Functional and Smart Materials by Electrospinning for Advanced Applications

摘要

The processing of advanced and functional polymers with electrospinning brings enormous potentialities to either improve or extend their properties. A representative example is the field of mechanochromic materials, potentially exploitable for imaging mechanical damages and stress/strain distribution. An effective stress-sensing material must respond to low deformation with a detectable color change that should be quickly reversible upon force unloading. In the present study we processed a spiropyran main chain polymer by electrospinning and fibers with a proper weaving were included in a PDMS elastomeric matrix to produce composite materials. Measurements of fiber birefringence demonstrated that, after electrospinning, polymer chains were successfully vitrified in a highly oriented conformation. Stress strain tests, coupled with a real-time detection of color, showed that fibers displayed a clear color change after only 5% of deformation. When these highly sensitive mechanochromic nanofibers were incorporated in a PDMS matrix, either anisotropic or isotropic mechanochromic behavior was achieved, depending on fiber alignment. The unique mechanochromic properties of the proposed composites, i.e. reversibility, sensitivity and directionality, derive by a smart combination of chemical synthesis, processing and composite design, respectively, and make them ideal to act as real-time stress/strain-sensing materials.