Direct Integration of Electrospun Polycaprolactone Fibers with Polydimethylsiloxane: Influence of Elastomer Formulation on Fiber–Elastomer Adhesion

The increasing use of complex medical devices has intensified the need for reliable integration of multiple biocompatible materials. Silicone elastomers are widely used in implantable devices and frequently combined with materials designed to support cell growth. In such hybrid systems, robust interfacial adhesion is essential for mechanical stability and functional performance. In this study, electrospun poly(ε-caprolactone) (PCL) fibers were deposited directly onto two silicone elastomers, RTV 4420 and Sylgard 184, to form mechanically integrated bilayer structures. Adhesion of the electrospun PCL membrane to the silicone substrates was evaluated using a 180° peel test, while fiber morphology and surface topography were characterized to investigate the influence of the substrate material. The mean steady-state adhesive strength measured for the electrospun PCL membrane and RTV 4420 was 4.76 ± 0.05 mN/mm (mean ± SEM), compared with 6.83 ± 1.49 mN/mm for Sylgard 184. Distinct differences in residual bead formation and fiber morphology were observed between fibers collected on polydimethylsiloxane (PDMS) and aluminum foil. Fiber diameter differed significantly when spun onto uncured Sylgard 184 compared with uncured RTV 4420 or aluminum foil. Additionally, high-voltage electrospinning induced transient surface structures in the uncured silicone that were retained in the fiber pattern after voltage removal. Overall, direct electrospinning enabled PCL–silicone adhesion while providing control over fiber morphology, offering a promising approach for developing stable, cell-supporting interfaces in research and medical devices.