Thermomechanical Tailoring of a DLP-Printable Shape Memory Polyurethane for Vascular Graft Applications

Abstract

The increasing prevalence of cardiovascular diseases highlights the need to develop vascu-lar grafts that match the mechanics of native vascular tissue and offer functional adaptabil-ity. This study reports the development and systematic optimization of a shape-memorypolyurethane acrylate (PUA)-based photocurable resin for digital light processing (DLP)-based four-dimensional printing (4DP) applications. Resin formulations were designed bycontrolling hard/soft segment ratios, reactive diluent content, and crosslink density to po-sition the glass transition temperature (T-g) within the physiological range(25-40 degrees C).Ther-momechanical characterization was performed via dynamic mechanical analysis (DMA)and tensile testing, while a full-factorial Design of Experiments (DoE) approach was appliedto optimize DLP process parameters-namely layer thickness, exposure time, and post-curing time. The developed resin formulation yielded a T-g of 38 degrees C as determined by DMA.Following process optimization, regression models showed high statistical fit(R2> 99%),and experimental validation under optimal conditions (layer thickness:82.83 mu m,expo-sure time: 11 s, post-curing: 2 min) resulted in an elongation at break of 64.0 +/- 3.4%, aYoung's modulus of 10.9 +/- 0.1 MPa, and a tensile strength of 6.2 +/- 0.3 MPa. The optimizedsystem exhibited thermally triggerable shape memory behavior at near-body tempera-ture, with mechanical properties consistent with natural arterial tissue benchmarks. Thesefindings demonstrate a promising material design strategy for DLP-based 4D-printedvascular structures.