Facile fabrication of shape memory poly(ε-caprolactone) non-woven mat by combining electrospinning and sol–gel reaction

Abstract

A smart combination of electrospinning and sol–gel reaction enabled to develop crosslinked poly(ε-caprolactone) fibrous mats showing excellent shape memory properties.

Mutifunctional Electrospun Nonwoven Mats with Two‐Way Shape Memory Behavior Prepared from Sol–Gel Crosslinked Poly(ε‐Caprolactone)

“…The increase of the inflection temperature with the applied stress is a well‐known effect in bulk systems, and it is ascribed to the easier crystallization taking place under highly stretched state, whereas the broadening of the transition may be interpreted as a consequence of the evolution of the fiber morphology. In fact, as already observed for the present system, for strains up to 100% the fibers tend to deform through a simultaneous occurrence of rotational and flexural rearrangements, by which the fibers appear as uniformly deformed; only at higher strains, a proper stretching of the fibers takes place, leading to a less homogeneous structure, where highly stretched fibers, and buckled transverse fibers (i.e., those laying perpendicularly to the load direction) can be found. This may be at the basis of the sharp elongation occurring at low strain, where all the homogeneously deformed fibers contribute to the material elongation; on the other hand, the more distributed elongation may be due to different contributions provided by the variously stretched fibers.…”

“…Therefore, such difficulties in setting precise values of stress and strain from specimen to specimen prohibited a proper evaluation of the experimental errors by means of repeated experiments. However, previous experience on the one‐ and two‐way shape memory tests on various materials and further side‐experiments on the PCL nonwovens allowed us to estimate that the relative error may be considered to be about 1%, and in any case less than 10%. The values presented in Tables and were reasonably rounded to an according number of significant digits.…”

“…In companion papers more details can be found concerning the preparation of α,ω‐triethoxysilane‐terminated PCL and its sol–gel crosslinking, the electrospinning apparatus, and the processing conditions …”

“…An extensive characterization of the obtained mats is presented in a companion paper, and the main results are summarized here.…”

“…In a recent article, a facile route to realize electrospun systems out of semicrystalline networks was proposed for PCL‐based materials. The creation of a crosslinked structure was achieved with a process based on the sol–gel chemistry and the obtained films revealed an ideal one‐way shape memory response, with high fixation and recovery capabilities, and the possibility to undergo reversible structuring of the fibrous networks from a highly aligned to a randomly oriented configuration . In this work, the knowledge on material properties is further deepened by exploring their performance under the perspective of a multifunctional response, and in particular in evaluating their ability to: (i) undergo one‐way shape memory response in nonconventional histories (i.e., cold‐working), (ii) exhibit the two‐way shape memory behavior, and (iii) sustain cell adhesion and proliferation.…”