明，当存在不止一种势时，较强的势在决定结构因子方面具有主导影响。这一发现使得用单一函数描述多组分相互作用成为可能。
