Scalable, Low-Energy Processing of Functionally Graded Polymer Composites for Advanced Engineering Applications

Polymer-based functionally graded materials (FGMs) are attractive for soft-rigid interfaces, where filler-rich regions provide local stiffness while matrix-rich regions accommodate deformation, redistribute stress, and dissipate energy. Yet, conventional FGM fabrication is often energy- or equipment-intensive and designed for inorganic systems, limiting compatibility with soft polymers. Here, we report a scalable, low-energy strategy for producing compositional gradients in carbon fibre/PDMS composites. Surface-functionalised, field-responsive carbon fibre reinforcement fillers were incorporated into an uncured PDMS matrix and spatially redistributed to form a monolithic gradient during curing without sequential layering, high-temperature treatment, or complex manufacturing equipment. Successful filler modification and gradient formation were evaluated using morphological, elemental, and spectroscopic analyses, while rheological measurements were used to assess curing behaviour and optimise the processing window for filler redistribution. Mechanical performance was examined to compare uniform and graded composites and evaluate the effect of spatial reinforcement control. Overall, this approach provides a simple platform for tailoring local reinforcement distribution in elastomeric composites, offering potential for adaptive structures, impact-absorbing components, and compliant joints in advanced engineering systems.