Search

Mesoporous titania microspheres (MTMs) have been employed in many applications, including (photo)catalysis as well as energy conversion and storage. Their morphology offers a hierarchical structural design motif that lends itself to being incorporated into established large-scale fabrication processes. Despite the fact that device performance hinges on the precise morphological characteristics of these materials, control over the detailed mesopore structure and the tunability of the pore size remains a challenge. Especially the accessibility of a wide range of mesopore sizes by the same synthesis method is desirable, as this would allow for a comparative study of the relationship between structural features and performance. Here, we report a method that combines sol–gel chemistry with polymer micro- and macrophase separation to synthesize porous titania spheres with diameters in the micrometer range. The as-prepared MTMs exhibit well-defined, accessible porosities with mesopore sizes adjustable by the choice of the polymers. When applied as an anode material in lithium ion batteries (LIBs), the MTMs demonstrate excellent performance. The influence of the pore size and an in situ carbon coating on charge transport and storage is examined, providing important insights for the optimization of structured titania anodes in LIBs. Our synthesis strategy presents a facile one-pot approach that can be applied to different structure-directing agents and inorganic materials, thus further extending its scope of application.

Mesoporous titania microspheres (MTMs) have been employed in many applications, including (photo)catalysis as well as energy conversion and storage. Their morphology offers a hierarchical structural design motif that lends itself to being incorporated into established large-scale fabrication processes. Despite the fact that device performance hinges on the precise morphological characteristics of these materials, control over the detailed mesopore structure and the tunability of the pore size remains a challenge. Especially the accessibility of a wide range of mesopore sizes by the same synthesis method is desirable, as this would allow for a comparative study of the relationship between structural features and performance. Here, we report a method that combines sol–gel chemistry with polymer micro- and macrophase separation to synthesize porous titania spheres with diameters in the micrometer range. The as-prepared MTMs exhibit well-defined, accessible porosities with mesopore sizes adjustable by the choice of the polymers. When applied as an anode material in lithium ion batteries (LIBs), the MTMs demonstrate excellent performance. The influence of the pore size and an in situ carbon coating on charge transport and storage is examined, providing important insights for the optimization of structured titania anodes in LIBs. Our synthesis strategy presents a facile one-pot approach that can be applied to different structure-directing agents and inorganic materials, thus further extending its scope of application.

We report a facile and versatile strategy for the bespoke fabrication of macro- and mesoporous block copolymer microparticles. A clean synthetic route, RAFT dispersion polymerisation in supercritical carbon dioxide (scCO2), is used to generate block copolymer microparticles. Selective swelling/deswelling is then applied to induce controlled morphology transitions and to trap the resulting porous state. The pore sizes are controllable over a large size range (~20 – 200 nm) by varying the length of the swellable block. Through a systematic approach we then demonstrate that the shape of the pores can also be tailored from isolated spheres through to interconnected/bicontinuous channels by varying the ratio of the two blocks. This process is shown to be applicable to a range of poly(methyl methacrylate) (PMMA)based block copolymer systems, including PMMA-b-poly(4-vinyl pyridine), PMMAb-poly(dimethyl acrylamide) (DMA) and PMMA-bpoly(dimethylaminoethylmethacrylate) (DMAEMA). In each case, the second minority block (e.g. P4VP, etc.) was selectively swollen with an alcohol to induce an order-toorder morphology transition and then quenched rapidly by the non-solvent hexane. This not only takes place on the order of hours, but is also freely scalable for the production of grams of material and beyond in a single step following polymerisation.

We report a facile and versatile strategy for the bespoke fabrication of macro- and mesoporous block copolymer microparticles. A clean synthetic route, RAFT dispersion polymerisation in supercritical carbon dioxide (scCO2), is used to generate block copolymer microparticles. Selective swelling/deswelling is then applied to induce controlled morphology transitions and to trap the resulting porous state. The pore sizes are controllable over a large size range (~20 – 200 nm) by varying the length of the swellable block. Through a systematic approach we then demonstrate that the shape of the pores can also be tailored from isolated spheres through to interconnected/bicontinuous channels by varying the ratio of the two blocks. This process is shown to be applicable to a range of poly(methyl methacrylate) (PMMA)based block copolymer systems, including PMMA-b-poly(4-vinyl pyridine), PMMAb-poly(dimethyl acrylamide) (DMA) and PMMA-bpoly(dimethylaminoethylmethacrylate) (DMAEMA). In each case, the second minority block (e.g. P4VP, etc.) was selectively swollen with an alcohol to induce an order-toorder morphology transition and then quenched rapidly by the non-solvent hexane. This not only takes place on the order of hours, but is also freely scalable for the production of grams of material and beyond in a single step following polymerisation.

We report a facile and versatile strategy for the bespoke fabrication of macro- and mesoporous block copolymer microparticles. A clean synthetic route, RAFT dispersion polymerisation in supercritical carbon dioxide (scCO2), is used to generate block copolymer microparticles. Selective swelling/deswelling is then applied to induce controlled morphology transitions and to trap the resulting porous state. The pore sizes are controllable over a large size range (~20 – 200 nm) by varying the length of the swellable block. Through a systematic approach we then demonstrate that the shape of the pores can also be tailored from isolated spheres through to interconnected/bicontinuous channels by varying the ratio of the two blocks. This process is shown to be applicable to a range of poly(methyl methacrylate) (PMMA)based block copolymer systems, including PMMA-b-poly(4-vinyl pyridine), PMMAb-poly(dimethyl acrylamide) (DMA) and PMMA-bpoly(dimethylaminoethylmethacrylate) (DMAEMA). In each case, the second minority block (e.g. P4VP, etc.) was selectively swollen with an alcohol to induce an order-toorder morphology transition and then quenched rapidly by the non-solvent hexane. This not only takes place on the order of hours, but is also freely scalable for the production of grams of material and beyond in a single step following polymerisation.

We report a facile and versatile strategy for the bespoke fabrication of macro- and mesoporous block copolymer microparticles. A clean synthetic route, RAFT dispersion polymerisation in supercritical carbon dioxide (scCO2), is used to generate block copolymer microparticles. Selective swelling/deswelling is then applied to induce controlled morphology transitions and to trap the resulting porous state. The pore sizes are controllable over a large size range (~20 – 200 nm) by varying the length of the swellable block. Through a systematic approach we then demonstrate that the shape of the pores can also be tailored from isolated spheres through to interconnected/bicontinuous channels by varying the ratio of the two blocks. This process is shown to be applicable to a range of poly(methyl methacrylate) (PMMA)based block copolymer systems, including PMMA-b-poly(4-vinyl pyridine), PMMAb-poly(dimethyl acrylamide) (DMA) and PMMA-bpoly(dimethylaminoethylmethacrylate) (DMAEMA). In each case, the second minority block (e.g. P4VP, etc.) was selectively swollen with an alcohol to induce an order-toorder morphology transition and then quenched rapidly by the non-solvent hexane. This not only takes place on the order of hours, but is also freely scalable for the production of grams of material and beyond in a single step following polymerisation.