Which additive manufacturing material can have a chemical reaction and harden if exposed to light?

Liquid photopolymer is the correct choice because it is a type of additive manufacturing material that hardens through a photochemical reaction upon exposure to light, particularly ultraviolet (UV) light. This process is fundamental to several forms of additive manufacturing, such as stereolithography (SLA) and digital light processing (DLP), where the liquid resin is cured layer by layer to form a solid object. The unique property of liquid photopolymers to change from a liquid state to a solid state makes them particularly useful in applications where detail and resolution are crucial.

In contrast, powdered metal relies on sintering or binding processes and does not undergo any hardening via a light-induced chemical reaction. Thermoplastic filament is a material that becomes pliable or moldable upon heating but does not harden via light exposure. Composite resin is a combination of materials but typically refers to a mixture of polymers and fillers that may enhance certain properties but does not specifically imply a chemical reaction induced by light for hardening.