Robust and Highly Stretchable UV‐Curable Rubber/Polyurethane‐Based Resins Reinforced with Photocurable Cellulose Acetate

Abstract Tough and stretchable elastomeric resins are useful materials, particularly for coatings and additive manufacturing, which constructs 3D objects through the successive deposition of curable materials. Though elastomeric resins are valued for their flexibility and mechanical resilience, remain limited in availability. In this work, a photocurable resin capable of producing highly elastic material is designed and synthesized. The resin is derived from polybutadiene‐based thermoset polyurethane, which is degraded and functionalized through olefin cross‐metathesis reaction. The elastomeric resin can be efficiently cured by UV light, affording robust elastomers with an excellent elongation rate (>1300%). The study reveals that the molecular architecture of the resin plays an important role in UV curing and the resulting elastomer properties. Model studies suggest the fragment architecture within the resin prevents shrinkage during UV‐curing, which is a common and undesired phenomenon for photocurable elastomers. Moreover, the elastomeric resin's physical properties are tuned by incorporating a cellulose‐based reinforcing component (CA‐MA) and systematically adjusting the formulation. Tensile testing indicated that the addition of CA‐MA significantly enhanced the modulus and toughness (46 MJ m −3 ) of the UV cured elastomer. Finally, the resin is used as a component in SLA‐based 3D printing transforming the elastomeric resin into complex 3D structures.