(77b) Stimuli-Responsive Composites Containing Aligned Nanofibers

A variety of natural systems ranging from extracellular matrices to cellulose nanofibers utilize aligned nanofibers to achieve unique functions (e.g., cell growth and regeneration, fluid and cellular transport, and improved mechanical properties). Inspired by these natural systems, composite materials comprised of aligned, electrospun nanofibers have gained signification attention due to their utility in variety of applications including drug delivery, cellular transportation, sensing, and flexible electronics. Electrospinning is a widely recognized and popular technique for the production of aligned fibers due to the advantages it offers such as precise control over fiber alignment, scalability for large-scale production, compatibility with a variety of materials, and versatility in fiber morphology manipulation. While numerous studies have successfully fabricated aligned nanofibers using electrospinning and their composite counterparts, attaining consistently highly aligned and mechanically robust nanofibers with a diverse range of responsive and chemical functionalities remains a significant hurdle in the field.

In our study, we employed electrospinning to fabricate aligned nanofibers with targeted structural and functional properties. Firstly, we engineered aligned, stimuli-responsive poly(vinyl alcohol) (PVA) fibers containing clay nanoparticles, achieving an array of mechanical properties and varying fiber sizes through the electrospinning process. Secondly, polyacrylic acid (pAA) was electrospun to obtain nanofibers responsive towards ions, hydration, and electrical stimuli. Both the clay-containing PVA nanofibers and functional pAA nanofibers were separately embedded within a soft, ethylene oxide-co-epichlorohydrin (EO-EPI) matrix to form responsive, single layer electrospun composites. We also fabricated bilayer composites comprised of a rigid, passive layer of a low-molecular-weight gel in EO-EPI and the active pAA or PVA nanofibers embedded in EO-EPI, inducing controlled, fast actuation in response to various stimuli. These single-layer and bilayer composites offer a facile approach to regulate water and small molecule transport relevant to agriculture and drug delivery applications. In summary, the utilization of nanofillers and inherent chemical functionality in an aligned, engineering nanofiber platform led to multifunctional and versatile material responses.

References:

1. Alexander, S. L. M., & Korley, L. T. J. (2017). Tunable hygromorphism: structural implications of low molecular weight gels and electrospun nanofibers in bilayer composites. Soft Matter, 13(1), 283-291.
2. Alexander, S. L. M., Ahmadmehrabi, S., & Korley, L. T. J. (2017). Programming shape and tailoring transport: advancing hygromorphic bilayers with aligned nanofibers. Soft Matter, 13(33), 5589-5596.
3. Wanasekara, N. D., Matolyak, L. E., & Korley, L. T. J. (2015). Tunable mechanics in electrospun composites via hierarchical organization. ACS Applied Materials & Interfaces, 7(41), 22970-22979.