Ian Wark Research Institute, ARC Special Research Centre for Particles and Material Interfaces, University of South Australia, Mawson Lakes, SA 5095, Australia.
Langmuir. 2012 Mar 6;28(9):4233-40. doi: 10.1021/la204652f. Epub 2012 Feb 22.
The adsorption of two dextrin-based polymers, a regular wheat dextrin (TY) and a carboxymethyl-substituted (CM) dextrin, onto an anatase TiO(2) particle film has been studied using in situ attenuated total reflection (ATR) FTIR spectroscopy. Infrared spectra of the polymer solutions and the polymer adsorbed at the anatase surface were acquired for two solution conditions: pH 3 and pH 9; below and above the isoelectric point (IEP) of anatase, respectively. Comparison of the polymer solution spectra and the adsorbed layer spectra highlighted a number of spectral differences that were attributed to involvement of the carboxyl group of CM Dextrin interacting with the anatase surface directly and the adsorption of oxidized dextrin chains in the case of regular dextrin (TY) at high pH. The adsorption/desorption kinetics were determined by monitoring spectral peaks of the pyranose ring of both polymers. Adsorption equilibrium was not established for Dextrin TY for many hours, whereas CM Dextrin reached equilibrium in its adsorption within 60 min. The extent of desorption of Dextrin TY (observed by flowing a background electrolyte dextrin-free solution) was extensive at both pH values, which reflects the poor affinity and binding of the polymer on anatase. In contrast, CM Dextrin underwent almost no desorption, indicating a high affinity between the carboxyl groups of the polymer and the anatase surface.
使用原位衰减全反射（ATR）FTIR 光谱研究了两种直链淀粉基聚合物，即普通小麦直链淀粉（TY）和羧甲基取代（CM）直链淀粉，在锐钛矿 TiO(2)颗粒膜上的吸附情况。在两种溶液条件下获得了聚合物溶液和吸附在锐钛矿表面的聚合物的红外光谱：pH 3 和 pH 9；分别低于和高于锐钛矿的等电点（IEP）。将聚合物溶液光谱与吸附层光谱进行比较，突出了许多光谱差异，这些差异归因于 CM 直链淀粉的羧基直接与锐钛矿表面相互作用，以及在高 pH 下，氧化直链淀粉链的吸附，而对于普通直链淀粉（TY）则是如此。通过监测两种聚合物吡喃糖环的光谱峰来确定吸附/解吸动力学。对于直链淀粉 TY，吸附平衡在数小时内未达到，而 CM 直链淀粉在 60 分钟内达到吸附平衡。在两种 pH 值下，直链淀粉 TY 的解吸程度都很广泛，这反映了聚合物在锐钛矿上的亲和力差和结合不牢。相比之下，CM 直链淀粉几乎没有解吸，表明聚合物的羧基与锐钛矿表面之间具有很高的亲和力。
