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首页> 外文期刊>Physical chemistry chemical physics: PCCP >Influence of surface functionalization on the hydrophilic character of mesoporous silica nanoparticles
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Influence of surface functionalization on the hydrophilic character of mesoporous silica nanoparticles

机译：表面功能化对介孔二氧化硅纳米粒子亲水特性的影响

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摘要

We report the synthesis and surface functionalization of MCM-41-like mesoporous silica nanoparticles (MSNs) with spheroidal shape and particle size of 141 +/- 41 nm. The success of surface functionalization with aminopropyl and sodium ethylcarboxylate groups (giving amino-MSN and carboxy-MSN, respectively) was ascertained by infrared spectroscopy and zeta potential measurements. The former showed the decrease of surface silanol groups and the corresponding appearance of signals related to NH2 bending mode (delta NH2) at 1595 cm(-1) and COO stretching (v(as) and v(sym)) at 1562 and 1418 cm(-1). The latter showed a change in surface charge, in that the isoelectric point (IEP) changed from pH 3-4.5 to 8.5 when the MSN was functionalized with the amino groups, while carboxy-MSN showed a more negative charge in the whole pH range with respect to MSN. The hydrophilic character of the prepared materials was ascertained by quantitative microgravimetric measurements, allowing the calculation of the average isosteric adsorption heat ((q) over bar (st)). This was found to be 51 +/- 3 kJmol(-1), 61 +/- 4, and 65 +/- 3 kJmol(-1) for MSN, amino-MSN, and carboxy-MSN samples, respectively. The increase in (q) over bar (st) after functionalization can be ascribed to the specific interaction of water molecules with the functionalizing agents, in agreement with a higher basicity with respect to silanol groups. Moreover, the possibility of multiple H-bonding interactions of water molecules with the carboxylate anion is put forward to account for the higher water uptake with respect to parent MSN.
机译：我们报告的合成和表面功能化的MCM 41状中孔二氧化硅纳米粒子（MSNs）与球形和141 +/- 41 nm的粒径。通过红外光谱法和ζ电势测定，确定了氨基丙基和乙基羧酸钠基团（分别赋予氨基-MSN和羧基-MSN）的表面功能化成功。前者在1595 cm（-1）处显示了表面硅烷醇基团的减少以及与NH2弯曲模式（δNH2）和在1562和1418 cm处的COO拉伸（v（as）和v（sym））有关的信号的相应外观（-1）。后者显示出表面电荷的变化，因为当MSN被氨基官能化时，等电点（IEP）从pH 3-4.5变为8.5，而羧基MSN在整个pH范围内显示出更多的负电荷。尊重MSN。通过定量的微重力测量确定所制备的材料的亲水性，从而可以计算平均等规吸附热（（q）/ bar（st））。对于MSN，氨基MSN和羧基MSN样品，这分别是51 +/- 3 kJmol（-1），61 +/- 4和65 +/- 3 kJmol（-1）。相对于硅烷醇基团具有较高的碱性，官能化后（q）相对于bar（st）的增加可以归因于水分子与官能化剂的特异性相互作用。此外，提出了水分子与羧酸根阴离子发生多次氢键相互作用的可能性，以解释相对于母体MSN较高的吸水率。

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