Composition‐Dependent Mechanical, Thermal, and Surface Properties of Stereolithography‐Printed TPU / PMMA Photopolymer Blends

ABSTRACT Photocurable thermoplastic polyurethane (TPU)/poly(methyl methacrylate) (PMMA) blends were formulated for stereolithography (SLA) to examine how blend composition affects intermolecular interactions, phase morphology, thermal behavior, mechanical response, and surface wettability of photocured networks. TPU‐based photocurable resin, PMMA‐based photocurable resin, and four intermediate blends (TPU: PMMA = 9:1, 7:3, 1:1, and 3:7, w/w) were printed under a single optimized, fully dense (100% infill) parameter set. FTIR spectroscopy confirmed that all compositions remained physically blended, with carbonyl‐ and amide‐band positions consistent with composition‐dependent urethane–carbonyl hydrogen bonding. FE‐SEM surface‐morphology imaging of the as‐printed surfaces showed a shift from fibrous, textured features in TPU‐rich compositions to denser, smoother features as PMMA content increased. Differential scanning calorimetry of the two most contrasting compositions (7:3 and 1:1) showed a sharp sub‐ambient thermal event, tentatively attributed to a melting‐type transition of ordered TPU soft‐segment domains rather than a glass transition, shifting from −14°C (7:3) to −11°C (1:1) with increasing PMMA content; this assignment remains provisional given the proximity to the lower instrumental limit and the two‐composition dataset. Thermogravimetric analysis across all six compositions showed that thermal stability generally increased with PMMA content, with the 3:7 blend showing the highest onset decomposition temperature and char yield. Static contact angle and swelling measurements identified the 7:3 composition as the most hydrophilic (37.4°) and most swollen (2.37% at 18 h) in the series. Tensile testing showed PMMA‐based photocurable resin to be the strongest and stiffest composition (30.5 MPa, 17.2 MPa modulus) and TPU‐based photocurable resin the most extensible (96.5% elongation), while the 3:7 blend offered the best overall strength–stiffness–ductility balance among the blended compositions (14.2 MPa, 12.2 MPa modulus, 70.3% elongation); the 7:3 and 1:1 compositions are lower‐modulus, elastomer‐dominated formulations rather than high‐performance structural materials. Collectively, these results provide composition‐dependent structural observations for photocurable TPU/PMMA blends and illustrate compositional control as an accessible route for tuning the mechanical, thermal, and surface behavior of SLA‐printed polymer networks.