Ernst-Berl Institute for Chemical Engineering and Macromolecular Science, Technische Universität Darmstadt , Alarich-Weiss-Str. 4, D-64287 Darmstadt, Germany.
Langmuir. 2014 Jan 14;30(1):369-79. doi: 10.1021/la404004f. Epub 2013 Dec 23.
We present a strategy toward controlled polymer density in mesopores by specifically adjusting the local amount of polymerization initiator at the pore wall. The polymerization initiator concentration as well as the polymer functionalization has a direct impact on mesoporous membrane properties such as ionic permselectivity. Mesoporous silica-based thin films were prepared with specifically adjusted amount of polymerization initiator (4-(3-triethoxysilyl)propoxybenzophenone (BPSilane)) or initiator binding functions ((3-aminopropyl)triethoxysilane (APTES)), directly and homogeneously incorporated into the silica wall pursuing a sol-gel-based co-condensation approach. The amount of polymerization initiator was adjusted by varying its concentration in the sol-gel precursor solution. The surface chemistry, porosity, pore accessibility, and reactivity of the surface functional groups were investigated by using infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray reflectometry, ellipsometry, atomic force microscopy, and transmission electron microscopy. We could gradually modify the amount of reactive polymerization initiators in these mesoporous membranes. Mesopores were maintained for APTES containing films for all tested ratios up to 25 mol % and for BPSilane containing films up to 15 mol %. These films showed accessible and charge-dependent ionic permselectivity and an increasing degree of functionalization with increasing precursor ratio. This approach can directly result in control of polymer grafting density in mesoporous films and thus has a direct impact on applications such as the control of ionic transport through mesoporous silica membranes.
我们提出了一种通过在孔壁处特别调整聚合引发剂的局部量来控制介孔中聚合物密度的策略。聚合引发剂浓度以及聚合物官能化直接影响介孔膜的性质，例如离子选择性。通过溶胶-凝胶共缩合方法，将具有特定调整聚合引发剂（4-（3-三乙氧基硅基）丙氧基二苯甲酮（BPSilane））或引发剂结合官能团（（3-氨丙基）三乙氧基硅烷（APTES））的量直接且均匀地掺入到二氧化硅壁中，制备了基于介孔硅的薄膜。聚合引发剂的量通过改变其在溶胶-凝胶前驱体溶液中的浓度来调节。通过使用红外光谱、X 射线光电子能谱、X 射线反射率、椭圆光度法、原子力显微镜和透射电子显微镜研究了表面化学、孔隙率、孔可及性和表面官能团的反应性。我们可以逐渐改变这些介孔膜中反应性聚合引发剂的量。对于含 APTES 的薄膜，所有测试比例下的介孔都保持不变，高达 25 mol%，对于含 BPSilane 的薄膜，高达 15 mol%。这些薄膜显示出可及且电荷依赖性的离子选择性，并且随着前体比例的增加，官能化程度逐渐增加。这种方法可以直接控制介孔膜中聚合物接枝密度，从而直接影响通过介孔硅膜控制离子传输等应用。
