Department of Chemistry, University at Buffalo, SUNY, Buffalo, NY 14260-3000, USA.
Anal Chim Acta. 2013 Jun 27;785:98-103. doi: 10.1016/j.aca.2013.04.052. Epub 2013 May 6.
We describe a novel and generally applicable approach for creating voids in films deposited on the surface of solid substrates. Such films are advantageous when a quartz crystal microbalance (QCM) is the basis of a sensor. We show that films with large void volumes produce more sensitive sensors than with the original film. Poly(methylmethacrylate) (PMMA) was used as the polymer layer deposited on a quartz crystal microbalance (QCM) to demonstrate our technique for the model system of water vapor analysis in flowing nitrogen gas. A film of pure PMMA on a QCM is a sensor for water vapor in a gas phase. A more sensitive sensor was created by dip coating QCM crystals into solutions containing mixtures of PMMA and poly(D,L-lactide) (PDLL) and then evaporating the solution films on the QCM crystals to form mixed polymer films of varying PDLL content. The PDLL was then removed from the mixed polymer films by exposure to a NaOH solution to form pure PMMA films having various void volumes. A leached PMMA film that originally contained 50% by weight PDLL had a 3.7 times larger QCM sensitivity for water vapor than a pure PMMA film.
我们描述了一种新颖且普遍适用的方法，用于在固体基底表面沉积的薄膜中制造空隙。当石英晶体微天平 (QCM) 是传感器的基础时，这种薄膜是有利的。我们表明，具有大空隙体积的薄膜比原始薄膜产生更灵敏的传感器。聚甲基丙烯酸甲酯 (PMMA) 被用作沉积在石英晶体微天平 (QCM) 上的聚合物层，以展示我们用于在流动氮气中分析水蒸气的模型系统的技术。在气相中，纯 PMMA 的薄膜是水蒸气的传感器。通过将 QCM 晶体浸入含有 PMMA 和聚 (D,L-丙交酯) (PDLL) 混合物的溶液中，然后在 QCM 晶体上蒸发溶液薄膜，形成具有不同 PDLL 含量的混合聚合物薄膜，从而创建了更灵敏的传感器。然后将 PDLL 从混合聚合物薄膜中去除，通过暴露于 NaOH 溶液形成具有各种空隙体积的纯 PMMA 薄膜。最初含有 50%重量 PDLL 的浸出 PMMA 薄膜对水蒸气的 QCM 灵敏度比纯 PMMA 薄膜大 3.7 倍。
