Radiation‐Crosslinked PCL – TMPTA Composites via 3D Printing: Structure–Property Relationships and Shape Memory Performance

Programmable materials that can reversibly transform between distinct shapes represent a promising technology for applications spanning biomedicine, robotics, and aerospace engineering. Although shape memory polymers offer promising stimuli‐responsive behavior, current manufacturing approaches limit geometric complexity and performance optimization. Here, we demonstrate a manufacturing strategy that combines radiation‐induced crosslinking with additive manufacturing to create programmable shape memory materials with superior performance and architectural control. This study examines radiation crosslinking of 3D printed polycaprolactone‐trimetylolpropane triacrylate (PCL–TMPTA) composites comprised of two different concentrations of TMPTA (2.5% and 5%), revealing fundamental structure–property relationships that enable rational material design. Specimens were fabricated with optimized 3D printing processing parameters and subsequently crosslinked using 60 Co gamma irradiation (5–25 kGy). An unprecedented enhancement in extensional stress from 10 kPa (unirradiated) to 120 kPa (25 kGy) for PCL–TMPTA composites—a 12‐fold improvement—highlights the modification using high energy radiation. Additionally, the delay in relaxation time in stress relaxation reflects the additional macromolecular linkage that critically ensures shape fixity and shape memory behavior. Shape memory evaluation through thermo‐mechanical cycling at 70°C achieved perfect shape fixity ratios of 100% and recovery ratios exceeding 98% for crosslinked specimens, representing state‐of‐the‐art performance. Microstructural analysis via polarized light microscopy and micro‐computed tomography confirmed radiation‐induced morphological evolution and structural integrity preservation during shape memory cycles.