Programmable Light-Controlled Shape Changes in Layered Polymer Nanocomposites

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• 作者：Zhichen Zhu ; Erkan Senses ; Pinar Akcora ; Svetlana A. Sukhishvili
• 刊名：ACS Nano
• 出版年：2012
• 出版时间：April 24, 2012
• 年：2012
• 卷：6
• 期：4
• 页码：3152-3162
• 全文大小：665K
• 年卷期：v.6,no.4(April 24, 2012)
• ISSN：1936-086X

文摘

We present soft, layered nanocomposites that exhibit controlled swelling anisotropy and spatially specific shape reconfigurations in response to light irradiation. The use of gold nanoparticles grafted with a temperature-responsive polymer (poly(N-isopropylacrylamide), PNIPAM) with layer-by-layer (LbL) assembly allowed placement of plasmonic structures within specific regions in the film, while exposure to light caused localized material deswelling by a photothermal mechanism. By layering PNIPAM-grafted gold nanoparticles in between nonresponsive polymer stacks, we have achieved zero Poisson鈥檚 ratio materials that exhibit reversible, light-induced unidirectional shape changes. In addition, we report rheological properties of these LbL assemblies in their equilibrium swollen states. Moreover, incorporation of dissimilar plasmonic nanostructures (solid gold nanoparticles and nanoshells) within different material strata enabled controlled shrinkage of specific regions of hydrogels at specific excitation wavelengths. The approach is applicable to a wide range of metal nanoparticles and temperature-responsive polymers and affords many advanced build-in options useful in optically manipulated functional devices, including precise control of plasmonic layer thickness, tunability of shape variations to the excitation wavelength, and programmable spatial control of optical response.

Keywords:

nanocomposites; light-responsive materials; soft actuators; shape-changing materials; zero Poisson鈥檚 ratio; metal nanoparticles; photothermal effect; poly(N-isopropylacrylamide); rheology