Notley Shannon M
Department of Applied Mathematics, Research School of Physical Sciences and Engineering, Australian National University, Canberra 0200 ACT, Australia.
Phys Chem Chem Phys. 2008 Apr 7;10(13):1819-25. doi: 10.1039/b718543j. Epub 2008 Feb 14.
The interaction between cellulose surfaces in aqueous solution has been measured using colloidal probe microscopy. Cellulose thin films with varying charge through carboxyl group substitution were used in this study with the surface forces fit to DLVO theory. It was found that the surface potential increased, as expected, with increasing carboxyl substitution. Furthermore, for a given degree of substitution, the surface potential increased as a function of increasing pH. At low pH, the surface forces interaction were attractive and could be fit to the non-retarded Hamaker equation using a constant of 3 x 10(-21) J. At pH greater than 5, the force interactions were monotonically repulsive, regardless of the ionic strength of the solution for all charge densities of the cellulose thin films. The adsorption of polyDADMAC to these charged cellulose films was also investigated using the quartz crystal microbalance. It was found that for the low charge film, a low surface excess of PDADMAC was sensed and that the adsorbed conformation was essentially flat. However for the higher charged cellulose film, a spontaneous de-swelling was observed resulting in no possibility of quantitatively determining the sensed mass using QCM.
利用胶体探针显微镜测量了水溶液中纤维素表面之间的相互作用。本研究使用了通过羧基取代而具有不同电荷的纤维素薄膜，并将表面力与DLVO理论进行拟合。结果发现，正如预期的那样，随着羧基取代度的增加，表面电位升高。此外，对于给定的取代度，表面电位随pH值的升高而增加。在低pH值下，表面力相互作用是吸引性的，并且可以使用3×10（-21）J的常数拟合到非延迟哈梅克方程。在pH值大于5时，无论纤维素薄膜所有电荷密度的溶液离子强度如何，力相互作用都是单调排斥的。还使用石英晶体微天平研究了聚二烯丙基二甲基氯化铵对这些带电纤维素薄膜的吸附。结果发现，对于低电荷薄膜，检测到的聚二烯丙基二甲基氯化铵表面过量较低，并且吸附构象基本是扁平的。然而，对于电荷较高的纤维素薄膜，观察到自发的去溶胀，导致无法使用石英晶体微天平定量测定检测到的质量。
