Regulating copolymer architecture using photoiniferter polymerization to direct composite morphology

From Unregulated Networks to Designed Microstructures: Introducing Heterogeneity at Different Length Scales in Photopolymers for Additive Manufacturing

“…In another patent block copolymers have been claimed in combination with ring opening monomers, leading again to significantly tougher materials . A similar concept was realized with the previously introduced photoiniferters for radical/cationic hybrid systems, which give block copolymers with improved mechanical properties …”

“…Furthermore, photo-iniferters have been explored in the field of radical/cationic hybrid systems, giving block copolymers with improved mechanical properties. 98 While CTA-regulated networks generally report improved mechanical behavior in terms of toughness (at room temperature), this is often accompanied by a drop in their glass transition temperature due to the reduced cross-linking density.…”

“…283 A similar concept was realized with the previously introduced photoiniferters for radical/cationic hybrid systems, which give block copolymers with improved mechanical properties. 98 Most recently, photopolymer networks have been investigated where the block copolymer polyethylene-block-poly-(ethylene oxide) was incorporated into a methacrylate matrix without covalent attachment to the network to investigate the material's crystallization behavior and effects on the mechanical response (Figure 25b). 269 The matrix did not disturb the establishment of nanoribbons with a semicrystalline polyethylene core during heating−cooling cycles but confined the size of crystalline domains.…”

“…In other examples, macroRAFT reagents have been utilized for similar purposes. − The mechanical properties can be modified within a broad range, the printing resolution was reported to be increased compared to free radical vat photopolymerization of comparable rates, and phase separation can be achieved through a clever choice of reagents. Furthermore, photo-iniferters have been explored in the field of radical/cationic hybrid systems, giving block copolymers with improved mechanical properties . While CTA-regulated networks generally report improved mechanical behavior in terms of toughness (at room temperature), this is often accompanied by a drop in their glass transition temperature due to the reduced cross-linking density.…”

Effect of Block Copolymer Self-Assembly on Phase Separation in Photopolymerizable Epoxy Blends

“…Photoiniferter polymerization is a controlled radical polymerization (CRP) technique that offers exceptional control over functional group placement, molecular weight, dispersity, and block volume fraction. , The photoiniferter process typically employs trithiocarbonate species as a photoinitiator, chain transfer, and a reversible termination agent to facilitate controlled polymerization. Since there is no need for an exogenous initiator, concentration of irreversibly terminated chains is considerably reduced, permitting facile block addition with subsequent monomer feeds. , Additionally, the polymerization can be conducted at room temperature in a closed system which reduces iniferter degradation and monomer evaporation, thereby allowing molecular weight to be targeted more accurately relative to thermally initiated CRP systems, as shown in our recent work . Ultimately, this process enables precise control over polymer architecture, which may facilitate targeted interactions within a photocurable matrix.…”