Tailoring of Interfacial Mechanical Shear Strength by Surface Chemical Modification of Silicon Microwires Embedded in Nafion Membranes
Abstract
The interfacial shear strength between Si microwires and a Nafion membrane has been tailored through surface functionalization of the Si. Acidic (−COOH-terminated) or basic (−NH_2-terminated) surface-bound functionality was introduced by hydrosilylation reactions to probe the interactions between the functionalized Si microwires and hydrophilic ionically charged sites in the Nafion polymeric side chains. Surfaces functionalized with SiO_x, Si–H, or Si–CH_3 were also synthesized and investigated. The interfacial shear strength between the functionalized Si microwire surfaces and the Nafion matrix was quantified by uniaxial wire pull-out experiments in an in situ nanomechanical instrument that allowed simultaneous collection of mechanical data and visualization of the deformation process. In this process, an axial load was applied to the custom-shaped top portions of individual wires until debonding occurred from the Nafion matrix. The shear strength obtained from the nanomechanical measurements correlated with the chemical bond strength and the functionalization density of the molecular layer, with values ranging from 7 MPa for Si–CH3 surfaces to ∼16–20 MPa for oxygen-containing surface functionalities. Hence surface chemical control can be used to influence the mechanical adhesion forces at a Si–Nafion interface.
Additional Information
© 2015 American Chemical Society. Received for review January 21, 2015 and accepted April 14, 2015. Publication Date (Web): April 14, 2015. This research made use of the Shared Experimental Facilities supported by the Molecular Materials Research Center at the California Institute of Technology and of funds provided by the National Science Foundation (NSF) Center for Chemical Innovation: Solar Fuels (Grant CHE-1305124). B.M.G. acknowledges financial support from a Caltech Kavli Nanoscience Institute Prize Postdoctoral Fellowship.Attached Files
Supplemental Material - nn5b00468_si_001.pdf
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Additional details
- Eprint ID
- 57086
- DOI
- 10.1021/acsnano.5b00468
- Resolver ID
- CaltechAUTHORS:20150429-103132238
- NSF
- CHE-1305124
- Kavli Nanoscience Institute
- Created
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2015-04-29Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Kavli Nanoscience Institute