The influence of post-curing methods on mechanical properties of photosensitive resins using vat photopolymerization for stents

Abstract

Polymeric stents represent a promising alternative to metal-based drug-eluting stents, offering advantages in biocompatibility, reduced vessel trauma, and potential device customization through additive manufacturing technologies. While much research has focused on bioresorbable stents, polymeric permanent stents may offer a safer and more stable long-term solution. However, polymers have inherent limitations compared to metals, including lower mechanical strength and lack of radiopacity. Vat photopolymerization is a promising candidate to manufacture next generation of vascular stents due to its precision and tuneable raw materials. To consolidate the polymeric network of photosensitive materials and to improve mechanical and biological performance of the printed parts, the step of post-curing is essential. In this work, four photosensitive resins were processed by vat photopolymerization and subjected to four post-curing methods (UV, Heat, UV + Heat, and Microwave). Eighty specimens per test type were evaluated through uniaxial tensile and three-point bending tests according to standardized protocols. Specimens were fabricated using vat photopolymerization and tested according to standardized protocols Key properties were evaluated including Young’s modulus, ultimate tensile strength, elongation at break, flexural modulus, and flexural strength. The results demonstrated that resin D80 exhibited the highest stiffness, specially when post-cured with UV and temperature (E, 6.4 ± 1.6 GPa), while D60 showed the greatest ductility (εb, 8.69 ± 2.3 %) with the same conditions. Post-curing methods had a significant influence on mechanical performance: the UV Light + Heat method notably improved tensile strength in D60 and D70 (330–350 %), whereas Microwave curing had a more pronounced effect on flexural properties on D80 (140 %). These findings contribute to the optimization of polymer selection and processing for biomedical devices manufacturing and provide validated data for future computational modelling

This work was financially supported by the Catalan Government through the funding grant ACCIÓ-Eurecat (Project TRAÇA2024-DESTOFU). Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier