Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.
Langmuir. 2011 Jul 19;27(14):8718-28. doi: 10.1021/la200628a. Epub 2011 Jun 23.
Adsorption of anionic polyelectrolytes, sodium salts of carboxymethyl celluloses (CMCs) with different degrees of substitution (DS = 0.9 and 1.2), from aqueous electrolyte solutions onto regenerated cellulose surfaces was studied using quartz crystal microbalance with dissipation monitoring (QCM-D) and surface plasmon resonance (SPR) experiments. The influence of both calcium chloride (CaCl(2)) and sodium chloride (NaCl) on CMC adsorption was examined. The QCM-D results demonstrated that CaCl(2) (divalent cation) caused significantly greater CMC adsorption onto regenerated cellulose surfaces than NaCl (monovalent cation) at the same ionic strength. The CMC layers adsorbed onto regenerated cellulose surfaces from CaCl(2) solutions exhibited greater stability upon exposure to flowing water than layers adsorbed from NaCl solutions. Both QCM-D and SPR results showed that CMC adsorption onto regenerated cellulose surfaces from CaCl(2) solutions increased with increasing CaCl(2) concentration up to the solubility limit (10 mM). Voigt-based viscoelastic modeling of the QCM-D data indicated that the CMC layers adsorbed onto regenerated cellulose surfaces had shear viscosities of η(f) ≈ 10(-3) N·s·m(-2) and elastic shear moduli of μ(f) ≈ 10(5) N·m(-2). Furthermore, the combination of SPR spectroscopy and QCM-D showed that the CMC layers contained 90-95% water. Adsorption isotherms for CMCs in CaCl(2) solutions were also obtained from QCM-D and were fit by Freundlich isotherms. This study demonstrated that CMC adsorption from CaCl(2) solutions is useful for the modification of cellulose surfaces.
采用石英晶体微天平（QCM-D）和表面等离子体共振（SPR）实验，研究了不同取代度（DS=0.9 和 1.2）的羧甲基纤维素钠盐（CMC）从水溶液中在再生纤维素表面上的吸附。研究了氯化钙（CaCl 2 ）和氯化钠（NaCl）对 CMC 吸附的影响。QCM-D 结果表明，在相同离子强度下，二价阳离子 CaCl 2 （氯化钙）引起的 CMC 在再生纤维素表面上的吸附量显著大于单价阳离子 NaCl（氯化钠）。与从 NaCl 溶液中吸附的 CMC 层相比，从 CaCl 2 溶液中吸附到再生纤维素表面的 CMC 层在暴露于流动水时具有更大的稳定性。QCM-D 和 SPR 结果均表明，从 CaCl 2 溶液中吸附到再生纤维素表面的 CMC 随 CaCl 2 浓度的增加而增加，直至达到溶解度极限（10 mM）。基于 Voigt 的 QCM-D 数据的粘弹性建模表明，从 CaCl 2 溶液中吸附到再生纤维素表面的 CMC 层的剪切粘度 η(f)≈10 -3 N·s·m -2 ，弹性剪切模量 μ(f)≈10 5 N·m -2 。此外，SPR 光谱和 QCM-D 的组合表明 CMC 层含有 90-95%的水。还从 QCM-D 获得了 CMC 在 CaCl 2 溶液中的吸附等温线，并通过 Freundlich 等温线进行拟合。该研究表明，从 CaCl 2 溶液中吸附 CMC 可用于修饰纤维素表面。
