Impact-resistant, haze-free, 3D-printable transparent block copolymer resin via photopolymerization-induced microphase separation

Incorporating rubbery domains into glassy polymers is an effective route to improve toughness and impact strength. However, retaining the transparency of the composite material over a wide temperature range with enhanced mechanical attributes is challenging because of a mismatch in refractive indices with changing temperatures, limiting their applications as optical materials. Here, we report photopolymerization-induced microphase separation as a strategy for the fabrication of transparent, temperature-resistant nanostructured polymeric materials. Taking poly(methyl methacrylate) (PMMA) as the glassy component for its renowned high transparency, we perform controlled radical polymerization upon light exposure to transform the whole polymerization mixture into a cross-linked block polymer material, where a bicontinuous nanostructure consisting of PMMA and cross-linked rubbery microdomains spontaneously arises during polymerization in situ. The facile formation of the rubbery domains, smaller than 50 nm yet 3D continuous and cross-linked, is the key to retaining transparency above 120 °C in the visible light wavelength with dimensional stability and allowing efficient stress dissipation through the large interfacial area. We further demonstrate the 3D printability of the nanostructured materials into custom shapes via direct ink writing. Glassy polymers like polystyrene are brittle and not very durable. Researchers have found that adding rubbery polymer domains can make them tougher. However, this often makes the material hazy, which is a problem for optical uses like car windows. Researchers developed a new method using block copolymers to create clear, tough materials without haze. They used a process called polymerization-induced microphase separation (PIMS), which helps keep the rubbery domains small and clear. The researchers mixed different chemicals and used light to start a reaction that created a solid material with tiny, intertwined domains of hard and soft polymers. This new material stayed clear and strong even at high temperatures, unlike traditional materials that become hazy or lose their shape. The team also showed that this material could be used in 3D printing to make complex shapes. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. We developed impact-resistant, haze-free poly(methyl methacrylate) (PMMA) by photopolymerization-induced microphase separation. Upon irradiation, a polymerization mixture transforms into a transparent monolithic solid. A nanoscopic bicontinuous morphology of glassy PMMA with rubbery and cross-linked polymer domains retains transparency and dimension stability even at high temperatures. 3D printing via direct ink writing demonstrates the potential of the developed material for advanced optical and structural applications.