Programming shape and tailoring transport: advancing hygromorphic bilayers with aligned nanofibersElectronic supplementary information (ESI) available: Electrospinning set-up and calculated diffusion coefficients; videos of natural curvature of bilayer composites with vertically-aligned, horizontally-aligned, and diagonally-aligned nanofibers. See DOI: 10.1039/c7sm00962c

• Main Authors: Alexander, S. L. M, Ahmadmehrabi, S, Korley, L. T. J
• Format: Journal Article
• Language: English
• Published: 23.08.2017
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/c7sm00962c

Natural systems utilize nanofiber architectures to guide water transport, tune mechanical properties, and actuate in response to their environment. In order to harness these properties, a hygromorphic bilayer composite comprised of a self-assembled fiber network and an aligned electrospun fiber network was fabricated. Molecular gel self-assembly was utilized to increase hydrophobicity and strength in one layer, while aligned electrospun poly(vinyl alcohol) (PVA) nanofibers increased the rate of hydration and facilitated tunable actuation in the other. Interfacing these two fiber networks in a poly(ethylene oxide- co -epichlorohydrin) (EO-EPI) matrix led to hydration-driven actuation with tunable curvature. Specifically, variations in fiber alignment were achieved by cutting at 0, 90, and 45 degree angles in relation to the length edge of the composite. Along with the ability to program the natural curvature, the utilization of aligned nanofibers increased water transport compared to random nanofiber systems, resulting in a reduction in response time from 20+ minutes to 2-3 minutes. Nanofiber alignment was utilized as a manufacturing strategy for hygromorphic bilayers to control response rate and shape through transport anisotropy.