Hybrid Poly(urethane鈥搖rea)/Silica Nanocapsules with pH-Sensitive Gateways

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• 作者：Matthew A. Hood ; Umaporn Paiphansiri ; David Schaeffel ; Kaloian Koynov ; Michael Kappl ; Katharina Landfester ; Rafael Mu帽oz-Esp铆
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：June 23, 2015
• 年：2015
• 卷：27
• 期：12
• 页码：4311-4318
• 全文大小：466K
• ISSN：1520-5002

文摘

We have produced hybrid poly(urethane鈥搖rea)/silica nanocapsules with controlled molecular-scale regimes of silica that break upon introduction into basic media. The miniemulsion technique used is simple and scalable but yields complex molecular-scale morphologies that create molecular gates for the release of hydrophilic components. The hybrid nanocapsules displayed no microphase separation, indicating the formation of microscopically mixed regions of silica and poly(urethane鈥搖rea). Using atomic force microscopic techniques, we characterize the mechanical properties of individual capsules and identify the tailorability of the capsule modulus by changing the ratio of isocyanate to silica in the precursor mixture. The compositions of the hybrids were confirmed by infrared spectroscopy and thermogravimetric analysis. The change in size of a nanocapsule with pH and time was monitored by fluorescence correlation spectroscopy to evaluate their potential as nanocontainers and show a pH-responsive release.